-
Eco. Env. & Cons. 18 (4) : 2012; pp. (835-847)Copyright@ EM
InternationalISSN 0971–765X
*Corresponding author: e-mail: [email protected]. Ph.D.
Student, 2. Associate Professor, 3. Professor 4. Assistant
Professor
Estimation of sedimentation in Karaj and Torogh Damreservoirs
(Iran) by hydrological models andcomparison with actual sedimentAli
Reza Roshani1,*, Abolfazl Mosaedi2, Hossein Sedghi3, Hossein
Babazadeh4 andMohmmad Manshouri5
1Hydrology and Water Resource Eng, Islamic Azad University,
Science and Research Branch of Tehran,Iran2Faculty of Natural
Resources and Environment, Ferdowsi University of Mashhad,
Iran3,4,5Faculty of Agriculture and Natural Resources, Islamic Azad
University, Science and ResearchBranch of Tehran, Iran
ABSTRACT
The most important practical and critical problem related to the
performance of reservoirs is the estima-tion of storage capacity
loss due to sedimentation process. Sedimentation triggers several
importantissues such as operation and maintenance of engineering
infrastructures, economical feasibility of theproject,
environmental problems with social aspects upstream and downstream,
increasing evaporationfrom the surface of the reservoir and reduced
flood attenuation and changes in water quality. Palmieri etal.
(2001) reports, that the loss in volume capacity requires an annual
replacement cost of US$ 13 billiondollars. Although suspended
sediment load can be predicted using numerous developed methods
includ-ing remote sensing, hydrographic survey, hydrologicy and
mathematical and computer models theirresults often differ from
each other and Every of these equations are gained based on climate
or labora-tory conditions in different places in the world and they
have different factors for determining transport-ing sediment
amount. These methods are cumbersome, time consuming and expensive.
There is a needfor developing simple methods, which require less
time and are cost. In the present study, six differenthydrology
models were tested using measured data based on effective factor of
sediment transfer such astime of measurement for determining
suspended sediment load on the reservoirs of Karaj and Torogh onthe
Karaj and Torogh Rivers catchments area, which are located in Iran
between 1961-2007 and 1978-2009respectively. At the end, the
results of developed models were compared together and with actual
amountof sediment obtained from primary and secondary area –volume
height- curves. The Mean Squared Error(MSE), Root Mean Squared
Error (RMSE), are used as error evaluation criteria to verify, and
compare theresults of developed models and select the best model.
The results of this research demonstrated that themodel B, based on
a monthly data analysis, had the least root mean squares errors for
the inlet hydro-metrical stations of Karaj and Torogh Dams and was
selected as the best model. The volume of annuallysedimentation in
Karaj dam between the years 1961-2007 was 4810000m3 while the
annual sedimentationby means of hydrograph was estimated 510000m3,
which confirms the high accuracy of the model. Themodel A based on
total data analysis and without separation of data had the highest
root mean squareserrors in Karaj hydrometrical station and was the
most undesirable model.
Key words :Sedimentation, Dam reservoirs, Surface-volume-height
curve, Karaj reservoir, Torogh reservoir, Root MeanSquared
Error
(Received 10 June, 2012; accepted 25 July, 2012)
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836 Eco. Env. & Cons. 18 (4) : 2012
Introduction
Sedimentation in dam reservoirs is one of the funda-mental
problems in water resources utilities and de-signing Hydraulic
structures after construction of adam. Deposit of the sediment
materials, which aretransferred from land surface, valleys, and
moun-tains, in dams reservoirs not only decreases the damvolume,
have a direct effect on agriculture, decreasedrinking water and
reservoir installations, but alsoforms swamps in upper lands
causing more power-ful erosion in downstream and consequently
lowerflood control of the reservoirs. Therefore, it may cometo
hinder the reservoir operation, besides causingseveral kinds of
environmental problems. Reservoirsaround the world are losing on
average about onepercent of their storage capacity annually
(WCD,2000), causing serious problems for water and elec-tricity
supply, flood control but also for ecosystemdevelopment up-and
downstream of large dams.
The problems of sedimentation in reservoirs is in-crease
throughout using this installation. Each yearabout 20 billion tons
of sediments are transported bythe rivers of the world and
deposited in still water(Mirbagheri, 1989). In Iran due to lack of
taking anyserious action and protecting water resources,
con-siderable damages are caused due to flooding andsedimentation
so that over 100 million tons of sedi-ment is deposited annually in
reservoirs and reducesmanageable capacity due to sedimentation
(Masjedi,1999).Therefore, paying more attention than before tothe
problems of erosion and sedimentation has beenfollowed more
seriously. According to the IranianCommittee of large dam’s report,
erosion and sedi-mentation are two of the most important problems
of21st Century.
