1Key Laboratory of Efficient Irrigation-Drainage and Agricultural Soil-Water Environment in Southern ChinaMinistry of Education College of Water Conservancy and Hydropower Engineering Hohai University Nanjing 210098 China2Jiangsu Water Conservancy Research Institute Nanjing Jiangsu 210017 China3Jiangsu Coastal Water Conservancy Research Institute Dongtai Jiangsu 224200 China4Water Conservancy Survey and Design Institute Co Ltd Huairsquoan 223005 China
Correspondence should be addressed to Shao-feng Yan shaofey163com and Shuang-en Yu seyuhhueducn
Received 3 August 2014 Revised 6 September 2014 Accepted 8 September 2014
Academic Editor Jun Wu
Copyright copy 2015 Shao-feng Yan et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited
The coastline of China is approximately 18000 km long In most coastal cities seawater intrusion is a serious threat to groundwaterresources Nine shallow monitoring wells were constructed to study the dynamics of shallow groundwater level and salinity inthe coastal plain region of Jiangsu province China Results showed that precipitation evaporation and river stage affected thegroundwater level in our study area Positive correlations were observed among the groundwater level precipitation and river stagethen negative correlation existed between the groundwater level and evaporationThe influencing factors on the groundwater levelwere in the order precipitation gt river stage gt evaporation Sufficient precipitation during the wet season diluted the groundwatersalinity After the dilution between two continuous precipitation events the groundwater salinity increased as the groundwater leveldecreased During the dry season the groundwater salinity rapidly increased and reached its peak in December The groundwatersalinity in December was 23 times higher than that in JulyThe groundwater level and salinity in this study were generally associatedwith the season Climate factors led to fluctuation of groundwater levels and salinity during the wet season and seawater intrusionincreased the groundwater salinity during the dry season
1 Introduction
Knowledge of hydrological processes (change of groundwaterlevel groundwater quality and tidal level) in coastal aquifersis important because approximately 50 percent of the worldpopulation live in coastal zones particularly in low-lyingdeltaic areas within 60 km of the shoreline [1] Coastalaquifers typically serve as a major source of freshwater suchas drinking or irrigation water [2]
The groundwater level is a key parameter for evaluatingspatial and temporal changes in groundwater environments[3] The groundwater level is governed by various factorsClimate change as reflected in precipitation and evapo-ration rates influences the groundwater level fluctuation[4] Chen et al also found that climate trends have high
correlations with groundwater level variations in southernManitoba [5] In plain areas precipitation infiltration andevapotranspiration in the vertical direction are the majorrecharge and discharge processes of the water cycle [6]In our study area most of rainfall falls between July andOctober Seasonal variation in climate is very obvious Sowe focus on the influence of short-term seasonal variationin climate on groundwater level in this place The impact ofclimate variability on groundwater levels can be investigatedby analyzing the relationship between climate records andgroundwater level fluctuations
The groundwater salinity is an important groundwaterquality indicator which is controlled by the factors suchas precipitation evapotranspiration mineralogy type ofaquifers topography and seawater intrusion [7] Climate
Hindawi Publishing CorporationJournal of ChemistryVolume 2015 Article ID 905190 8 pageshttpdxdoiorg1011552015905190
2 Journal of Chemistry
change and sea level rise exacerbated saltwater intrusionthereby jeopardizing water use safety especially during thedry season [8] Saltwater intrusion can degrade water qualityand reduce available water if insufficient freshwater are enter-ing the groundwater system and it becamemore serious thanit was before particularly in delta areas because of climatechange [8] Saltwater intrusion occurred globally in morethan 50 countries and regions particularly North Africathe Middle East the Mediterranean China Mexico andthe Atlantic and Gulf Coasts of the United States includingSouthernCalifornia [9 10] Saltwater intrusion can negativelyaffect coastal ecosystems in terms of freshwater quality andthe dynamics of plant community Along with saltwaterintrusion salinization of the groundwater systems may affectagriculture and domestic and industrial water supplies [11]Extensive researches were conducted worldwide to under-stand the mechanisms of saltwater intrusion Environmentalconditions such as precipitation and evapotranspiration wereclustered with hydraulic heads to show that they also influ-ence salinity concentration in groundwater [7] In someplaceseawater intrusion affects groundwater salinity in particularseason For example Rabbani et al confirmed that salinewater starts to penetrate inland during winter months [12] Itis necessary to know the seasonal variations in groundwatersalinity
Groundwater plays a crucial role in the socioeconomicdevelopment of Jiangsu coastal plain a developed area ineastern China In this place shallow groundwater is easilyaffected by environment such as climate change river stageandYellow Sea tidal levelWith a growing population Jiangsufaces an increasing demand for freshwater For solving thisproblem deeply understanding the groundwater system andits influencing factors is necessary Then the relationshipsamong the groundwater level and climate factors river stageYellow Sea tide level and variations in groundwater salinityin this area have not been studied
Thus the purpose of this present study was to investigatethe seasonal variations of groundwater level and salinity inJiangsu coastal plain Specific objectives were (1) to detectthe dynamics of groundwater level and salinity in wet anddry season (2) to determine the relationships among thegroundwater level salinity content climate factors (precipi-tation and evaporation) river stage and Yellow Sea tide levelThis study can provide a management method for coastalplain groundwater by analyzing the factors that influence thegroundwater level and the changing trends of groundwatersalinity
2 Materials and Methods
21 Study Site Description Observational data on thegroundwater level and salinity in Dongtai (120∘071015840sim120∘531015840 Eand 32∘331015840sim32∘571015840 N) Jiangsu in eastern China were collectedand investigated (Figure 1) Jiangsu coastal plain lies to thewest of the Yellow Sea at an altitude ranging from 26m to46m above sea level Dongtai city is in the east of Jiangsuprovince and adjacent to the Yellow Sea The plain sandyarea has a highly permeable soil that consists of mealy sand
and extremely fine sand particles The phreatic surface isat a shallow depth generally 1m to 3m and even 02mafter rainfall below the ground surface The average annualtemperature average annual rainfall and evaporation rateare approximately 150∘C 10598mm and 10067mm respec-tively During the study period in 2013 the annual meanprecipitation was approximately 859mm The maximumprecipitation is recorded in July before gradually decreasingThe annual evaporation is approximately 6515mm Over50 of the rainfall falls between July and October Mostrainfall in the summer is in the form of local showers andthunderstorms and in winter the rainfall amount is small
Considering that most rainfall falls between July andOctober and very small amount of rainfall falls betweenNovember and December in this place July to October isrecognized as the wet season and November to December isthe dry season
22 Experiment Design A farmland covering an area of 50mtimes 100m was selected as a typical saline groundwater site witha shallow water table to study the water and salt dynamicsduring different seasons The farmland was bulldozed bymachine to make sure the land is flat and there is novegetation in the farmland The farmland is approximately5 km away from the Yellow Sea and 2 km away fromLiangduoRiver Nine shallow monitoring wells were constructed andinstalled to a depth of 5m in the aquifer of the farmland(Figure 2)
Data on daily precipitation evaporation river stage andthe Yellow Sea tide level were gathered from the LiangduoRiver dam monitoring point of Jiangsu Province Hydrologyand Water Resources Investigation Bureau which is locatedaround 15 km northeast of the farmland Precipitation datawere collected using a rain gauge and evaporation wasmeasured using an E601 evaporation pan Mean daily riverstage and survey of tide data were recorded manually andautomatically using a groundwater levelmonitoring system atLiangduo River dam The recorded groundwater levels werebased on the 1985Yellow Sea elevation All datawere collectedfrom July 1 2013 to December 31 2013
Manualmonitoring logger was set to observe the ground-water table and groundwater samples collected daily fromthe nine wells spread in the area The recorded water levelsare below the 1985 height of the Yellow Sea Each sampleof 100mL was collected from the upper monitor well Dailygroundwater level and salinity from all wells were monitoredmanually and analyzed The groundwater level of nine wellshad the same trendThe average value of the daily groundwa-ter level and salinity of nine wells were obtained from July 12013 to December 31 2013 The salinity value was calibratedunder 25∘C
3 Results
31 Variations in Groundwater Level The average depthof groundwater in the study area was 17m In the dailygroundwater fluctuation figure the shallowest groundwaterlevel and the deepest groundwater level were identified The
Journal of Chemistry 3
JiangsuHuang He
China
Mongolia
Japan
KoreaRepublic of Korea
Yellow SeaEast China Sea
South China Sea
(km)
BoundaryRiver
SeaJiangsu province
N
0 1000 2000500
Yang
tze
(a)
Dongtai
The farmlandLiangduo River management
Liangduo River
Jiangsu
Dongtai
N
Yellow Sea
5km
0 5 10 20
(km)
BoundaryRiver
SeaJiangsu province
(b)
Figure 1 Geographical location of the study area (a) Jiangsu province in China (b) Dongtai city of Jiangsu province and the farmland
Observational well
The farmland
0 5 10 20
(m)
N
Figure 2 Distribution of the observation wells
first situation corresponded to one of the shallowest waterlevels (on October 8) and the other to the deepest one onAugust 24 (Figure 3)The shallowest and deepest water levelswere 24 cm and 254 cm respectively
The main factors that affected groundwater interac-tion were the climate parameters (rainfall and evaporationdemand) [13] Precipitation infiltration was a key rechargesource of shallow groundwater as well as the major rechargesource of groundwater [14] We observed that the groundwa-ter level exhibited multipeak and multivalley curves and thefluctuation cycle of groundwater synchronized with precip-itation events (Figure 3(a)) During the wet season frequentand sufficient rainfall led to large fluctuations in groundwaterlevel and the shallowest water level was reached As indicatedin Figure 3(a) the fluctuation range related to rainfall peakedat 188 cm after heavy rain with 744 cm precipitation onAugust 24 and a day of precipitation infiltration During
the dry season the groundwater level fluctuated within anarrow range with low precipitation During a nonrainfallperiod the groundwater level exhibited a linear downwardtrend because of evaporation and then increased until thenext precipitation occurred (Figures 3(a) and 3(b)) Theperiod from August 1 to 19 is characterized by absence ofrainfall together with elevated temperatures and potentialevapotranspiration the longest nonrainfall period during thewet season occurred During this period the groundwaterlevel reduced by 175 cmThegroundwater level increased afterthe precipitation events and then decreased gradually withevaporationThe groundwater tables variedwithin the periodfrom wet to dry seasons and showed seasonal variationsbecause of the seasonal distribution of precipitation andevaporation
In the condition of wake evaporation in Decemberdownward trend of groundwater level was not obvious andeven the level on December 31 was 3 cm shallower thanDecember 1 The groundwater level in December declinedinitially and then increased without rainfall recharge whichmeant that except rainfall there were also other factors thataffected groundwater levelThe nearby Liangduo River or theYellow Sea may have had an effect on the fluctuation withoutprecipitation events
Linear regression analysis was performed to investigatethe relationships among precipitation evaporation riverstage sea tide level and groundwater level The methodwas used to identify the effective factors on groundwaterlevel (Figure 4) In this method 1198772 values were analyzedand the 1198772 values indicated correlations between ground-water level and the influence factors The 1198772 values amongprecipitation evaporation river stage sea tide level andgroundwater level ranged from 0004 to 0824 The outputshowed that precipitation evaporation and river stage were
4 Journal of Chemistry
0
50
100
150
200
250
Gro
undw
ater
leve
l (cm
)
Data (ymd)
July
1 2
013
Augu
st 1
201
3
Sept
embe
r 1 2
013
Oct
ober
1 2
013
Nov
embe
r 1 2
013
Dec
embe
r 1 2
013
80
70
60
50
40
30
20
10
0
minus10
Prec
ipita
tion
(cm
)
Groundwater levelPrecipitation
(a)
0
50
100
150
200
250
Gro
undw
ater
leve
l (cm
)
8
7
6
5
4
3
2
1
0
minus1
Evap
orat
ion
(cm
)
Groundwater levelEvaporation
Data (ymd)
July
1 2
013
Augu
st 1
201
3
Sept
embe
r 1 2
013
Oct
ober
1 2
013
Nov
embe
r 1 2
013
Dec
embe
r 1 2
013
(b)
Figure 3 Groundwater fluctuation with precipitation and evaporation data from July 1 to December 31 2013
significant (119875 lt 001) effective on groundwater level in thestudy area The fitting curve showed positive correlationsamong groundwater level precipitation and river stage aswell as a negative correlation between groundwater leveland evaporation Estimating a dependent variable which isprecipitation largely contributed to obtaining groundwaterlevel with the highest 1198772 value The order of the influencingfactors on groundwater level was precipitation gt river stage gtevaporationThe sea tide level did not affect the groundwaterlevel (119875 gt 005)
The result indicates that precipitation mainly drivesdynamic changes in groundwater level in this study areaThe groundwater level exhibited multipeak curves and ashallower water level during the wet season than duringthe dry season because of frequent precipitation eventsDuring the dry season without rainfall the groundwater levelfluctuated because of fluctuations in the LiangduoRiver stageRiver stage had effect on groundwater level The tide level ofthe Yellow Sea had no influence on the groundwater level
32 Variations in Groundwater Salinity Groundwater salin-ity was generally affected by precipitation The statisticalvalues of precipitation and groundwater salinity are listed inTable 1 and the results are presented in Figure 5
The salinity data curve can be divided into two parts PartI showed the data curve from July to October (wet season)wherein the groundwater salinity fluctuated according to pre-cipitating events The groundwater salinity was reduced afterprecipitation events and then began to increase graduallyuntil the next event Small increases of salinity during majorrainfall intervals in Figure 5 may suggest that evaporationfails to accumulate salinity due to rainfall washout Thefluctuation in the groundwater salinity could be related toprecipitation events Part II showed the data curve from
November to December (dry season) wherein the amountof rainfall was lower than that during the wet seasonThe groundwater salinity showed increasing trends in earlyNovember and then sharply increased in late November Thegroundwater salinity increased with time and reached itsmaximum level (2445 gkg) in December
Table 1 shows that the groundwater salinity increasedas monthly precipitation decreased In July with abundantprecipitation the groundwater salinitywas only 087 gkg thelowest salinity level in the study time seriesThe groundwatersalinity increased each month until the maximum monthlyaverage was reached in December The groundwater salinityin December was approximately 23 times higher than that inJuly
Table 2 shows the 27 precipitation events that occurredduring the study series Changing percentage is a ratio whichis the differential value between groundwater salinity beforeand after rainfall divided by groundwater salinity beforerainfall The 1198772 value between precipitation and changingpercentage of groundwater salinity is 0653 which is signif-icant at the 001 level Precipitation influenced salt dilutionin groundwater A sufficient amount of rainfall diluted salt ingroundwater and decreased the groundwater salinity Inade-quate rainfall had no effect on decreasing the groundwatersalinity The highest rainfall of 744 cm did not cause ahigh percentage of change The highest change percentage ofgroundwater salinity was caused by a 603 cm precipitationevent and the 33 cm precipitation event the next day resultedin a 4522 change percentage The changing percentage wasrelated not only to rainfall but also to groundwater leveland the initial value of groundwater salinity The individualand small amount of rainfall had minimal or no effect ondecreasing the groundwater salinity particularly during thedry season Rainfalls were all less than 85 cm during the
Journal of Chemistry 5
200
100
0
0 10 20 30 40 50 60 70 80
Precipitation (cm)
Gro
undw
ater
fluc
tuat
ion
(cm
)
R2= 0833 P lt 001
minus10
(a)
Gro
undw
ater
fluc
tuat
ion
(cm
)
0
minus20
minus40
minus1 0 1 2 3 4 5 6 7 8
Evaporation (cm)
R2= 0235 P gt 005
(b)
0
minus100
minus200
150 200 250
River level (cm)
Gro
undw
ater
leve
l (cm
)
R2= 0346 P lt 001
(c)
0
minus100
minus200
Gro
undw
ater
leve
l (cm
)
minus50 0 50 100 150 200 250 300 350 400
Sea tide level (cm)
R2= 0004 P gt 005
(d)
Figure 4 Linear regressions among precipitation evaporation river stage sea tide level and groundwater level
Table 1 Monthly precipitation and evaporation and monthly average groundwater salinity and level seasonal precipitation and evaporationand average of groundwater salinity and level
Wet season Dry season Standard varianceJuly August September October November December
dry season and no rainfall recharged the groundwater inDecember groundwater salinity increasedThe groundwatersalinity sharply increased during the dry season when noprecipitation event occurred
33 Variations in Groundwater Salinity with GroundwaterLevel As analyzed in the preceding sections rainfall causedthe groundwater level and salinity to fluctuate and ground-water salinity was low when the amount of rainfall was
large After the decreasing of groundwater salinity causedby rainfall between two continuous precipitation eventsgroundwater salinity increased with the lowering of waterlevels Our findings suggest that salt movement is closelyrelated to the groundwater table
In different seasons the groundwater salinity exhibiteddifferent trends as the groundwater level changed as shownin Figure 6 Praveena et al indicated that high evaporationin areas with shallow groundwater tables may also lead to
6 Journal of Chemistry
Table 2 Changing percentage of groundwater salinity according to precipitation
Figure 5 Variations in groundwater salinity and precipitation fromJuly 1 to December 31 2013
salinization [7] During the wet season with high precip-itation and evaporation the groundwater level fluctuatedfrequently in a wide range and the groundwater salinityfluctuated synchronously with the groundwater level but thetrend appeared inversely
During the observation period the correlation coefficientbetween the groundwater level and salinity was 0324 andwas significantly correlated at the 001 level The correlationcoefficients from wet to dry seasons were 0259 and 0529respectively and both were significantly correlated at the 001level This finding suggested that the groundwater salinityis associated with the groundwater level The correlationcoefficient during the wet season was lower than that duringthe dry season Without the influence of precipitation events
a higher correlation between groundwater salinity and levelwas observed
From November to December the total rainfall wasonly 192 cm which occurred in early November Theseprecipitation events resulted in small groundwater levelfluctuations (Figure 6) The groundwater salinity curve didnot exhibit any noticeable fluctuation suggesting that thesmall amount of rainfall did not affect the groundwatersalinity After the precipitation events the groundwater tableremained relatively stable The groundwater level fluctuationinterval was 172 cm to 210 cm During this nonrainfall periodthe variations in groundwater salinity were not similar tothose at the groundwater level The groundwater salinityincreased suddenly in lateNovember before entering a periodof sustained and rapid growth Linear fits were conductedon groundwater salinity in early November and from lateNovember to December The linear fit equations were 119910 =0029119909 + 2649 and 119910 = 0528119909 + 3991 respectively Thegrowth rates of salinity were compared with the latter periodshowing higher levels than the former Without precipitationdilution shallow groundwater salinity increased continu-ously during the dry season
4 Discussion
The precipitation evaporation and groundwater level valuesare reported in Table 1 The time series shows that thewet season precipitation is significantly higher than thatduring the dry season accounting for 95 percent of totalprecipitation The evaporation and groundwater levels in thewet season are 5 times and 35 cm higher than those in the dryseason respectively
41 Effects of Precipitation River Stage and Evaporation onDynamics of Groundwater Level Thedynamics of groundwa-ter level in the study area are affectedmainly by precipitationwater level of nearby river and evaporation It was affected
Journal of Chemistry 7
25
20
15
10
5
0
Gro
undw
ater
salin
ity (g
kg)
0
50
100
150
200
250
Gro
undw
ater
leve
l (cm
)
Groundwater salinityGroundwater level
Data (ymd)
July
1 2
013
Augu
st 1
201
3
Sept
embe
r 1 2
013
Oct
ober
1 2
013
Nov
embe
r 1 2
013
Dec
embe
r 1 2
013
Figure 6 Variations in groundwater salinity with groundwater levelfluctuation
by precipitation evaporation and river stage Dogan et alApaydin Jan et al Hong and Wan and Carretero and Krusefound that precipitation was one of the dominant factors thatcontributed to groundwater level fluctuation [13 15ndash18] Inour study the groundwater levels quickly changed followingeach precipitation event After rainfall the groundwater levelpresented a linear downward trend because of evaporationuntil the next precipitation event occurred The groundwaterlevel was affected not only by precipitation and evaporationbut also by the river stage
42 Effects of Precipitation Dilution on Dynamics of Ground-water Salinity The groundwater salinity can be reduced afterthe recharge of precipitation events Research showed thatthe groundwater salinity changes according to precipita-tion events Wang et al pointed out that the precipitationinfiltrated and leached downward to recharge groundwaterwhich could refresh and dilute the salt of the soil wateror groundwater during the rainy season [6] Wang et alobserved that during dry seasons shallow groundwaterwould be sanitized because of the evaporation and conden-sation effects in the north China plain [6] Rabbani et alconfirmed that saline water starts to penetrate inland duringwinter months when river flow is low and groundwaterlevel decreases as a result of climate change in Bangladesh[12] These studies indicated that the shallow groundwatersalinity would increase by evaporation in the condition ofno precipitation or saline water penetrating In our studyhigh precipitation decreased the salinity concentration ingroundwater during the wet season and continues evapo-ration increase salinity dramatically during the dry seasonThe amount of precipitation serves an important function insalt dilution Taking advantage of precipitation can be a goodmethod to control groundwater salinity in a coastal plain
43 Variations in Groundwater Level Influence on Ground-water Salinity According to the entire study time seriesgroundwater salinity changed according to the fluctuationof groundwater level During the dry season the correlationcoefficient between the groundwater level and salinity washigher than that during the wet season The fluctuationsof groundwater level were mainly caused by precipitationand evaporation in wet season while in dry season thegroundwater level was mainly affected by the water level ofLiangduo River and groundwater salinity concentration wasincreased sharply by seawater intrusion Zhou et al foundthat the saltwater intrusion is mainly controlled by riverdischarge and tidal current in Zhujiang River Estuary [19] Itis also related to wind amplitude and direction and sea levelrising A deep mechanism of saltwater intrusion should beinvestigated For a clearer mechanism of saltwater intrusionin this study area not only climate factors but also moreinfluencing factors as above can be researched And spatialanalysis should be focused on
5 Conclusions
In coastal plain of eastern China the average depth ofgroundwater level is shallow and easily affected by climatefactors (precipitation and evaporation) and river stage Theinfluencing factors on the groundwater level were in theorder precipitation gt river stage gt evaporation The ground-water salinity is influenced by climate factors groundwaterlevel and seawater intrusion Precipitation infiltrated intogroundwater and diluted the salinity so the groundwatersalinity fluctuated with precipitation events Between twoprecipitation events groundwater salinity increased withevaporation Groundwater salinity changed with the fluctu-ation of groundwater level and significant correlation wasfound between them (119875 lt 001) In the study periodthe groundwater salinity fluctuated frequently During wetseason it maintained in a low salinity level It increasedcontinuously and reached a maximum value in Decemberduring the dry season The result indicated that seawaterintrusion occurred in the coastal plain in dry season
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
This study was financially supported by the Public WelfareIndustry Special Funds for Scientific Research Projects of theMinistry of Water Resources (Grant no 200801025) and theInnovative Project of Scientific Research for Postgraduatesin Ordinary Universities in Jiangsu Province (Grant noCXZZ13 0267) The authors thank Jiangsu Province Hydrol-ogy and Water Resources Investigation Bureau for providingthem with climate data
8 Journal of Chemistry
References
[1] P KumarM Tsujimura TNakano andTMinoru ldquoTime seriesanalysis for the estimation of tidal fluctuation effect on differentaquifers in a small coastal area of Saijo plain Ehime prefectureJapanrdquo Environmental Geochemistry and Health vol 35 no 2pp 239ndash250 2013
[2] M A T M T Rahman R K Majumder S H Rahmanand M A Halim ldquoSources of deep groundwater salinity inthe southwestern zone of Bangladeshrdquo Environmental EarthSciences vol 63 no 2 pp 363ndash373 2011
[3] Y Iwasaki M Ozaki K Nakamura H Horino and SKawashima ldquoRelationship between increment of groundwaterlevel at the beginning of irrigation period and paddy filed areain the Tedori River Alluvial Fan Area Japanrdquo Paddy and WaterEnvironment vol 11 no 1mdash4 pp 551ndash558 2013
[4] Z Chen S E Grasby and K G Osadetz ldquoRelation between cli-mate variability and groundwater levels in the upper carbonateaquifer southern Manitoba Canadardquo Journal of Hydrology vol290 no 1-2 pp 43ndash62 2004
[5] Z Chen S E Grasby and K G Osadetz ldquoPredicting averageannual groundwater levels from climatic variables an empiricalmodelrdquo Journal of Hydrology vol 260 no 1ndash4 pp 102ndash117 2002
[6] SWang X Song QWang et al ldquoShallow groundwater dynam-ics and origin of salinity at two sites in salinated and water-deficient region of North China Plain Chinardquo EnvironmentalEarth Sciences vol 66 no 3 pp 729ndash739 2012
[7] S M Praveena M H Abdullah K Bidin and A Z ArisldquoUnderstanding of groundwater salinity using statistical mod-eling in a small tropical island EastMalaysiardquo Environmentalistvol 31 no 3 pp 279ndash287 2011
[8] D Liu X Chen and Z Lou ldquoAmodel for the optimal allocationof water resources in a saltwater intrusion area a case study inpearl river delta in Chinardquo Water Resources Management vol24 no 1 pp 63ndash81 2010
[9] Z Li C Zhang and W Zhu ldquoThe present and analysis of thesea water intrusion in coastland of Rizhaordquo Hydrogeology andEngineering Geology vol 36 no 5 pp 129ndash132 2009 (Chinese)
[10] J G Redwood PumpRecharge Rate Affects Saltwater Intrusion2004 httpwwwsolinstcomresourcespapers101c4saltphp
[11] G H P Oude Essink ldquoSalt water intrusion in a three-dimensional groundwater system in the Netherlands a numer-ical studyrdquo Transport in Porous Media vol 43 no 1 pp 137ndash1582001
[12] G Rabbani A A Rahman and N Islam ldquoClimate change andsea level rise issues and challenges for coastal communitiesin the Indian Ocean Regionrdquo in Coastal Zones and ClimateChange D Michel and A Pandya Eds pp 17ndash30 The HenryL Stimson Center Washington DC USA 2010
[13] A Dogan H Demirpence and M Cobaner ldquoPrediction ofgroundwater levels from lake levels and climate data usingANNapproachrdquoWater SA vol 34 no 2 pp 199ndash208 2008
[14] Q Yong Z Zhang Y Fei et al ldquoCalculating precipitationrecharge to groundwater applying envieronmental chloridetracer methodrdquo in Proceedings of the International Symposiumon Water Resource and Environmental Protection (ISWREP rsquo11)vol 1 pp 139ndash143 Xirsquoan China May 2011
[15] A Apaydin ldquoResponse of groundwater to climate variationfluctuations of groundwater level and well yields in the Hala-cli aquifer (Cankiri Turkey)rdquo Environmental Monitoring andAssessment vol 165 no 1ndash4 pp 653ndash663 2010
[16] C-D Jan T-H Chen and H-M Huang ldquoAnalysis of rainfall-induced quick groundwater-level response by using a Kernelfunctionrdquo Paddy and Water Environment vol 11 no 1ndash4 pp135ndash144 2013
[17] Y-M Hong and S Wan ldquoForecasting groundwater level fluctu-ations for rainfall-induced landsliderdquo Natural Hazards vol 57no 2 pp 167ndash184 2011
[18] S C Carretero and E E Kruse ldquoRelationship between precip-itation and water-table fluctuation in a coastal dune aquiferNortheastern coast of the Buenos Aires province ArgentinardquoHydrogeology Journal vol 20 no 8 pp 1613ndash1621 2012
[19] W Zhou D Wang and L Luo ldquoInvestigation of saltwaterintrusion and salinity stratification in winter of 20072008 inthe Zhujiang River Estuary in ChinardquoActa Oceanologica Sinicavol 31 no 3 pp 31ndash46 2012
change and sea level rise exacerbated saltwater intrusionthereby jeopardizing water use safety especially during thedry season [8] Saltwater intrusion can degrade water qualityand reduce available water if insufficient freshwater are enter-ing the groundwater system and it becamemore serious thanit was before particularly in delta areas because of climatechange [8] Saltwater intrusion occurred globally in morethan 50 countries and regions particularly North Africathe Middle East the Mediterranean China Mexico andthe Atlantic and Gulf Coasts of the United States includingSouthernCalifornia [9 10] Saltwater intrusion can negativelyaffect coastal ecosystems in terms of freshwater quality andthe dynamics of plant community Along with saltwaterintrusion salinization of the groundwater systems may affectagriculture and domestic and industrial water supplies [11]Extensive researches were conducted worldwide to under-stand the mechanisms of saltwater intrusion Environmentalconditions such as precipitation and evapotranspiration wereclustered with hydraulic heads to show that they also influ-ence salinity concentration in groundwater [7] In someplaceseawater intrusion affects groundwater salinity in particularseason For example Rabbani et al confirmed that salinewater starts to penetrate inland during winter months [12] Itis necessary to know the seasonal variations in groundwatersalinity
Groundwater plays a crucial role in the socioeconomicdevelopment of Jiangsu coastal plain a developed area ineastern China In this place shallow groundwater is easilyaffected by environment such as climate change river stageandYellow Sea tidal levelWith a growing population Jiangsufaces an increasing demand for freshwater For solving thisproblem deeply understanding the groundwater system andits influencing factors is necessary Then the relationshipsamong the groundwater level and climate factors river stageYellow Sea tide level and variations in groundwater salinityin this area have not been studied
Thus the purpose of this present study was to investigatethe seasonal variations of groundwater level and salinity inJiangsu coastal plain Specific objectives were (1) to detectthe dynamics of groundwater level and salinity in wet anddry season (2) to determine the relationships among thegroundwater level salinity content climate factors (precipi-tation and evaporation) river stage and Yellow Sea tide levelThis study can provide a management method for coastalplain groundwater by analyzing the factors that influence thegroundwater level and the changing trends of groundwatersalinity