Because of higher water rate consumption the sig-nificance of
studying sedimentation in reservoirs (ei-ther directly or
indirectly) is more emphasized.
Sedimentation is regarded as a very serious andimportant natural
hazard in developing countries.The World Bank has estimated the
equivalent lostcapacity of dam reservoirs, only resulted by
sedimen-tation, to be 6 billion USD per year in 1999 that,
ofcourse, will increase by construction of more reser-voirs (Fan,
1999). Hence, estimation of suspendedload in rivers, which
constitutes the major part ofsediment deposited in dam reservoirs,
is of para-mount importance. The performed
investigationsdemonstrate that the annual average economic lossesin
America’s Dam reservoirs are $50 million, but
such an economical analysis has not been performedfor Iran.
According to a comparison that was done in1999 between Iran’s Dams
and similar dams in theU.S.A., the annual average loss of
reservoirs volumedue to sedimentation was 6-11 times further
thanthose of United States. The average annual percent-age decrease
of reservoir capacity due to sedimenta-tion has been 0.60%, and the
annual deposition yieldof watersheds of Iran has been about 8 tons
per hect-are; and only 10% of these sediments are passed ofdams and
the other 90% is settled at the bottom of thedams (Montazereion and
Aminnejad,2010).
The phenomenon of sedimentation is somethingaccidental and
complicated. The amount of sedimen-tation depends on different
factors such as the sur-face of watershed, vegetation, geological,
and rainfalltime and location distribution, its duration etc.
Sedi-ment estimation in dams’ reservoirs is a very complexproblem
due to existence of unknown factors forevaluation of reservoir’s
sediment and its volume.These items depend upon flow rate, total
sedimentload, the size of the sediment, density, trap efficiencyand
reservoir yield. There are different methods forestimation of
sediment in the reservoirs like hydrog-raphy, using mathematics and
computer methods,direct measurement of the sedimentation thickness.
.But, because of techniques’ differences and complex-ity of
sedimentation and environmental conditions,one cannot recommend a
comprehensive, economic,and exact method.
Miraboulghasemi (1994) studied various methodsof estimating
suspended loads of the rivers, andcompared the obtained results
with those of hydro-graphic studies (depth estimation) of Karoun
Dam;and demonstrated that the selected method was ofhigh accuracy.
Shahidi (1995) estimated the sedi-ment entering the dam reservoir
in Khozestan prov-ince using six hydrological methods and compared
itwith the actual amount of sediment deposited behindDez Dam. Using
sediment rating equation and corre-lating the average of classes,
he found that thismethod gave almost results as actual
measurement.
Akrami (1996) investigated six hydrological meth-ods of
sedimentation in Latian(Tehran), SefidRood(Gilan),
Esteghlal(Minab), Ekbatan(Hamadan),Mahabad (western Azarbaigan),
Doroodzan(Fars),and Dez Dams(Khozestan) in different parts of
thecountry and demonstrated that the FAO method (bymeans of
classified data) gave a closer result to sedi-mentation
studies.
Piri (2003) studied optimize relationship between
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ROSHANI ET AL 837
water and sediment discharge in Emameh water-shed. He found out
that the common models for esti-mating sediment that makes use of
only one equationas sediment rating equation have the most
erroramong other models, but the model which wasbased on dry and
wet months and discharge classifi-cation resulted in the least
square errors.
Porhemmat et al (2005); Azami et al (2005),Yousefvand et al
(2006) and Mosaedi et al (2005)showed that the average categories
method was ef-fective in improving relationship and the
coefficientcorrelation of water and sediment discharge ex-tremely
increased and took into account the effect ofseasons as well.
Tarkhorani (2001); Mohammadi OstadKelaye(2002), Mirzaei (2002);
Arabkhedri et al (2005), andHeidarnejad (2006) demonstrated that
the highestamount of root mean squares error was related toannual
USBR.
Bayatiyani (2001) studied the amount of sedimenttransferring in
Nabera River in 1986-1991 and foundout that the relationship
between sediment load anddaily discharge ( 88.171072.3 ws QQ −×= )
in the 99% confi-dence level is acceptable. Finally, he found that
spe-cial sediment load, which was about 296.5 tons persquare
kilometer to 1287 tons per square kilometer,was changing in years
1986-1991.