2 Materials and Methods
21 Study Site Description Observational data on thegroundwater level and salinity in Dongtai (120∘071015840sim120∘531015840 Eand 32∘331015840sim32∘571015840 N) Jiangsu in eastern China were collectedand investigated (Figure 1) Jiangsu coastal plain lies to thewest of the Yellow Sea at an altitude ranging from 26m to46m above sea level Dongtai city is in the east of Jiangsuprovince and adjacent to the Yellow Sea The plain sandyarea has a highly permeable soil that consists of mealy sand
and extremely fine sand particles The phreatic surface isat a shallow depth generally 1m to 3m and even 02mafter rainfall below the ground surface The average annualtemperature average annual rainfall and evaporation rateare approximately 150∘C 10598mm and 10067mm respec-tively During the study period in 2013 the annual meanprecipitation was approximately 859mm The maximumprecipitation is recorded in July before gradually decreasingThe annual evaporation is approximately 6515mm Over50 of the rainfall falls between July and October Mostrainfall in the summer is in the form of local showers andthunderstorms and in winter the rainfall amount is small
Considering that most rainfall falls between July andOctober and very small amount of rainfall falls betweenNovember and December in this place July to October isrecognized as the wet season and November to December isthe dry season
22 Experiment Design A farmland covering an area of 50mtimes 100m was selected as a typical saline groundwater site witha shallow water table to study the water and salt dynamicsduring different seasons The farmland was bulldozed bymachine to make sure the land is flat and there is novegetation in the farmland The farmland is approximately5 km away from the Yellow Sea and 2 km away fromLiangduoRiver Nine shallow monitoring wells were constructed andinstalled to a depth of 5m in the aquifer of the farmland(Figure 2)
Data on daily precipitation evaporation river stage andthe Yellow Sea tide level were gathered from the LiangduoRiver dam monitoring point of Jiangsu Province Hydrologyand Water Resources Investigation Bureau which is locatedaround 15 km northeast of the farmland Precipitation datawere collected using a rain gauge and evaporation wasmeasured using an E601 evaporation pan Mean daily riverstage and survey of tide data were recorded manually andautomatically using a groundwater levelmonitoring system atLiangduo River dam The recorded groundwater levels werebased on the 1985Yellow Sea elevation All datawere collectedfrom July 1 2013 to December 31 2013
Manualmonitoring logger was set to observe the ground-water table and groundwater samples collected daily fromthe nine wells spread in the area The recorded water levelsare below the 1985 height of the Yellow Sea Each sampleof 100mL was collected from the upper monitor well Dailygroundwater level and salinity from all wells were monitoredmanually and analyzed The groundwater level of nine wellshad the same trendThe average value of the daily groundwa-ter level and salinity of nine wells were obtained from July 12013 to December 31 2013 The salinity value was calibratedunder 25∘C
3 Results
31 Variations in Groundwater Level The average depthof groundwater in the study area was 17m In the dailygroundwater fluctuation figure the shallowest groundwaterlevel and the deepest groundwater level were identified The
Journal of Chemistry 3
JiangsuHuang He
China
Mongolia
Japan
KoreaRepublic of Korea
Yellow SeaEast China Sea
South China Sea
(km)
BoundaryRiver
SeaJiangsu province
N
0 1000 2000500
Yang
tze
(a)
Dongtai
The farmlandLiangduo River management
Liangduo River
Jiangsu
Dongtai
N
Yellow Sea
5km
0 5 10 20
(km)
BoundaryRiver
SeaJiangsu province
(b)
Figure 1 Geographical location of the study area (a) Jiangsu province in China (b) Dongtai city of Jiangsu province and the farmland
Observational well
The farmland
0 5 10 20
(m)
N
Figure 2 Distribution of the observation wells
first situation corresponded to one of the shallowest waterlevels (on October 8) and the other to the deepest one onAugust 24 (Figure 3)The shallowest and deepest water levelswere 24 cm and 254 cm respectively
The main factors that affected groundwater interac-tion were the climate parameters (rainfall and evaporationdemand) [13] Precipitation infiltration was a key rechargesource of shallow groundwater as well as the major rechargesource of groundwater [14] We observed that the groundwa-ter level exhibited multipeak and multivalley curves and thefluctuation cycle of groundwater synchronized with precip-itation events (Figure 3(a)) During the wet season frequentand sufficient rainfall led to large fluctuations in groundwaterlevel and the shallowest water level was reached As indicatedin Figure 3(a) the fluctuation range related to rainfall peakedat 188 cm after heavy rain with 744 cm precipitation onAugust 24 and a day of precipitation infiltration During
the dry season the groundwater level fluctuated within anarrow range with low precipitation During a nonrainfallperiod the groundwater level exhibited a linear downwardtrend because of evaporation and then increased until thenext precipitation occurred (Figures 3(a) and 3(b)) Theperiod from August 1 to 19 is characterized by absence ofrainfall together with elevated temperatures and potentialevapotranspiration the longest nonrainfall period during thewet season occurred During this period the groundwaterlevel reduced by 175 cmThegroundwater level increased afterthe precipitation events and then decreased gradually withevaporationThe groundwater tables variedwithin the periodfrom wet to dry seasons and showed seasonal variationsbecause of the seasonal distribution of precipitation andevaporation
In the condition of wake evaporation in Decemberdownward trend of groundwater level was not obvious andeven the level on December 31 was 3 cm shallower thanDecember 1 The groundwater level in December declinedinitially and then increased without rainfall recharge whichmeant that except rainfall there were also other factors thataffected groundwater levelThe nearby Liangduo River or theYellow Sea may have had an effect on the fluctuation withoutprecipitation events
Linear regression analysis was performed to investigatethe relationships among precipitation evaporation riverstage sea tide level and groundwater level The methodwas used to identify the effective factors on groundwaterlevel (Figure 4) In this method 1198772 values were analyzedand the 1198772 values indicated correlations between ground-water level and the influence factors The 1198772 values amongprecipitation evaporation river stage sea tide level andgroundwater level ranged from 0004 to 0824 The outputshowed that precipitation evaporation and river stage were
4 Journal of Chemistry
0
50
100
150
200
250
Gro
undw
ater
leve
l (cm
)
Data (ymd)
July
1 2
013
Augu
st 1
201
3
Sept
embe
r 1 2
013
Oct
ober
1 2
013
Nov
embe
r 1 2
013
Dec
embe
r 1 2
013
80
70
60
50
40
30
20
10
0
minus10
Prec
ipita
tion
(cm
)
Groundwater levelPrecipitation
(a)
0
50
100
150
200
250
Gro
undw
ater
leve
l (cm
)
8
7
6
5
4
3
2
1
0
minus1
Evap
orat
ion
(cm
)
Groundwater levelEvaporation
Data (ymd)
July
1 2
013
Augu
st 1
201
3
Sept
embe
r 1 2
013
Oct
ober
1 2
013
Nov
embe
r 1 2
013
Dec
embe
r 1 2
013
(b)
Figure 3 Groundwater fluctuation with precipitation and evaporation data from July 1 to December 31 2013
significant (119875 lt 001) effective on groundwater level in thestudy area The fitting curve showed positive correlationsamong groundwater level precipitation and river stage aswell as a negative correlation between groundwater leveland evaporation Estimating a dependent variable which isprecipitation largely contributed to obtaining groundwaterlevel with the highest 1198772 value The order of the influencingfactors on groundwater level was precipitation gt river stage gtevaporationThe sea tide level did not affect the groundwaterlevel (119875 gt 005)
The result indicates that precipitation mainly drivesdynamic changes in groundwater level in this study areaThe groundwater level exhibited multipeak curves and ashallower water level during the wet season than duringthe dry season because of frequent precipitation eventsDuring the dry season without rainfall the groundwater levelfluctuated because of fluctuations in the LiangduoRiver stageRiver stage had effect on groundwater level The tide level ofthe Yellow Sea had no influence on the groundwater level
32 Variations in Groundwater Salinity Groundwater salin-ity was generally affected by precipitation The statisticalvalues of precipitation and groundwater salinity are listed inTable 1 and the results are presented in Figure 5
The salinity data curve can be divided into two parts PartI showed the data curve from July to October (wet season)wherein the groundwater salinity fluctuated according to pre-cipitating events The groundwater salinity was reduced afterprecipitation events and then began to increase graduallyuntil the next event Small increases of salinity during majorrainfall intervals in Figure 5 may suggest that evaporationfails to accumulate salinity due to rainfall washout Thefluctuation in the groundwater salinity could be related toprecipitation events Part II showed the data curve from
November to December (dry season) wherein the amountof rainfall was lower than that during the wet seasonThe groundwater salinity showed increasing trends in earlyNovember and then sharply increased in late November Thegroundwater salinity increased with time and reached itsmaximum level (2445 gkg) in December
Table 1 shows that the groundwater salinity increasedas monthly precipitation decreased In July with abundantprecipitation the groundwater salinitywas only 087 gkg thelowest salinity level in the study time seriesThe groundwatersalinity increased each month until the maximum monthlyaverage was reached in December The groundwater salinityin December was approximately 23 times higher than that inJuly
Table 2 shows the 27 precipitation events that occurredduring the study series Changing percentage is a ratio whichis the differential value between groundwater salinity beforeand after rainfall divided by groundwater salinity beforerainfall The 1198772 value between precipitation and changingpercentage of groundwater salinity is 0653 which is signif-icant at the 001 level Precipitation influenced salt dilutionin groundwater A sufficient amount of rainfall diluted salt ingroundwater and decreased the groundwater salinity Inade-quate rainfall had no effect on decreasing the groundwatersalinity The highest rainfall of 744 cm did not cause ahigh percentage of change The highest change percentage ofgroundwater salinity was caused by a 603 cm precipitationevent and the 33 cm precipitation event the next day resultedin a 4522 change percentage The changing percentage wasrelated not only to rainfall but also to groundwater leveland the initial value of groundwater salinity The individualand small amount of rainfall had minimal or no effect ondecreasing the groundwater salinity particularly during thedry season Rainfalls were all less than 85 cm during the
Journal of Chemistry 5
200
100
0
0 10 20 30 40 50 60 70 80
Precipitation (cm)
Gro
undw
ater
fluc
tuat
ion
(cm
)
R2= 0833 P lt 001
minus10
(a)
Gro
undw
ater
fluc
tuat
ion
(cm
)
0
minus20
minus40
minus1 0 1 2 3 4 5 6 7 8
Evaporation (cm)
R2= 0235 P gt 005
(b)
0
minus100
minus200
150 200 250
River level (cm)
Gro
undw
ater
leve
l (cm
)
R2= 0346 P lt 001
(c)
0
minus100
minus200
Gro
undw
ater
leve
l (cm
)
minus50 0 50 100 150 200 250 300 350 400
Sea tide level (cm)
R2= 0004 P gt 005
(d)
Figure 4 Linear regressions among precipitation evaporation river stage sea tide level and groundwater level
Table 1 Monthly precipitation and evaporation and monthly average groundwater salinity and level seasonal precipitation and evaporationand average of groundwater salinity and level
Wet season Dry season Standard varianceJuly August September October November December
dry season and no rainfall recharged the groundwater inDecember groundwater salinity increasedThe groundwatersalinity sharply increased during the dry season when noprecipitation event occurred
33 Variations in Groundwater Salinity with GroundwaterLevel As analyzed in the preceding sections rainfall causedthe groundwater level and salinity to fluctuate and ground-water salinity was low when the amount of rainfall was
large After the decreasing of groundwater salinity causedby rainfall between two continuous precipitation eventsgroundwater salinity increased with the lowering of waterlevels Our findings suggest that salt movement is closelyrelated to the groundwater table
In different seasons the groundwater salinity exhibiteddifferent trends as the groundwater level changed as shownin Figure 6 Praveena et al indicated that high evaporationin areas with shallow groundwater tables may also lead to
6 Journal of Chemistry
Table 2 Changing percentage of groundwater salinity according to precipitation
Figure 5 Variations in groundwater salinity and precipitation fromJuly 1 to December 31 2013
salinization [7] During the wet season with high precip-itation and evaporation the groundwater level fluctuatedfrequently in a wide range and the groundwater salinityfluctuated synchronously with the groundwater level but thetrend appeared inversely
During the observation period the correlation coefficientbetween the groundwater level and salinity was 0324 andwas significantly correlated at the 001 level The correlationcoefficients from wet to dry seasons were 0259 and 0529respectively and both were significantly correlated at the 001level This finding suggested that the groundwater salinityis associated with the groundwater level The correlationcoefficient during the wet season was lower than that duringthe dry season Without the influence of precipitation events
a higher correlation between groundwater salinity and levelwas observed
From November to December the total rainfall wasonly 192 cm which occurred in early November Theseprecipitation events resulted in small groundwater levelfluctuations (Figure 6) The groundwater salinity curve didnot exhibit any noticeable fluctuation suggesting that thesmall amount of rainfall did not affect the groundwatersalinity After the precipitation events the groundwater tableremained relatively stable The groundwater level fluctuationinterval was 172 cm to 210 cm During this nonrainfall periodthe variations in groundwater salinity were not similar tothose at the groundwater level The groundwater salinityincreased suddenly in lateNovember before entering a periodof sustained and rapid growth Linear fits were conductedon groundwater salinity in early November and from lateNovember to December The linear fit equations were 119910 =0029119909 + 2649 and 119910 = 0528119909 + 3991 respectively Thegrowth rates of salinity were compared with the latter periodshowing higher levels than the former Without precipitationdilution shallow groundwater salinity increased continu-ously during the dry season
4 Discussion
The precipitation evaporation and groundwater level valuesare reported in Table 1 The time series shows that thewet season precipitation is significantly higher than thatduring the dry season accounting for 95 percent of totalprecipitation The evaporation and groundwater levels in thewet season are 5 times and 35 cm higher than those in the dryseason respectively
41 Effects of Precipitation River Stage and Evaporation onDynamics of Groundwater Level Thedynamics of groundwa-ter level in the study area are affectedmainly by precipitationwater level of nearby river and evaporation It was affected
Journal of Chemistry 7
25
20
15
10
5
0
Gro
undw
ater
salin
ity (g
kg)
0
50
100
150
200
250
Gro
undw
ater
leve
l (cm
)
Groundwater salinityGroundwater level
Data (ymd)
July
1 2
013
Augu
st 1
201
3
Sept
embe
r 1 2
013
Oct
ober
1 2
013
Nov
embe
r 1 2
013
Dec
embe
r 1 2
013
Figure 6 Variations in groundwater salinity with groundwater levelfluctuation
by precipitation evaporation and river stage Dogan et alApaydin Jan et al Hong and Wan and Carretero and Krusefound that precipitation was one of the dominant factors thatcontributed to groundwater level fluctuation [13 15ndash18] Inour study the groundwater levels quickly changed followingeach precipitation event After rainfall the groundwater levelpresented a linear downward trend because of evaporationuntil the next precipitation event occurred The groundwaterlevel was affected not only by precipitation and evaporationbut also by the river stage
42 Effects of Precipitation Dilution on Dynamics of Ground-water Salinity The groundwater salinity can be reduced afterthe recharge of precipitation events Research showed thatthe groundwater salinity changes according to precipita-tion events Wang et al pointed out that the precipitationinfiltrated and leached downward to recharge groundwaterwhich could refresh and dilute the salt of the soil wateror groundwater during the rainy season [6] Wang et alobserved that during dry seasons shallow groundwaterwould be sanitized because of the evaporation and conden-sation effects in the north China plain [6] Rabbani et alconfirmed that saline water starts to penetrate inland duringwinter months when river flow is low and groundwaterlevel decreases as a result of climate change in Bangladesh[12] These studies indicated that the shallow groundwatersalinity would increase by evaporation in the condition ofno precipitation or saline water penetrating In our studyhigh precipitation decreased the salinity concentration ingroundwater during the wet season and continues evapo-ration increase salinity dramatically during the dry seasonThe amount of precipitation serves an important function insalt dilution Taking advantage of precipitation can be a goodmethod to control groundwater salinity in a coastal plain
43 Variations in Groundwater Level Influence on Ground-water Salinity According to the entire study time seriesgroundwater salinity changed according to the fluctuationof groundwater level During the dry season the correlationcoefficient between the groundwater level and salinity washigher than that during the wet season The fluctuationsof groundwater level were mainly caused by precipitationand evaporation in wet season while in dry season thegroundwater level was mainly affected by the water level ofLiangduo River and groundwater salinity concentration wasincreased sharply by seawater intrusion Zhou et al foundthat the saltwater intrusion is mainly controlled by riverdischarge and tidal current in Zhujiang River Estuary [19] Itis also related to wind amplitude and direction and sea levelrising A deep mechanism of saltwater intrusion should beinvestigated For a clearer mechanism of saltwater intrusionin this study area not only climate factors but also moreinfluencing factors as above can be researched And spatialanalysis should be focused on
5 Conclusions
In coastal plain of eastern China the average depth ofgroundwater level is shallow and easily affected by climatefactors (precipitation and evaporation) and river stage Theinfluencing factors on the groundwater level were in theorder precipitation gt river stage gt evaporation The ground-water salinity is influenced by climate factors groundwaterlevel and seawater intrusion Precipitation infiltrated intogroundwater and diluted the salinity so the groundwatersalinity fluctuated with precipitation events Between twoprecipitation events groundwater salinity increased withevaporation Groundwater salinity changed with the fluctu-ation of groundwater level and significant correlation wasfound between them (119875 lt 001) In the study periodthe groundwater salinity fluctuated frequently During wetseason it maintained in a low salinity level It increasedcontinuously and reached a maximum value in Decemberduring the dry season The result indicated that seawaterintrusion occurred in the coastal plain in dry season
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
This study was financially supported by the Public WelfareIndustry Special Funds for Scientific Research Projects of theMinistry of Water Resources (Grant no 200801025) and theInnovative Project of Scientific Research for Postgraduatesin Ordinary Universities in Jiangsu Province (Grant noCXZZ13 0267) The authors thank Jiangsu Province Hydrol-ogy and Water Resources Investigation Bureau for providingthem with climate data
8 Journal of Chemistry
References
[1] P KumarM Tsujimura TNakano andTMinoru ldquoTime seriesanalysis for the estimation of tidal fluctuation effect on differentaquifers in a small coastal area of Saijo plain Ehime prefectureJapanrdquo Environmental Geochemistry and Health vol 35 no 2pp 239ndash250 2013
[2] M A T M T Rahman R K Majumder S H Rahmanand M A Halim ldquoSources of deep groundwater salinity inthe southwestern zone of Bangladeshrdquo Environmental EarthSciences vol 63 no 2 pp 363ndash373 2011
[3] Y Iwasaki M Ozaki K Nakamura H Horino and SKawashima ldquoRelationship between increment of groundwaterlevel at the beginning of irrigation period and paddy filed areain the Tedori River Alluvial Fan Area Japanrdquo Paddy and WaterEnvironment vol 11 no 1mdash4 pp 551ndash558 2013
[4] Z Chen S E Grasby and K G Osadetz ldquoRelation between cli-mate variability and groundwater levels in the upper carbonateaquifer southern Manitoba Canadardquo Journal of Hydrology vol290 no 1-2 pp 43ndash62 2004
[5] Z Chen S E Grasby and K G Osadetz ldquoPredicting averageannual groundwater levels from climatic variables an empiricalmodelrdquo Journal of Hydrology vol 260 no 1ndash4 pp 102ndash117 2002
[6] SWang X Song QWang et al ldquoShallow groundwater dynam-ics and origin of salinity at two sites in salinated and water-deficient region of North China Plain Chinardquo EnvironmentalEarth Sciences vol 66 no 3 pp 729ndash739 2012
[7] S M Praveena M H Abdullah K Bidin and A Z ArisldquoUnderstanding of groundwater salinity using statistical mod-eling in a small tropical island EastMalaysiardquo Environmentalistvol 31 no 3 pp 279ndash287 2011
[8] D Liu X Chen and Z Lou ldquoAmodel for the optimal allocationof water resources in a saltwater intrusion area a case study inpearl river delta in Chinardquo Water Resources Management vol24 no 1 pp 63ndash81 2010
[9] Z Li C Zhang and W Zhu ldquoThe present and analysis of thesea water intrusion in coastland of Rizhaordquo Hydrogeology andEngineering Geology vol 36 no 5 pp 129ndash132 2009 (Chinese)
[10] J G Redwood PumpRecharge Rate Affects Saltwater Intrusion2004 httpwwwsolinstcomresourcespapers101c4saltphp
[11] G H P Oude Essink ldquoSalt water intrusion in a three-dimensional groundwater system in the Netherlands a numer-ical studyrdquo Transport in Porous Media vol 43 no 1 pp 137ndash1582001
[12] G Rabbani A A Rahman and N Islam ldquoClimate change andsea level rise issues and challenges for coastal communitiesin the Indian Ocean Regionrdquo in Coastal Zones and ClimateChange D Michel and A Pandya Eds pp 17ndash30 The HenryL Stimson Center Washington DC USA 2010
[13] A Dogan H Demirpence and M Cobaner ldquoPrediction ofgroundwater levels from lake levels and climate data usingANNapproachrdquoWater SA vol 34 no 2 pp 199ndash208 2008
[14] Q Yong Z Zhang Y Fei et al ldquoCalculating precipitationrecharge to groundwater applying envieronmental chloridetracer methodrdquo in Proceedings of the International Symposiumon Water Resource and Environmental Protection (ISWREP rsquo11)vol 1 pp 139ndash143 Xirsquoan China May 2011
[15] A Apaydin ldquoResponse of groundwater to climate variationfluctuations of groundwater level and well yields in the Hala-cli aquifer (Cankiri Turkey)rdquo Environmental Monitoring andAssessment vol 165 no 1ndash4 pp 653ndash663 2010
[16] C-D Jan T-H Chen and H-M Huang ldquoAnalysis of rainfall-induced quick groundwater-level response by using a Kernelfunctionrdquo Paddy and Water Environment vol 11 no 1ndash4 pp135ndash144 2013
[17] Y-M Hong and S Wan ldquoForecasting groundwater level fluctu-ations for rainfall-induced landsliderdquo Natural Hazards vol 57no 2 pp 167ndash184 2011
[18] S C Carretero and E E Kruse ldquoRelationship between precip-itation and water-table fluctuation in a coastal dune aquiferNortheastern coast of the Buenos Aires province ArgentinardquoHydrogeology Journal vol 20 no 8 pp 1613ndash1621 2012
[19] W Zhou D Wang and L Luo ldquoInvestigation of saltwaterintrusion and salinity stratification in winter of 20072008 inthe Zhujiang River Estuary in ChinardquoActa Oceanologica Sinicavol 31 no 3 pp 31ndash46 2012
Figure 1 Geographical location of the study area (a) Jiangsu province in China (b) Dongtai city of Jiangsu province and the farmland
Observational well
The farmland
0 5 10 20
(m)
N
Figure 2 Distribution of the observation wells
first situation corresponded to one of the shallowest waterlevels (on October 8) and the other to the deepest one onAugust 24 (Figure 3)The shallowest and deepest water levelswere 24 cm and 254 cm respectively
The main factors that affected groundwater interac-tion were the climate parameters (rainfall and evaporationdemand) [13] Precipitation infiltration was a key rechargesource of shallow groundwater as well as the major rechargesource of groundwater [14] We observed that the groundwa-ter level exhibited multipeak and multivalley curves and thefluctuation cycle of groundwater synchronized with precip-itation events (Figure 3(a)) During the wet season frequentand sufficient rainfall led to large fluctuations in groundwaterlevel and the shallowest water level was reached As indicatedin Figure 3(a) the fluctuation range related to rainfall peakedat 188 cm after heavy rain with 744 cm precipitation onAugust 24 and a day of precipitation infiltration During
the dry season the groundwater level fluctuated within anarrow range with low precipitation During a nonrainfallperiod the groundwater level exhibited a linear downwardtrend because of evaporation and then increased until thenext precipitation occurred (Figures 3(a) and 3(b)) Theperiod from August 1 to 19 is characterized by absence ofrainfall together with elevated temperatures and potentialevapotranspiration the longest nonrainfall period during thewet season occurred During this period the groundwaterlevel reduced by 175 cmThegroundwater level increased afterthe precipitation events and then decreased gradually withevaporationThe groundwater tables variedwithin the periodfrom wet to dry seasons and showed seasonal variationsbecause of the seasonal distribution of precipitation andevaporation
In the condition of wake evaporation in Decemberdownward trend of groundwater level was not obvious andeven the level on December 31 was 3 cm shallower thanDecember 1 The groundwater level in December declinedinitially and then increased without rainfall recharge whichmeant that except rainfall there were also other factors thataffected groundwater levelThe nearby Liangduo River or theYellow Sea may have had an effect on the fluctuation withoutprecipitation events
Linear regression analysis was performed to investigatethe relationships among precipitation evaporation riverstage sea tide level and groundwater level The methodwas used to identify the effective factors on groundwaterlevel (Figure 4) In this method 1198772 values were analyzedand the 1198772 values indicated correlations between ground-water level and the influence factors The 1198772 values amongprecipitation evaporation river stage sea tide level andgroundwater level ranged from 0004 to 0824 The outputshowed that precipitation evaporation and river stage were
4 Journal of Chemistry
0
50
100
150
200
250
Gro
undw
ater
leve
l (cm
)
Data (ymd)
July
1 2
013
Augu
st 1
201
3
Sept
embe
r 1 2
013
Oct
ober
1 2
013
Nov
embe
r 1 2
013
Dec
embe
r 1 2
013
80
70
60
50
40
30
20
10
0
minus10
Prec
ipita
tion
(cm
)
Groundwater levelPrecipitation
(a)
0
50
100
150
200
250
Gro
undw
ater
leve
l (cm
)
8
7
6
5
4
3
2
1
0
minus1
Evap
orat
ion
(cm
)
Groundwater levelEvaporation
Data (ymd)
July
1 2
013
Augu
st 1
201
3
Sept
embe
r 1 2
013
Oct
ober
1 2
013
Nov
embe
r 1 2
013
Dec
embe
r 1 2
013
(b)
Figure 3 Groundwater fluctuation with precipitation and evaporation data from July 1 to December 31 2013
significant (119875 lt 001) effective on groundwater level in thestudy area The fitting curve showed positive correlationsamong groundwater level precipitation and river stage aswell as a negative correlation between groundwater leveland evaporation Estimating a dependent variable which isprecipitation largely contributed to obtaining groundwaterlevel with the highest 1198772 value The order of the influencingfactors on groundwater level was precipitation gt river stage gtevaporationThe sea tide level did not affect the groundwaterlevel (119875 gt 005)
The result indicates that precipitation mainly drivesdynamic changes in groundwater level in this study areaThe groundwater level exhibited multipeak curves and ashallower water level during the wet season than duringthe dry season because of frequent precipitation eventsDuring the dry season without rainfall the groundwater levelfluctuated because of fluctuations in the LiangduoRiver stageRiver stage had effect on groundwater level The tide level ofthe Yellow Sea had no influence on the groundwater level
32 Variations in Groundwater Salinity Groundwater salin-ity was generally affected by precipitation The statisticalvalues of precipitation and groundwater salinity are listed inTable 1 and the results are presented in Figure 5
The salinity data curve can be divided into two parts PartI showed the data curve from July to October (wet season)wherein the groundwater salinity fluctuated according to pre-cipitating events The groundwater salinity was reduced afterprecipitation events and then began to increase graduallyuntil the next event Small increases of salinity during majorrainfall intervals in Figure 5 may suggest that evaporationfails to accumulate salinity due to rainfall washout Thefluctuation in the groundwater salinity could be related toprecipitation events Part II showed the data curve from
November to December (dry season) wherein the amountof rainfall was lower than that during the wet seasonThe groundwater salinity showed increasing trends in earlyNovember and then sharply increased in late November Thegroundwater salinity increased with time and reached itsmaximum level (2445 gkg) in December
Table 1 shows that the groundwater salinity increasedas monthly precipitation decreased In July with abundantprecipitation the groundwater salinitywas only 087 gkg thelowest salinity level in the study time seriesThe groundwatersalinity increased each month until the maximum monthlyaverage was reached in December The groundwater salinityin December was approximately 23 times higher than that inJuly
Table 2 shows the 27 precipitation events that occurredduring the study series Changing percentage is a ratio whichis the differential value between groundwater salinity beforeand after rainfall divided by groundwater salinity beforerainfall The 1198772 value between precipitation and changingpercentage of groundwater salinity is 0653 which is signif-icant at the 001 level Precipitation influenced salt dilutionin groundwater A sufficient amount of rainfall diluted salt ingroundwater and decreased the groundwater salinity Inade-quate rainfall had no effect on decreasing the groundwatersalinity The highest rainfall of 744 cm did not cause ahigh percentage of change The highest change percentage ofgroundwater salinity was caused by a 603 cm precipitationevent and the 33 cm precipitation event the next day resultedin a 4522 change percentage The changing percentage wasrelated not only to rainfall but also to groundwater leveland the initial value of groundwater salinity The individualand small amount of rainfall had minimal or no effect ondecreasing the groundwater salinity particularly during thedry season Rainfalls were all less than 85 cm during the
Journal of Chemistry 5
200
100
0
0 10 20 30 40 50 60 70 80
Precipitation (cm)
Gro
undw
ater
fluc
tuat
ion
(cm
)
R2= 0833 P lt 001
minus10
(a)
Gro
undw
ater
fluc
tuat
ion
(cm
)
0
minus20
minus40
minus1 0 1 2 3 4 5 6 7 8
Evaporation (cm)
R2= 0235 P gt 005
(b)
0
minus100
minus200
150 200 250
River level (cm)
Gro
undw
ater
leve
l (cm
)
R2= 0346 P lt 001
(c)
0
minus100
minus200
Gro
undw
ater
leve
l (cm
)
minus50 0 50 100 150 200 250 300 350 400
Sea tide level (cm)
R2= 0004 P gt 005
(d)
Figure 4 Linear regressions among precipitation evaporation river stage sea tide level and groundwater level
Table 1 Monthly precipitation and evaporation and monthly average groundwater salinity and level seasonal precipitation and evaporationand average of groundwater salinity and level
Wet season Dry season Standard varianceJuly August September October November December
dry season and no rainfall recharged the groundwater inDecember groundwater salinity increasedThe groundwatersalinity sharply increased during the dry season when noprecipitation event occurred
33 Variations in Groundwater Salinity with GroundwaterLevel As analyzed in the preceding sections rainfall causedthe groundwater level and salinity to fluctuate and ground-water salinity was low when the amount of rainfall was
large After the decreasing of groundwater salinity causedby rainfall between two continuous precipitation eventsgroundwater salinity increased with the lowering of waterlevels Our findings suggest that salt movement is closelyrelated to the groundwater table
In different seasons the groundwater salinity exhibiteddifferent trends as the groundwater level changed as shownin Figure 6 Praveena et al indicated that high evaporationin areas with shallow groundwater tables may also lead to
6 Journal of Chemistry
Table 2 Changing percentage of groundwater salinity according to precipitation
Figure 5 Variations in groundwater salinity and precipitation fromJuly 1 to December 31 2013
salinization [7] During the wet season with high precip-itation and evaporation the groundwater level fluctuatedfrequently in a wide range and the groundwater salinityfluctuated synchronously with the groundwater level but thetrend appeared inversely
During the observation period the correlation coefficientbetween the groundwater level and salinity was 0324 andwas significantly correlated at the 001 level The correlationcoefficients from wet to dry seasons were 0259 and 0529respectively and both were significantly correlated at the 001level This finding suggested that the groundwater salinityis associated with the groundwater level The correlationcoefficient during the wet season was lower than that duringthe dry season Without the influence of precipitation events
a higher correlation between groundwater salinity and levelwas observed
From November to December the total rainfall wasonly 192 cm which occurred in early November Theseprecipitation events resulted in small groundwater levelfluctuations (Figure 6) The groundwater salinity curve didnot exhibit any noticeable fluctuation suggesting that thesmall amount of rainfall did not affect the groundwatersalinity After the precipitation events the groundwater tableremained relatively stable The groundwater level fluctuationinterval was 172 cm to 210 cm During this nonrainfall periodthe variations in groundwater salinity were not similar tothose at the groundwater level The groundwater salinityincreased suddenly in lateNovember before entering a periodof sustained and rapid growth Linear fits were conductedon groundwater salinity in early November and from lateNovember to December The linear fit equations were 119910 =0029119909 + 2649 and 119910 = 0528119909 + 3991 respectively Thegrowth rates of salinity were compared with the latter periodshowing higher levels than the former Without precipitationdilution shallow groundwater salinity increased continu-ously during the dry season
4 Discussion
The precipitation evaporation and groundwater level valuesare reported in Table 1 The time series shows that thewet season precipitation is significantly higher than thatduring the dry season accounting for 95 percent of totalprecipitation The evaporation and groundwater levels in thewet season are 5 times and 35 cm higher than those in the dryseason respectively
41 Effects of Precipitation River Stage and Evaporation onDynamics of Groundwater Level Thedynamics of groundwa-ter level in the study area are affectedmainly by precipitationwater level of nearby river and evaporation It was affected
Journal of Chemistry 7
25
20
15
10
5
0
Gro
undw
ater
salin
ity (g
kg)
0
50
100
150
200
250
Gro
undw
ater
leve
l (cm
)
Groundwater salinityGroundwater level
Data (ymd)
July
1 2
013
Augu
st 1
201
3
Sept
embe
r 1 2
013
Oct
ober
1 2
013
Nov
embe
r 1 2
013
Dec
embe
r 1 2
013
Figure 6 Variations in groundwater salinity with groundwater levelfluctuation
by precipitation evaporation and river stage Dogan et alApaydin Jan et al Hong and Wan and Carretero and Krusefound that precipitation was one of the dominant factors thatcontributed to groundwater level fluctuation [13 15ndash18] Inour study the groundwater levels quickly changed followingeach precipitation event After rainfall the groundwater levelpresented a linear downward trend because of evaporationuntil the next precipitation event occurred The groundwaterlevel was affected not only by precipitation and evaporationbut also by the river stage
42 Effects of Precipitation Dilution on Dynamics of Ground-water Salinity The groundwater salinity can be reduced afterthe recharge of precipitation events Research showed thatthe groundwater salinity changes according to precipita-tion events Wang et al pointed out that the precipitationinfiltrated and leached downward to recharge groundwaterwhich could refresh and dilute the salt of the soil wateror groundwater during the rainy season [6] Wang et alobserved that during dry seasons shallow groundwaterwould be sanitized because of the evaporation and conden-sation effects in the north China plain [6] Rabbani et alconfirmed that saline water starts to penetrate inland duringwinter months when river flow is low and groundwaterlevel decreases as a result of climate change in Bangladesh[12] These studies indicated that the shallow groundwatersalinity would increase by evaporation in the condition ofno precipitation or saline water penetrating In our studyhigh precipitation decreased the salinity concentration ingroundwater during the wet season and continues evapo-ration increase salinity dramatically during the dry seasonThe amount of precipitation serves an important function insalt dilution Taking advantage of precipitation can be a goodmethod to control groundwater salinity in a coastal plain
43 Variations in Groundwater Level Influence on Ground-water Salinity According to the entire study time seriesgroundwater salinity changed according to the fluctuationof groundwater level During the dry season the correlationcoefficient between the groundwater level and salinity washigher than that during the wet season The fluctuationsof groundwater level were mainly caused by precipitationand evaporation in wet season while in dry season thegroundwater level was mainly affected by the water level ofLiangduo River and groundwater salinity concentration wasincreased sharply by seawater intrusion Zhou et al foundthat the saltwater intrusion is mainly controlled by riverdischarge and tidal current in Zhujiang River Estuary [19] Itis also related to wind amplitude and direction and sea levelrising A deep mechanism of saltwater intrusion should beinvestigated For a clearer mechanism of saltwater intrusionin this study area not only climate factors but also moreinfluencing factors as above can be researched And spatialanalysis should be focused on
5 Conclusions
In coastal plain of eastern China the average depth ofgroundwater level is shallow and easily affected by climatefactors (precipitation and evaporation) and river stage Theinfluencing factors on the groundwater level were in theorder precipitation gt river stage gt evaporation The ground-water salinity is influenced by climate factors groundwaterlevel and seawater intrusion Precipitation infiltrated intogroundwater and diluted the salinity so the groundwatersalinity fluctuated with precipitation events Between twoprecipitation events groundwater salinity increased withevaporation Groundwater salinity changed with the fluctu-ation of groundwater level and significant correlation wasfound between them (119875 lt 001) In the study periodthe groundwater salinity fluctuated frequently During wetseason it maintained in a low salinity level It increasedcontinuously and reached a maximum value in Decemberduring the dry season The result indicated that seawaterintrusion occurred in the coastal plain in dry season
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
This study was financially supported by the Public WelfareIndustry Special Funds for Scientific Research Projects of theMinistry of Water Resources (Grant no 200801025) and theInnovative Project of Scientific Research for Postgraduatesin Ordinary Universities in Jiangsu Province (Grant noCXZZ13 0267) The authors thank Jiangsu Province Hydrol-ogy and Water Resources Investigation Bureau for providingthem with climate data
8 Journal of Chemistry
References
[1] P KumarM Tsujimura TNakano andTMinoru ldquoTime seriesanalysis for the estimation of tidal fluctuation effect on differentaquifers in a small coastal area of Saijo plain Ehime prefectureJapanrdquo Environmental Geochemistry and Health vol 35 no 2pp 239ndash250 2013
[2] M A T M T Rahman R K Majumder S H Rahmanand M A Halim ldquoSources of deep groundwater salinity inthe southwestern zone of Bangladeshrdquo Environmental EarthSciences vol 63 no 2 pp 363ndash373 2011
[3] Y Iwasaki M Ozaki K Nakamura H Horino and SKawashima ldquoRelationship between increment of groundwaterlevel at the beginning of irrigation period and paddy filed areain the Tedori River Alluvial Fan Area Japanrdquo Paddy and WaterEnvironment vol 11 no 1mdash4 pp 551ndash558 2013
[4] Z Chen S E Grasby and K G Osadetz ldquoRelation between cli-mate variability and groundwater levels in the upper carbonateaquifer southern Manitoba Canadardquo Journal of Hydrology vol290 no 1-2 pp 43ndash62 2004
[5] Z Chen S E Grasby and K G Osadetz ldquoPredicting averageannual groundwater levels from climatic variables an empiricalmodelrdquo Journal of Hydrology vol 260 no 1ndash4 pp 102ndash117 2002
[6] SWang X Song QWang et al ldquoShallow groundwater dynam-ics and origin of salinity at two sites in salinated and water-deficient region of North China Plain Chinardquo EnvironmentalEarth Sciences vol 66 no 3 pp 729ndash739 2012
[7] S M Praveena M H Abdullah K Bidin and A Z ArisldquoUnderstanding of groundwater salinity using statistical mod-eling in a small tropical island EastMalaysiardquo Environmentalistvol 31 no 3 pp 279ndash287 2011
[8] D Liu X Chen and Z Lou ldquoAmodel for the optimal allocationof water resources in a saltwater intrusion area a case study inpearl river delta in Chinardquo Water Resources Management vol24 no 1 pp 63ndash81 2010
[9] Z Li C Zhang and W Zhu ldquoThe present and analysis of thesea water intrusion in coastland of Rizhaordquo Hydrogeology andEngineering Geology vol 36 no 5 pp 129ndash132 2009 (Chinese)
[10] J G Redwood PumpRecharge Rate Affects Saltwater Intrusion2004 httpwwwsolinstcomresourcespapers101c4saltphp
[11] G H P Oude Essink ldquoSalt water intrusion in a three-dimensional groundwater system in the Netherlands a numer-ical studyrdquo Transport in Porous Media vol 43 no 1 pp 137ndash1582001
[12] G Rabbani A A Rahman and N Islam ldquoClimate change andsea level rise issues and challenges for coastal communitiesin the Indian Ocean Regionrdquo in Coastal Zones and ClimateChange D Michel and A Pandya Eds pp 17ndash30 The HenryL Stimson Center Washington DC USA 2010
[13] A Dogan H Demirpence and M Cobaner ldquoPrediction ofgroundwater levels from lake levels and climate data usingANNapproachrdquoWater SA vol 34 no 2 pp 199ndash208 2008
[14] Q Yong Z Zhang Y Fei et al ldquoCalculating precipitationrecharge to groundwater applying envieronmental chloridetracer methodrdquo in Proceedings of the International Symposiumon Water Resource and Environmental Protection (ISWREP rsquo11)vol 1 pp 139ndash143 Xirsquoan China May 2011
[15] A Apaydin ldquoResponse of groundwater to climate variationfluctuations of groundwater level and well yields in the Hala-cli aquifer (Cankiri Turkey)rdquo Environmental Monitoring andAssessment vol 165 no 1ndash4 pp 653ndash663 2010
[16] C-D Jan T-H Chen and H-M Huang ldquoAnalysis of rainfall-induced quick groundwater-level response by using a Kernelfunctionrdquo Paddy and Water Environment vol 11 no 1ndash4 pp135ndash144 2013
[17] Y-M Hong and S Wan ldquoForecasting groundwater level fluctu-ations for rainfall-induced landsliderdquo Natural Hazards vol 57no 2 pp 167ndash184 2011
[18] S C Carretero and E E Kruse ldquoRelationship between precip-itation and water-table fluctuation in a coastal dune aquiferNortheastern coast of the Buenos Aires province ArgentinardquoHydrogeology Journal vol 20 no 8 pp 1613ndash1621 2012
[19] W Zhou D Wang and L Luo ldquoInvestigation of saltwaterintrusion and salinity stratification in winter of 20072008 inthe Zhujiang River Estuary in ChinardquoActa Oceanologica Sinicavol 31 no 3 pp 31ndash46 2012
Figure 3 Groundwater fluctuation with precipitation and evaporation data from July 1 to December 31 2013
significant (119875 lt 001) effective on groundwater level in thestudy area The fitting curve showed positive correlationsamong groundwater level precipitation and river stage aswell as a negative correlation between groundwater leveland evaporation Estimating a dependent variable which isprecipitation largely contributed to obtaining groundwaterlevel with the highest 1198772 value The order of the influencingfactors on groundwater level was precipitation gt river stage gtevaporationThe sea tide level did not affect the groundwaterlevel (119875 gt 005)
The result indicates that precipitation mainly drivesdynamic changes in groundwater level in this study areaThe groundwater level exhibited multipeak curves and ashallower water level during the wet season than duringthe dry season because of frequent precipitation eventsDuring the dry season without rainfall the groundwater levelfluctuated because of fluctuations in the LiangduoRiver stageRiver stage had effect on groundwater level The tide level ofthe Yellow Sea had no influence on the groundwater level
32 Variations in Groundwater Salinity Groundwater salin-ity was generally affected by precipitation The statisticalvalues of precipitation and groundwater salinity are listed inTable 1 and the results are presented in Figure 5
The salinity data curve can be divided into two parts PartI showed the data curve from July to October (wet season)wherein the groundwater salinity fluctuated according to pre-cipitating events The groundwater salinity was reduced afterprecipitation events and then began to increase graduallyuntil the next event Small increases of salinity during majorrainfall intervals in Figure 5 may suggest that evaporationfails to accumulate salinity due to rainfall washout Thefluctuation in the groundwater salinity could be related toprecipitation events Part II showed the data curve from
November to December (dry season) wherein the amountof rainfall was lower than that during the wet seasonThe groundwater salinity showed increasing trends in earlyNovember and then sharply increased in late November Thegroundwater salinity increased with time and reached itsmaximum level (2445 gkg) in December
Table 1 shows that the groundwater salinity increasedas monthly precipitation decreased In July with abundantprecipitation the groundwater salinitywas only 087 gkg thelowest salinity level in the study time seriesThe groundwatersalinity increased each month until the maximum monthlyaverage was reached in December The groundwater salinityin December was approximately 23 times higher than that inJuly
Table 2 shows the 27 precipitation events that occurredduring the study series Changing percentage is a ratio whichis the differential value between groundwater salinity beforeand after rainfall divided by groundwater salinity beforerainfall The 1198772 value between precipitation and changingpercentage of groundwater salinity is 0653 which is signif-icant at the 001 level Precipitation influenced salt dilutionin groundwater A sufficient amount of rainfall diluted salt ingroundwater and decreased the groundwater salinity Inade-quate rainfall had no effect on decreasing the groundwatersalinity The highest rainfall of 744 cm did not cause ahigh percentage of change The highest change percentage ofgroundwater salinity was caused by a 603 cm precipitationevent and the 33 cm precipitation event the next day resultedin a 4522 change percentage The changing percentage wasrelated not only to rainfall but also to groundwater leveland the initial value of groundwater salinity The individualand small amount of rainfall had minimal or no effect ondecreasing the groundwater salinity particularly during thedry season Rainfalls were all less than 85 cm during the
Journal of Chemistry 5
200
100
0
0 10 20 30 40 50 60 70 80
Precipitation (cm)
Gro
undw
ater
fluc
tuat
ion
(cm
)
R2= 0833 P lt 001
minus10
(a)
Gro
undw
ater
fluc
tuat
ion
(cm
)
0
minus20
minus40
minus1 0 1 2 3 4 5 6 7 8
Evaporation (cm)
R2= 0235 P gt 005
(b)
0
minus100
minus200
150 200 250
River level (cm)
Gro
undw
ater
leve
l (cm
)
R2= 0346 P lt 001
(c)
0
minus100
minus200
Gro
undw
ater
leve
l (cm
)
minus50 0 50 100 150 200 250 300 350 400
Sea tide level (cm)
R2= 0004 P gt 005
(d)
Figure 4 Linear regressions among precipitation evaporation river stage sea tide level and groundwater level
Table 1 Monthly precipitation and evaporation and monthly average groundwater salinity and level seasonal precipitation and evaporationand average of groundwater salinity and level
Wet season Dry season Standard varianceJuly August September October November December
dry season and no rainfall recharged the groundwater inDecember groundwater salinity increasedThe groundwatersalinity sharply increased during the dry season when noprecipitation event occurred
33 Variations in Groundwater Salinity with GroundwaterLevel As analyzed in the preceding sections rainfall causedthe groundwater level and salinity to fluctuate and ground-water salinity was low when the amount of rainfall was
large After the decreasing of groundwater salinity causedby rainfall between two continuous precipitation eventsgroundwater salinity increased with the lowering of waterlevels Our findings suggest that salt movement is closelyrelated to the groundwater table
In different seasons the groundwater salinity exhibiteddifferent trends as the groundwater level changed as shownin Figure 6 Praveena et al indicated that high evaporationin areas with shallow groundwater tables may also lead to
6 Journal of Chemistry
Table 2 Changing percentage of groundwater salinity according to precipitation
Figure 5 Variations in groundwater salinity and precipitation fromJuly 1 to December 31 2013
salinization [7] During the wet season with high precip-itation and evaporation the groundwater level fluctuatedfrequently in a wide range and the groundwater salinityfluctuated synchronously with the groundwater level but thetrend appeared inversely
During the observation period the correlation coefficientbetween the groundwater level and salinity was 0324 andwas significantly correlated at the 001 level The correlationcoefficients from wet to dry seasons were 0259 and 0529respectively and both were significantly correlated at the 001level This finding suggested that the groundwater salinityis associated with the groundwater level The correlationcoefficient during the wet season was lower than that duringthe dry season Without the influence of precipitation events
a higher correlation between groundwater salinity and levelwas observed
From November to December the total rainfall wasonly 192 cm which occurred in early November Theseprecipitation events resulted in small groundwater levelfluctuations (Figure 6) The groundwater salinity curve didnot exhibit any noticeable fluctuation suggesting that thesmall amount of rainfall did not affect the groundwatersalinity After the precipitation events the groundwater tableremained relatively stable The groundwater level fluctuationinterval was 172 cm to 210 cm During this nonrainfall periodthe variations in groundwater salinity were not similar tothose at the groundwater level The groundwater salinityincreased suddenly in lateNovember before entering a periodof sustained and rapid growth Linear fits were conductedon groundwater salinity in early November and from lateNovember to December The linear fit equations were 119910 =0029119909 + 2649 and 119910 = 0528119909 + 3991 respectively Thegrowth rates of salinity were compared with the latter periodshowing higher levels than the former Without precipitationdilution shallow groundwater salinity increased continu-ously during the dry season
4 Discussion
The precipitation evaporation and groundwater level valuesare reported in Table 1 The time series shows that thewet season precipitation is significantly higher than thatduring the dry season accounting for 95 percent of totalprecipitation The evaporation and groundwater levels in thewet season are 5 times and 35 cm higher than those in the dryseason respectively
41 Effects of Precipitation River Stage and Evaporation onDynamics of Groundwater Level Thedynamics of groundwa-ter level in the study area are affectedmainly by precipitationwater level of nearby river and evaporation It was affected
Journal of Chemistry 7
25
20
15
10
5
0
Gro
undw
ater
salin
ity (g
kg)
0
50
100
150
200
250
Gro
undw
ater
leve
l (cm
)
Groundwater salinityGroundwater level
Data (ymd)
July
1 2
013
Augu
st 1
201
3
Sept
embe
r 1 2
013
Oct
ober
1 2
013
Nov
embe
r 1 2
013
Dec
embe
r 1 2
013
Figure 6 Variations in groundwater salinity with groundwater levelfluctuation
by precipitation evaporation and river stage Dogan et alApaydin Jan et al Hong and Wan and Carretero and Krusefound that precipitation was one of the dominant factors thatcontributed to groundwater level fluctuation [13 15ndash18] Inour study the groundwater levels quickly changed followingeach precipitation event After rainfall the groundwater levelpresented a linear downward trend because of evaporationuntil the next precipitation event occurred The groundwaterlevel was affected not only by precipitation and evaporationbut also by the river stage
42 Effects of Precipitation Dilution on Dynamics of Ground-water Salinity The groundwater salinity can be reduced afterthe recharge of precipitation events Research showed thatthe groundwater salinity changes according to precipita-tion events Wang et al pointed out that the precipitationinfiltrated and leached downward to recharge groundwaterwhich could refresh and dilute the salt of the soil wateror groundwater during the rainy season [6] Wang et alobserved that during dry seasons shallow groundwaterwould be sanitized because of the evaporation and conden-sation effects in the north China plain [6] Rabbani et alconfirmed that saline water starts to penetrate inland duringwinter months when river flow is low and groundwaterlevel decreases as a result of climate change in Bangladesh[12] These studies indicated that the shallow groundwatersalinity would increase by evaporation in the condition ofno precipitation or saline water penetrating In our studyhigh precipitation decreased the salinity concentration ingroundwater during the wet season and continues evapo-ration increase salinity dramatically during the dry seasonThe amount of precipitation serves an important function insalt dilution Taking advantage of precipitation can be a goodmethod to control groundwater salinity in a coastal plain
43 Variations in Groundwater Level Influence on Ground-water Salinity According to the entire study time seriesgroundwater salinity changed according to the fluctuationof groundwater level During the dry season the correlationcoefficient between the groundwater level and salinity washigher than that during the wet season The fluctuationsof groundwater level were mainly caused by precipitationand evaporation in wet season while in dry season thegroundwater level was mainly affected by the water level ofLiangduo River and groundwater salinity concentration wasincreased sharply by seawater intrusion Zhou et al foundthat the saltwater intrusion is mainly controlled by riverdischarge and tidal current in Zhujiang River Estuary [19] Itis also related to wind amplitude and direction and sea levelrising A deep mechanism of saltwater intrusion should beinvestigated For a clearer mechanism of saltwater intrusionin this study area not only climate factors but also moreinfluencing factors as above can be researched And spatialanalysis should be focused on
5 Conclusions
In coastal plain of eastern China the average depth ofgroundwater level is shallow and easily affected by climatefactors (precipitation and evaporation) and river stage Theinfluencing factors on the groundwater level were in theorder precipitation gt river stage gt evaporation The ground-water salinity is influenced by climate factors groundwaterlevel and seawater intrusion Precipitation infiltrated intogroundwater and diluted the salinity so the groundwatersalinity fluctuated with precipitation events Between twoprecipitation events groundwater salinity increased withevaporation Groundwater salinity changed with the fluctu-ation of groundwater level and significant correlation wasfound between them (119875 lt 001) In the study periodthe groundwater salinity fluctuated frequently During wetseason it maintained in a low salinity level It increasedcontinuously and reached a maximum value in Decemberduring the dry season The result indicated that seawaterintrusion occurred in the coastal plain in dry season
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
This study was financially supported by the Public WelfareIndustry Special Funds for Scientific Research Projects of theMinistry of Water Resources (Grant no 200801025) and theInnovative Project of Scientific Research for Postgraduatesin Ordinary Universities in Jiangsu Province (Grant noCXZZ13 0267) The authors thank Jiangsu Province Hydrol-ogy and Water Resources Investigation Bureau for providingthem with climate data
8 Journal of Chemistry
References
[1] P KumarM Tsujimura TNakano andTMinoru ldquoTime seriesanalysis for the estimation of tidal fluctuation effect on differentaquifers in a small coastal area of Saijo plain Ehime prefectureJapanrdquo Environmental Geochemistry and Health vol 35 no 2pp 239ndash250 2013
[2] M A T M T Rahman R K Majumder S H Rahmanand M A Halim ldquoSources of deep groundwater salinity inthe southwestern zone of Bangladeshrdquo Environmental EarthSciences vol 63 no 2 pp 363ndash373 2011
[3] Y Iwasaki M Ozaki K Nakamura H Horino and SKawashima ldquoRelationship between increment of groundwaterlevel at the beginning of irrigation period and paddy filed areain the Tedori River Alluvial Fan Area Japanrdquo Paddy and WaterEnvironment vol 11 no 1mdash4 pp 551ndash558 2013
[4] Z Chen S E Grasby and K G Osadetz ldquoRelation between cli-mate variability and groundwater levels in the upper carbonateaquifer southern Manitoba Canadardquo Journal of Hydrology vol290 no 1-2 pp 43ndash62 2004
[5] Z Chen S E Grasby and K G Osadetz ldquoPredicting averageannual groundwater levels from climatic variables an empiricalmodelrdquo Journal of Hydrology vol 260 no 1ndash4 pp 102ndash117 2002
[6] SWang X Song QWang et al ldquoShallow groundwater dynam-ics and origin of salinity at two sites in salinated and water-deficient region of North China Plain Chinardquo EnvironmentalEarth Sciences vol 66 no 3 pp 729ndash739 2012
[7] S M Praveena M H Abdullah K Bidin and A Z ArisldquoUnderstanding of groundwater salinity using statistical mod-eling in a small tropical island EastMalaysiardquo Environmentalistvol 31 no 3 pp 279ndash287 2011
[8] D Liu X Chen and Z Lou ldquoAmodel for the optimal allocationof water resources in a saltwater intrusion area a case study inpearl river delta in Chinardquo Water Resources Management vol24 no 1 pp 63ndash81 2010
[9] Z Li C Zhang and W Zhu ldquoThe present and analysis of thesea water intrusion in coastland of Rizhaordquo Hydrogeology andEngineering Geology vol 36 no 5 pp 129ndash132 2009 (Chinese)
[10] J G Redwood PumpRecharge Rate Affects Saltwater Intrusion2004 httpwwwsolinstcomresourcespapers101c4saltphp
[11] G H P Oude Essink ldquoSalt water intrusion in a three-dimensional groundwater system in the Netherlands a numer-ical studyrdquo Transport in Porous Media vol 43 no 1 pp 137ndash1582001
[12] G Rabbani A A Rahman and N Islam ldquoClimate change andsea level rise issues and challenges for coastal communitiesin the Indian Ocean Regionrdquo in Coastal Zones and ClimateChange D Michel and A Pandya Eds pp 17ndash30 The HenryL Stimson Center Washington DC USA 2010
[13] A Dogan H Demirpence and M Cobaner ldquoPrediction ofgroundwater levels from lake levels and climate data usingANNapproachrdquoWater SA vol 34 no 2 pp 199ndash208 2008
[14] Q Yong Z Zhang Y Fei et al ldquoCalculating precipitationrecharge to groundwater applying envieronmental chloridetracer methodrdquo in Proceedings of the International Symposiumon Water Resource and Environmental Protection (ISWREP rsquo11)vol 1 pp 139ndash143 Xirsquoan China May 2011
[15] A Apaydin ldquoResponse of groundwater to climate variationfluctuations of groundwater level and well yields in the Hala-cli aquifer (Cankiri Turkey)rdquo Environmental Monitoring andAssessment vol 165 no 1ndash4 pp 653ndash663 2010
[16] C-D Jan T-H Chen and H-M Huang ldquoAnalysis of rainfall-induced quick groundwater-level response by using a Kernelfunctionrdquo Paddy and Water Environment vol 11 no 1ndash4 pp135ndash144 2013
[17] Y-M Hong and S Wan ldquoForecasting groundwater level fluctu-ations for rainfall-induced landsliderdquo Natural Hazards vol 57no 2 pp 167ndash184 2011
[18] S C Carretero and E E Kruse ldquoRelationship between precip-itation and water-table fluctuation in a coastal dune aquiferNortheastern coast of the Buenos Aires province ArgentinardquoHydrogeology Journal vol 20 no 8 pp 1613ndash1621 2012
[19] W Zhou D Wang and L Luo ldquoInvestigation of saltwaterintrusion and salinity stratification in winter of 20072008 inthe Zhujiang River Estuary in ChinardquoActa Oceanologica Sinicavol 31 no 3 pp 31ndash46 2012
Figure 4 Linear regressions among precipitation evaporation river stage sea tide level and groundwater level
Table 1 Monthly precipitation and evaporation and monthly average groundwater salinity and level seasonal precipitation and evaporationand average of groundwater salinity and level
Wet season Dry season Standard varianceJuly August September October November December
dry season and no rainfall recharged the groundwater inDecember groundwater salinity increasedThe groundwatersalinity sharply increased during the dry season when noprecipitation event occurred
33 Variations in Groundwater Salinity with GroundwaterLevel As analyzed in the preceding sections rainfall causedthe groundwater level and salinity to fluctuate and ground-water salinity was low when the amount of rainfall was
large After the decreasing of groundwater salinity causedby rainfall between two continuous precipitation eventsgroundwater salinity increased with the lowering of waterlevels Our findings suggest that salt movement is closelyrelated to the groundwater table
In different seasons the groundwater salinity exhibiteddifferent trends as the groundwater level changed as shownin Figure 6 Praveena et al indicated that high evaporationin areas with shallow groundwater tables may also lead to
6 Journal of Chemistry
Table 2 Changing percentage of groundwater salinity according to precipitation
Figure 5 Variations in groundwater salinity and precipitation fromJuly 1 to December 31 2013
salinization [7] During the wet season with high precip-itation and evaporation the groundwater level fluctuatedfrequently in a wide range and the groundwater salinityfluctuated synchronously with the groundwater level but thetrend appeared inversely
During the observation period the correlation coefficientbetween the groundwater level and salinity was 0324 andwas significantly correlated at the 001 level The correlationcoefficients from wet to dry seasons were 0259 and 0529respectively and both were significantly correlated at the 001level This finding suggested that the groundwater salinityis associated with the groundwater level The correlationcoefficient during the wet season was lower than that duringthe dry season Without the influence of precipitation events
a higher correlation between groundwater salinity and levelwas observed
From November to December the total rainfall wasonly 192 cm which occurred in early November Theseprecipitation events resulted in small groundwater levelfluctuations (Figure 6) The groundwater salinity curve didnot exhibit any noticeable fluctuation suggesting that thesmall amount of rainfall did not affect the groundwatersalinity After the precipitation events the groundwater tableremained relatively stable The groundwater level fluctuationinterval was 172 cm to 210 cm During this nonrainfall periodthe variations in groundwater salinity were not similar tothose at the groundwater level The groundwater salinityincreased suddenly in lateNovember before entering a periodof sustained and rapid growth Linear fits were conductedon groundwater salinity in early November and from lateNovember to December The linear fit equations were 119910 =0029119909 + 2649 and 119910 = 0528119909 + 3991 respectively Thegrowth rates of salinity were compared with the latter periodshowing higher levels than the former Without precipitationdilution shallow groundwater salinity increased continu-ously during the dry season
4 Discussion
The precipitation evaporation and groundwater level valuesare reported in Table 1 The time series shows that thewet season precipitation is significantly higher than thatduring the dry season accounting for 95 percent of totalprecipitation The evaporation and groundwater levels in thewet season are 5 times and 35 cm higher than those in the dryseason respectively
41 Effects of Precipitation River Stage and Evaporation onDynamics of Groundwater Level Thedynamics of groundwa-ter level in the study area are affectedmainly by precipitationwater level of nearby river and evaporation It was affected
Journal of Chemistry 7
25
20
15
10
5
0
Gro
undw
ater
salin
ity (g
kg)
0
50
100
150
200
250
Gro
undw
ater
leve
l (cm
)
Groundwater salinityGroundwater level
Data (ymd)
July
1 2
013
Augu
st 1
201
3
Sept
embe
r 1 2
013
Oct
ober
1 2
013
Nov
embe
r 1 2
013
Dec
embe
r 1 2
013
Figure 6 Variations in groundwater salinity with groundwater levelfluctuation
by precipitation evaporation and river stage Dogan et alApaydin Jan et al Hong and Wan and Carretero and Krusefound that precipitation was one of the dominant factors thatcontributed to groundwater level fluctuation [13 15ndash18] Inour study the groundwater levels quickly changed followingeach precipitation event After rainfall the groundwater levelpresented a linear downward trend because of evaporationuntil the next precipitation event occurred The groundwaterlevel was affected not only by precipitation and evaporationbut also by the river stage
42 Effects of Precipitation Dilution on Dynamics of Ground-water Salinity The groundwater salinity can be reduced afterthe recharge of precipitation events Research showed thatthe groundwater salinity changes according to precipita-tion events Wang et al pointed out that the precipitationinfiltrated and leached downward to recharge groundwaterwhich could refresh and dilute the salt of the soil wateror groundwater during the rainy season [6] Wang et alobserved that during dry seasons shallow groundwaterwould be sanitized because of the evaporation and conden-sation effects in the north China plain [6] Rabbani et alconfirmed that saline water starts to penetrate inland duringwinter months when river flow is low and groundwaterlevel decreases as a result of climate change in Bangladesh[12] These studies indicated that the shallow groundwatersalinity would increase by evaporation in the condition ofno precipitation or saline water penetrating In our studyhigh precipitation decreased the salinity concentration ingroundwater during the wet season and continues evapo-ration increase salinity dramatically during the dry seasonThe amount of precipitation serves an important function insalt dilution Taking advantage of precipitation can be a goodmethod to control groundwater salinity in a coastal plain
43 Variations in Groundwater Level Influence on Ground-water Salinity According to the entire study time seriesgroundwater salinity changed according to the fluctuationof groundwater level During the dry season the correlationcoefficient between the groundwater level and salinity washigher than that during the wet season The fluctuationsof groundwater level were mainly caused by precipitationand evaporation in wet season while in dry season thegroundwater level was mainly affected by the water level ofLiangduo River and groundwater salinity concentration wasincreased sharply by seawater intrusion Zhou et al foundthat the saltwater intrusion is mainly controlled by riverdischarge and tidal current in Zhujiang River Estuary [19] Itis also related to wind amplitude and direction and sea levelrising A deep mechanism of saltwater intrusion should beinvestigated For a clearer mechanism of saltwater intrusionin this study area not only climate factors but also moreinfluencing factors as above can be researched And spatialanalysis should be focused on
5 Conclusions
In coastal plain of eastern China the average depth ofgroundwater level is shallow and easily affected by climatefactors (precipitation and evaporation) and river stage Theinfluencing factors on the groundwater level were in theorder precipitation gt river stage gt evaporation The ground-water salinity is influenced by climate factors groundwaterlevel and seawater intrusion Precipitation infiltrated intogroundwater and diluted the salinity so the groundwatersalinity fluctuated with precipitation events Between twoprecipitation events groundwater salinity increased withevaporation Groundwater salinity changed with the fluctu-ation of groundwater level and significant correlation wasfound between them (119875 lt 001) In the study periodthe groundwater salinity fluctuated frequently During wetseason it maintained in a low salinity level It increasedcontinuously and reached a maximum value in Decemberduring the dry season The result indicated that seawaterintrusion occurred in the coastal plain in dry season
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
This study was financially supported by the Public WelfareIndustry Special Funds for Scientific Research Projects of theMinistry of Water Resources (Grant no 200801025) and theInnovative Project of Scientific Research for Postgraduatesin Ordinary Universities in Jiangsu Province (Grant noCXZZ13 0267) The authors thank Jiangsu Province Hydrol-ogy and Water Resources Investigation Bureau for providingthem with climate data
8 Journal of Chemistry
References
[1] P KumarM Tsujimura TNakano andTMinoru ldquoTime seriesanalysis for the estimation of tidal fluctuation effect on differentaquifers in a small coastal area of Saijo plain Ehime prefectureJapanrdquo Environmental Geochemistry and Health vol 35 no 2pp 239ndash250 2013
[2] M A T M T Rahman R K Majumder S H Rahmanand M A Halim ldquoSources of deep groundwater salinity inthe southwestern zone of Bangladeshrdquo Environmental EarthSciences vol 63 no 2 pp 363ndash373 2011
[3] Y Iwasaki M Ozaki K Nakamura H Horino and SKawashima ldquoRelationship between increment of groundwaterlevel at the beginning of irrigation period and paddy filed areain the Tedori River Alluvial Fan Area Japanrdquo Paddy and WaterEnvironment vol 11 no 1mdash4 pp 551ndash558 2013
[4] Z Chen S E Grasby and K G Osadetz ldquoRelation between cli-mate variability and groundwater levels in the upper carbonateaquifer southern Manitoba Canadardquo Journal of Hydrology vol290 no 1-2 pp 43ndash62 2004
[5] Z Chen S E Grasby and K G Osadetz ldquoPredicting averageannual groundwater levels from climatic variables an empiricalmodelrdquo Journal of Hydrology vol 260 no 1ndash4 pp 102ndash117 2002
[6] SWang X Song QWang et al ldquoShallow groundwater dynam-ics and origin of salinity at two sites in salinated and water-deficient region of North China Plain Chinardquo EnvironmentalEarth Sciences vol 66 no 3 pp 729ndash739 2012
[7] S M Praveena M H Abdullah K Bidin and A Z ArisldquoUnderstanding of groundwater salinity using statistical mod-eling in a small tropical island EastMalaysiardquo Environmentalistvol 31 no 3 pp 279ndash287 2011
[8] D Liu X Chen and Z Lou ldquoAmodel for the optimal allocationof water resources in a saltwater intrusion area a case study inpearl river delta in Chinardquo Water Resources Management vol24 no 1 pp 63ndash81 2010
[9] Z Li C Zhang and W Zhu ldquoThe present and analysis of thesea water intrusion in coastland of Rizhaordquo Hydrogeology andEngineering Geology vol 36 no 5 pp 129ndash132 2009 (Chinese)
[10] J G Redwood PumpRecharge Rate Affects Saltwater Intrusion2004 httpwwwsolinstcomresourcespapers101c4saltphp
[11] G H P Oude Essink ldquoSalt water intrusion in a three-dimensional groundwater system in the Netherlands a numer-ical studyrdquo Transport in Porous Media vol 43 no 1 pp 137ndash1582001
[12] G Rabbani A A Rahman and N Islam ldquoClimate change andsea level rise issues and challenges for coastal communitiesin the Indian Ocean Regionrdquo in Coastal Zones and ClimateChange D Michel and A Pandya Eds pp 17ndash30 The HenryL Stimson Center Washington DC USA 2010
[13] A Dogan H Demirpence and M Cobaner ldquoPrediction ofgroundwater levels from lake levels and climate data usingANNapproachrdquoWater SA vol 34 no 2 pp 199ndash208 2008
[14] Q Yong Z Zhang Y Fei et al ldquoCalculating precipitationrecharge to groundwater applying envieronmental chloridetracer methodrdquo in Proceedings of the International Symposiumon Water Resource and Environmental Protection (ISWREP rsquo11)vol 1 pp 139ndash143 Xirsquoan China May 2011
[15] A Apaydin ldquoResponse of groundwater to climate variationfluctuations of groundwater level and well yields in the Hala-cli aquifer (Cankiri Turkey)rdquo Environmental Monitoring andAssessment vol 165 no 1ndash4 pp 653ndash663 2010
[16] C-D Jan T-H Chen and H-M Huang ldquoAnalysis of rainfall-induced quick groundwater-level response by using a Kernelfunctionrdquo Paddy and Water Environment vol 11 no 1ndash4 pp135ndash144 2013
[17] Y-M Hong and S Wan ldquoForecasting groundwater level fluctu-ations for rainfall-induced landsliderdquo Natural Hazards vol 57no 2 pp 167ndash184 2011
[18] S C Carretero and E E Kruse ldquoRelationship between precip-itation and water-table fluctuation in a coastal dune aquiferNortheastern coast of the Buenos Aires province ArgentinardquoHydrogeology Journal vol 20 no 8 pp 1613ndash1621 2012
[19] W Zhou D Wang and L Luo ldquoInvestigation of saltwaterintrusion and salinity stratification in winter of 20072008 inthe Zhujiang River Estuary in ChinardquoActa Oceanologica Sinicavol 31 no 3 pp 31ndash46 2012
Figure 5 Variations in groundwater salinity and precipitation fromJuly 1 to December 31 2013
salinization [7] During the wet season with high precip-itation and evaporation the groundwater level fluctuatedfrequently in a wide range and the groundwater salinityfluctuated synchronously with the groundwater level but thetrend appeared inversely
During the observation period the correlation coefficientbetween the groundwater level and salinity was 0324 andwas significantly correlated at the 001 level The correlationcoefficients from wet to dry seasons were 0259 and 0529respectively and both were significantly correlated at the 001level This finding suggested that the groundwater salinityis associated with the groundwater level The correlationcoefficient during the wet season was lower than that duringthe dry season Without the influence of precipitation events
a higher correlation between groundwater salinity and levelwas observed
From November to December the total rainfall wasonly 192 cm which occurred in early November Theseprecipitation events resulted in small groundwater levelfluctuations (Figure 6) The groundwater salinity curve didnot exhibit any noticeable fluctuation suggesting that thesmall amount of rainfall did not affect the groundwatersalinity After the precipitation events the groundwater tableremained relatively stable The groundwater level fluctuationinterval was 172 cm to 210 cm During this nonrainfall periodthe variations in groundwater salinity were not similar tothose at the groundwater level The groundwater salinityincreased suddenly in lateNovember before entering a periodof sustained and rapid growth Linear fits were conductedon groundwater salinity in early November and from lateNovember to December The linear fit equations were 119910 =0029119909 + 2649 and 119910 = 0528119909 + 3991 respectively Thegrowth rates of salinity were compared with the latter periodshowing higher levels than the former Without precipitationdilution shallow groundwater salinity increased continu-ously during the dry season
4 Discussion
The precipitation evaporation and groundwater level valuesare reported in Table 1 The time series shows that thewet season precipitation is significantly higher than thatduring the dry season accounting for 95 percent of totalprecipitation The evaporation and groundwater levels in thewet season are 5 times and 35 cm higher than those in the dryseason respectively
41 Effects of Precipitation River Stage and Evaporation onDynamics of Groundwater Level Thedynamics of groundwa-ter level in the study area are affectedmainly by precipitationwater level of nearby river and evaporation It was affected
Journal of Chemistry 7
25
20
15
10
5
0
Gro
undw
ater
salin
ity (g
kg)
0
50
100
150
200
250
Gro
undw
ater
leve
l (cm
)
Groundwater salinityGroundwater level
Data (ymd)
July
1 2
013
Augu
st 1
201
3
Sept
embe
r 1 2
013
Oct
ober
1 2
013
Nov
embe
r 1 2
013
Dec
embe
r 1 2
013
Figure 6 Variations in groundwater salinity with groundwater levelfluctuation
by precipitation evaporation and river stage Dogan et alApaydin Jan et al Hong and Wan and Carretero and Krusefound that precipitation was one of the dominant factors thatcontributed to groundwater level fluctuation [13 15ndash18] Inour study the groundwater levels quickly changed followingeach precipitation event After rainfall the groundwater levelpresented a linear downward trend because of evaporationuntil the next precipitation event occurred The groundwaterlevel was affected not only by precipitation and evaporationbut also by the river stage
42 Effects of Precipitation Dilution on Dynamics of Ground-water Salinity The groundwater salinity can be reduced afterthe recharge of precipitation events Research showed thatthe groundwater salinity changes according to precipita-tion events Wang et al pointed out that the precipitationinfiltrated and leached downward to recharge groundwaterwhich could refresh and dilute the salt of the soil wateror groundwater during the rainy season [6] Wang et alobserved that during dry seasons shallow groundwaterwould be sanitized because of the evaporation and conden-sation effects in the north China plain [6] Rabbani et alconfirmed that saline water starts to penetrate inland duringwinter months when river flow is low and groundwaterlevel decreases as a result of climate change in Bangladesh[12] These studies indicated that the shallow groundwatersalinity would increase by evaporation in the condition ofno precipitation or saline water penetrating In our studyhigh precipitation decreased the salinity concentration ingroundwater during the wet season and continues evapo-ration increase salinity dramatically during the dry seasonThe amount of precipitation serves an important function insalt dilution Taking advantage of precipitation can be a goodmethod to control groundwater salinity in a coastal plain
43 Variations in Groundwater Level Influence on Ground-water Salinity According to the entire study time seriesgroundwater salinity changed according to the fluctuationof groundwater level During the dry season the correlationcoefficient between the groundwater level and salinity washigher than that during the wet season The fluctuationsof groundwater level were mainly caused by precipitationand evaporation in wet season while in dry season thegroundwater level was mainly affected by the water level ofLiangduo River and groundwater salinity concentration wasincreased sharply by seawater intrusion Zhou et al foundthat the saltwater intrusion is mainly controlled by riverdischarge and tidal current in Zhujiang River Estuary [19] Itis also related to wind amplitude and direction and sea levelrising A deep mechanism of saltwater intrusion should beinvestigated For a clearer mechanism of saltwater intrusionin this study area not only climate factors but also moreinfluencing factors as above can be researched And spatialanalysis should be focused on
5 Conclusions
In coastal plain of eastern China the average depth ofgroundwater level is shallow and easily affected by climatefactors (precipitation and evaporation) and river stage Theinfluencing factors on the groundwater level were in theorder precipitation gt river stage gt evaporation The ground-water salinity is influenced by climate factors groundwaterlevel and seawater intrusion Precipitation infiltrated intogroundwater and diluted the salinity so the groundwatersalinity fluctuated with precipitation events Between twoprecipitation events groundwater salinity increased withevaporation Groundwater salinity changed with the fluctu-ation of groundwater level and significant correlation wasfound between them (119875 lt 001) In the study periodthe groundwater salinity fluctuated frequently During wetseason it maintained in a low salinity level It increasedcontinuously and reached a maximum value in Decemberduring the dry season The result indicated that seawaterintrusion occurred in the coastal plain in dry season
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
This study was financially supported by the Public WelfareIndustry Special Funds for Scientific Research Projects of theMinistry of Water Resources (Grant no 200801025) and theInnovative Project of Scientific Research for Postgraduatesin Ordinary Universities in Jiangsu Province (Grant noCXZZ13 0267) The authors thank Jiangsu Province Hydrol-ogy and Water Resources Investigation Bureau for providingthem with climate data
8 Journal of Chemistry
References
[1] P KumarM Tsujimura TNakano andTMinoru ldquoTime seriesanalysis for the estimation of tidal fluctuation effect on differentaquifers in a small coastal area of Saijo plain Ehime prefectureJapanrdquo Environmental Geochemistry and Health vol 35 no 2pp 239ndash250 2013
[2] M A T M T Rahman R K Majumder S H Rahmanand M A Halim ldquoSources of deep groundwater salinity inthe southwestern zone of Bangladeshrdquo Environmental EarthSciences vol 63 no 2 pp 363ndash373 2011
[3] Y Iwasaki M Ozaki K Nakamura H Horino and SKawashima ldquoRelationship between increment of groundwaterlevel at the beginning of irrigation period and paddy filed areain the Tedori River Alluvial Fan Area Japanrdquo Paddy and WaterEnvironment vol 11 no 1mdash4 pp 551ndash558 2013
[4] Z Chen S E Grasby and K G Osadetz ldquoRelation between cli-mate variability and groundwater levels in the upper carbonateaquifer southern Manitoba Canadardquo Journal of Hydrology vol290 no 1-2 pp 43ndash62 2004
[5] Z Chen S E Grasby and K G Osadetz ldquoPredicting averageannual groundwater levels from climatic variables an empiricalmodelrdquo Journal of Hydrology vol 260 no 1ndash4 pp 102ndash117 2002
[6] SWang X Song QWang et al ldquoShallow groundwater dynam-ics and origin of salinity at two sites in salinated and water-deficient region of North China Plain Chinardquo EnvironmentalEarth Sciences vol 66 no 3 pp 729ndash739 2012
[7] S M Praveena M H Abdullah K Bidin and A Z ArisldquoUnderstanding of groundwater salinity using statistical mod-eling in a small tropical island EastMalaysiardquo Environmentalistvol 31 no 3 pp 279ndash287 2011
[8] D Liu X Chen and Z Lou ldquoAmodel for the optimal allocationof water resources in a saltwater intrusion area a case study inpearl river delta in Chinardquo Water Resources Management vol24 no 1 pp 63ndash81 2010
[9] Z Li C Zhang and W Zhu ldquoThe present and analysis of thesea water intrusion in coastland of Rizhaordquo Hydrogeology andEngineering Geology vol 36 no 5 pp 129ndash132 2009 (Chinese)
[10] J G Redwood PumpRecharge Rate Affects Saltwater Intrusion2004 httpwwwsolinstcomresourcespapers101c4saltphp
[11] G H P Oude Essink ldquoSalt water intrusion in a three-dimensional groundwater system in the Netherlands a numer-ical studyrdquo Transport in Porous Media vol 43 no 1 pp 137ndash1582001
[12] G Rabbani A A Rahman and N Islam ldquoClimate change andsea level rise issues and challenges for coastal communitiesin the Indian Ocean Regionrdquo in Coastal Zones and ClimateChange D Michel and A Pandya Eds pp 17ndash30 The HenryL Stimson Center Washington DC USA 2010
[13] A Dogan H Demirpence and M Cobaner ldquoPrediction ofgroundwater levels from lake levels and climate data usingANNapproachrdquoWater SA vol 34 no 2 pp 199ndash208 2008
[14] Q Yong Z Zhang Y Fei et al ldquoCalculating precipitationrecharge to groundwater applying envieronmental chloridetracer methodrdquo in Proceedings of the International Symposiumon Water Resource and Environmental Protection (ISWREP rsquo11)vol 1 pp 139ndash143 Xirsquoan China May 2011
[15] A Apaydin ldquoResponse of groundwater to climate variationfluctuations of groundwater level and well yields in the Hala-cli aquifer (Cankiri Turkey)rdquo Environmental Monitoring andAssessment vol 165 no 1ndash4 pp 653ndash663 2010
[16] C-D Jan T-H Chen and H-M Huang ldquoAnalysis of rainfall-induced quick groundwater-level response by using a Kernelfunctionrdquo Paddy and Water Environment vol 11 no 1ndash4 pp135ndash144 2013
[17] Y-M Hong and S Wan ldquoForecasting groundwater level fluctu-ations for rainfall-induced landsliderdquo Natural Hazards vol 57no 2 pp 167ndash184 2011
[18] S C Carretero and E E Kruse ldquoRelationship between precip-itation and water-table fluctuation in a coastal dune aquiferNortheastern coast of the Buenos Aires province ArgentinardquoHydrogeology Journal vol 20 no 8 pp 1613ndash1621 2012
[19] W Zhou D Wang and L Luo ldquoInvestigation of saltwaterintrusion and salinity stratification in winter of 20072008 inthe Zhujiang River Estuary in ChinardquoActa Oceanologica Sinicavol 31 no 3 pp 31ndash46 2012
Figure 6 Variations in groundwater salinity with groundwater levelfluctuation
by precipitation evaporation and river stage Dogan et alApaydin Jan et al Hong and Wan and Carretero and Krusefound that precipitation was one of the dominant factors thatcontributed to groundwater level fluctuation [13 15ndash18] Inour study the groundwater levels quickly changed followingeach precipitation event After rainfall the groundwater levelpresented a linear downward trend because of evaporationuntil the next precipitation event occurred The groundwaterlevel was affected not only by precipitation and evaporationbut also by the river stage
42 Effects of Precipitation Dilution on Dynamics of Ground-water Salinity The groundwater salinity can be reduced afterthe recharge of precipitation events Research showed thatthe groundwater salinity changes according to precipita-tion events Wang et al pointed out that the precipitationinfiltrated and leached downward to recharge groundwaterwhich could refresh and dilute the salt of the soil wateror groundwater during the rainy season [6] Wang et alobserved that during dry seasons shallow groundwaterwould be sanitized because of the evaporation and conden-sation effects in the north China plain [6] Rabbani et alconfirmed that saline water starts to penetrate inland duringwinter months when river flow is low and groundwaterlevel decreases as a result of climate change in Bangladesh[12] These studies indicated that the shallow groundwatersalinity would increase by evaporation in the condition ofno precipitation or saline water penetrating In our studyhigh precipitation decreased the salinity concentration ingroundwater during the wet season and continues evapo-ration increase salinity dramatically during the dry seasonThe amount of precipitation serves an important function insalt dilution Taking advantage of precipitation can be a goodmethod to control groundwater salinity in a coastal plain
43 Variations in Groundwater Level Influence on Ground-water Salinity According to the entire study time seriesgroundwater salinity changed according to the fluctuationof groundwater level During the dry season the correlationcoefficient between the groundwater level and salinity washigher than that during the wet season The fluctuationsof groundwater level were mainly caused by precipitationand evaporation in wet season while in dry season thegroundwater level was mainly affected by the water level ofLiangduo River and groundwater salinity concentration wasincreased sharply by seawater intrusion Zhou et al foundthat the saltwater intrusion is mainly controlled by riverdischarge and tidal current in Zhujiang River Estuary [19] Itis also related to wind amplitude and direction and sea levelrising A deep mechanism of saltwater intrusion should beinvestigated For a clearer mechanism of saltwater intrusionin this study area not only climate factors but also moreinfluencing factors as above can be researched And spatialanalysis should be focused on
5 Conclusions
In coastal plain of eastern China the average depth ofgroundwater level is shallow and easily affected by climatefactors (precipitation and evaporation) and river stage Theinfluencing factors on the groundwater level were in theorder precipitation gt river stage gt evaporation The ground-water salinity is influenced by climate factors groundwaterlevel and seawater intrusion Precipitation infiltrated intogroundwater and diluted the salinity so the groundwatersalinity fluctuated with precipitation events Between twoprecipitation events groundwater salinity increased withevaporation Groundwater salinity changed with the fluctu-ation of groundwater level and significant correlation wasfound between them (119875 lt 001) In the study periodthe groundwater salinity fluctuated frequently During wetseason it maintained in a low salinity level It increasedcontinuously and reached a maximum value in Decemberduring the dry season The result indicated that seawaterintrusion occurred in the coastal plain in dry season
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
This study was financially supported by the Public WelfareIndustry Special Funds for Scientific Research Projects of theMinistry of Water Resources (Grant no 200801025) and theInnovative Project of Scientific Research for Postgraduatesin Ordinary Universities in Jiangsu Province (Grant noCXZZ13 0267) The authors thank Jiangsu Province Hydrol-ogy and Water Resources Investigation Bureau for providingthem with climate data
8 Journal of Chemistry
References
[1] P KumarM Tsujimura TNakano andTMinoru ldquoTime seriesanalysis for the estimation of tidal fluctuation effect on differentaquifers in a small coastal area of Saijo plain Ehime prefectureJapanrdquo Environmental Geochemistry and Health vol 35 no 2pp 239ndash250 2013
[2] M A T M T Rahman R K Majumder S H Rahmanand M A Halim ldquoSources of deep groundwater salinity inthe southwestern zone of Bangladeshrdquo Environmental EarthSciences vol 63 no 2 pp 363ndash373 2011
[3] Y Iwasaki M Ozaki K Nakamura H Horino and SKawashima ldquoRelationship between increment of groundwaterlevel at the beginning of irrigation period and paddy filed areain the Tedori River Alluvial Fan Area Japanrdquo Paddy and WaterEnvironment vol 11 no 1mdash4 pp 551ndash558 2013
[4] Z Chen S E Grasby and K G Osadetz ldquoRelation between cli-mate variability and groundwater levels in the upper carbonateaquifer southern Manitoba Canadardquo Journal of Hydrology vol290 no 1-2 pp 43ndash62 2004
[5] Z Chen S E Grasby and K G Osadetz ldquoPredicting averageannual groundwater levels from climatic variables an empiricalmodelrdquo Journal of Hydrology vol 260 no 1ndash4 pp 102ndash117 2002
[6] SWang X Song QWang et al ldquoShallow groundwater dynam-ics and origin of salinity at two sites in salinated and water-deficient region of North China Plain Chinardquo EnvironmentalEarth Sciences vol 66 no 3 pp 729ndash739 2012
[7] S M Praveena M H Abdullah K Bidin and A Z ArisldquoUnderstanding of groundwater salinity using statistical mod-eling in a small tropical island EastMalaysiardquo Environmentalistvol 31 no 3 pp 279ndash287 2011
[8] D Liu X Chen and Z Lou ldquoAmodel for the optimal allocationof water resources in a saltwater intrusion area a case study inpearl river delta in Chinardquo Water Resources Management vol24 no 1 pp 63ndash81 2010
[9] Z Li C Zhang and W Zhu ldquoThe present and analysis of thesea water intrusion in coastland of Rizhaordquo Hydrogeology andEngineering Geology vol 36 no 5 pp 129ndash132 2009 (Chinese)
[10] J G Redwood PumpRecharge Rate Affects Saltwater Intrusion2004 httpwwwsolinstcomresourcespapers101c4saltphp
[11] G H P Oude Essink ldquoSalt water intrusion in a three-dimensional groundwater system in the Netherlands a numer-ical studyrdquo Transport in Porous Media vol 43 no 1 pp 137ndash1582001
[12] G Rabbani A A Rahman and N Islam ldquoClimate change andsea level rise issues and challenges for coastal communitiesin the Indian Ocean Regionrdquo in Coastal Zones and ClimateChange D Michel and A Pandya Eds pp 17ndash30 The HenryL Stimson Center Washington DC USA 2010
[13] A Dogan H Demirpence and M Cobaner ldquoPrediction ofgroundwater levels from lake levels and climate data usingANNapproachrdquoWater SA vol 34 no 2 pp 199ndash208 2008
[14] Q Yong Z Zhang Y Fei et al ldquoCalculating precipitationrecharge to groundwater applying envieronmental chloridetracer methodrdquo in Proceedings of the International Symposiumon Water Resource and Environmental Protection (ISWREP rsquo11)vol 1 pp 139ndash143 Xirsquoan China May 2011
[15] A Apaydin ldquoResponse of groundwater to climate variationfluctuations of groundwater level and well yields in the Hala-cli aquifer (Cankiri Turkey)rdquo Environmental Monitoring andAssessment vol 165 no 1ndash4 pp 653ndash663 2010
[16] C-D Jan T-H Chen and H-M Huang ldquoAnalysis of rainfall-induced quick groundwater-level response by using a Kernelfunctionrdquo Paddy and Water Environment vol 11 no 1ndash4 pp135ndash144 2013
[17] Y-M Hong and S Wan ldquoForecasting groundwater level fluctu-ations for rainfall-induced landsliderdquo Natural Hazards vol 57no 2 pp 167ndash184 2011
[18] S C Carretero and E E Kruse ldquoRelationship between precip-itation and water-table fluctuation in a coastal dune aquiferNortheastern coast of the Buenos Aires province ArgentinardquoHydrogeology Journal vol 20 no 8 pp 1613ndash1621 2012
[19] W Zhou D Wang and L Luo ldquoInvestigation of saltwaterintrusion and salinity stratification in winter of 20072008 inthe Zhujiang River Estuary in ChinardquoActa Oceanologica Sinicavol 31 no 3 pp 31ndash46 2012
[1] P KumarM Tsujimura TNakano andTMinoru ldquoTime seriesanalysis for the estimation of tidal fluctuation effect on differentaquifers in a small coastal area of Saijo plain Ehime prefectureJapanrdquo Environmental Geochemistry and Health vol 35 no 2pp 239ndash250 2013
[2] M A T M T Rahman R K Majumder S H Rahmanand M A Halim ldquoSources of deep groundwater salinity inthe southwestern zone of Bangladeshrdquo Environmental EarthSciences vol 63 no 2 pp 363ndash373 2011
[3] Y Iwasaki M Ozaki K Nakamura H Horino and SKawashima ldquoRelationship between increment of groundwaterlevel at the beginning of irrigation period and paddy filed areain the Tedori River Alluvial Fan Area Japanrdquo Paddy and WaterEnvironment vol 11 no 1mdash4 pp 551ndash558 2013
[4] Z Chen S E Grasby and K G Osadetz ldquoRelation between cli-mate variability and groundwater levels in the upper carbonateaquifer southern Manitoba Canadardquo Journal of Hydrology vol290 no 1-2 pp 43ndash62 2004
[5] Z Chen S E Grasby and K G Osadetz ldquoPredicting averageannual groundwater levels from climatic variables an empiricalmodelrdquo Journal of Hydrology vol 260 no 1ndash4 pp 102ndash117 2002
[6] SWang X Song QWang et al ldquoShallow groundwater dynam-ics and origin of salinity at two sites in salinated and water-deficient region of North China Plain Chinardquo EnvironmentalEarth Sciences vol 66 no 3 pp 729ndash739 2012
[7] S M Praveena M H Abdullah K Bidin and A Z ArisldquoUnderstanding of groundwater salinity using statistical mod-eling in a small tropical island EastMalaysiardquo Environmentalistvol 31 no 3 pp 279ndash287 2011
[8] D Liu X Chen and Z Lou ldquoAmodel for the optimal allocationof water resources in a saltwater intrusion area a case study inpearl river delta in Chinardquo Water Resources Management vol24 no 1 pp 63ndash81 2010
[9] Z Li C Zhang and W Zhu ldquoThe present and analysis of thesea water intrusion in coastland of Rizhaordquo Hydrogeology andEngineering Geology vol 36 no 5 pp 129ndash132 2009 (Chinese)
[10] J G Redwood PumpRecharge Rate Affects Saltwater Intrusion2004 httpwwwsolinstcomresourcespapers101c4saltphp
[11] G H P Oude Essink ldquoSalt water intrusion in a three-dimensional groundwater system in the Netherlands a numer-ical studyrdquo Transport in Porous Media vol 43 no 1 pp 137ndash1582001
[12] G Rabbani A A Rahman and N Islam ldquoClimate change andsea level rise issues and challenges for coastal communitiesin the Indian Ocean Regionrdquo in Coastal Zones and ClimateChange D Michel and A Pandya Eds pp 17ndash30 The HenryL Stimson Center Washington DC USA 2010
[13] A Dogan H Demirpence and M Cobaner ldquoPrediction ofgroundwater levels from lake levels and climate data usingANNapproachrdquoWater SA vol 34 no 2 pp 199ndash208 2008
[14] Q Yong Z Zhang Y Fei et al ldquoCalculating precipitationrecharge to groundwater applying envieronmental chloridetracer methodrdquo in Proceedings of the International Symposiumon Water Resource and Environmental Protection (ISWREP rsquo11)vol 1 pp 139ndash143 Xirsquoan China May 2011
[15] A Apaydin ldquoResponse of groundwater to climate variationfluctuations of groundwater level and well yields in the Hala-cli aquifer (Cankiri Turkey)rdquo Environmental Monitoring andAssessment vol 165 no 1ndash4 pp 653ndash663 2010
[16] C-D Jan T-H Chen and H-M Huang ldquoAnalysis of rainfall-induced quick groundwater-level response by using a Kernelfunctionrdquo Paddy and Water Environment vol 11 no 1ndash4 pp135ndash144 2013
[17] Y-M Hong and S Wan ldquoForecasting groundwater level fluctu-ations for rainfall-induced landsliderdquo Natural Hazards vol 57no 2 pp 167ndash184 2011
[18] S C Carretero and E E Kruse ldquoRelationship between precip-itation and water-table fluctuation in a coastal dune aquiferNortheastern coast of the Buenos Aires province ArgentinardquoHydrogeology Journal vol 20 no 8 pp 1613ndash1621 2012
[19] W Zhou D Wang and L Luo ldquoInvestigation of saltwaterintrusion and salinity stratification in winter of 20072008 inthe Zhujiang River Estuary in ChinardquoActa Oceanologica Sinicavol 31 no 3 pp 31ndash46 2012