Asselman (2000) evaluated the sediment ratingcurve as an
exponential function in several locationsof the Rhyn River and it
branched and analyzed theerrors and mistakes of this evaluation and
found thatunique differences in the forms of these diagramswere
dependent on sediment load characteristics. Healso used from root
of mean squares errors to find thebest model.
Horowits (2002) evaluated the Mississippi Riversuspended load
using sediment rating curve, hefound that in order to have the best
investigation ofthe annual sediment load in 20 year data set,
sedi-ment rating curve can be used.
Benkhald et al. (2003) performed a qualitativeanalysis for the
amount a and b of sediment ratingcurves and demonstrated that there
is a strong rela-tionship between the amount of (a) and water
dis-charge in dry years and factor (a) showed a corre-spondent
erosion with water discharge in dried yearperiod, While factor (b)
was correspondent to waterdischarge only during rainfall period.
Their re-searches demonstrated that the relationship
betweensediment capacity and water discharge was under
the effect of rainfall, the amount of runoff, and
soilmoisture.
Alexandrov et al. (2007) illustrated that the meth-ods which are
based on precipitation in spring andautumn that the result of flood
flow are related towater discharge, and the methods based on
winterrainfalls are relateted to the type of running.
Achite et al.(2007) firstly explained that the pre-dicted
amounts were 20-25% more than realamounts. Secondly, according to
available time se-ries, more precise predictions need longer time
peri-ods. Also, the most amounts of sediments were due tospring and
autumn. They also suggested that formore accurate investigation,
climatologicallychanges should be considered.
Shahouyee (1995) investigated the amount ofsediments in Qeshlagh
Dam reservoir. The amountof annual erosion was about 143 tons per
square ki-lometer, and it was 1/3 less than the suggestedamount.
Rahnamaei (1995) studied mathematical -experimental methods for
estimating sediment indam reservoirs, and compared their results
with fieldmeasurements for Karaj Dam.
Mutsvangwa (1999) studied sediment depositionfor some dams in
Zimbabwe using mathematicaland experimental methods and concluded
that ex-perimental methods were give better results
thanmathematical method.
Syvitski et al (2000) studied the relationship be-tween sediment
rating parameters and environmen-tal conditions (morphology, river,
climatology …) in59 hydrometric stations in North America and
foundthe sediment rating equation coefficients and con-cluded that
there is a close relationship between envi-ronmental variables and
sediment rating coeffi-cients for rivers with 20 cubic meter per
second waterdischarge.
Ferrari et al. (2006) demonstrated that the shapeand how the
operation of the reservoir are effectiveon the location and type of
sedimentation.
Jain (2001) developed sediment rating curves bymeans of
Artificial Neural networks (ANN) for sedi-ment volume in the
Mississippi River and observedthat the results of this method was
close to the ob-served amounts in comparison with common
tech-niques. Jain et al (2002) estimated the amount of sedi-ments
in the Bahkara Dam Reservoir in the West ofHimalaya by means of
remote measurement and theywere comparable with the results of
topography.
Jothiprakash et al (2009) investigated a period of32 years
statistics by means of SPSS 11.5 and Matlab
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838 Eco. Env. & Cons. 18 (4) : 2012
and offered a very precise estimation of sediment vol-ume in
Goubidisagar Dam in India.
Hemadi (1999) investigated the sedimentationprocess in Shahid
Abbaspour Dam (Karoun) Iran bymeans of HEC-6 software and found out
that at inter-vals of about 90 years of operation Karoun’s Dam,the
volume of sediment is about 52% of the reservoirinitial
volumes.
The scope of this study is the suspended sedimentestimation of
Karaj and Torogh Dam using an hy-drometry methods to get more
accurate results com-pared to the other methods. Six methods are
trainedusing measured water and sediment discharge dataof Sira,
Bylaghan and kartian gauging station whichis located at the
entrance and output of mentioneddam in Iran.
Methods and Materials
The Study Area
The researcher has selected the study area because ofits
reliable statistical periods and its relatively differ-ent climatic
conditions. For this reason, the twoDams of Karaj and Torogh were
selected. The Toroghdam is situated in Khorasan Razavi Province
withover 20 years lifetime, and the Karaj dam (Amir Kabirdam),
which is one of the most important dams in thecountry, is located
in the North Eastern of Karaj.These two dams are very important
because theyprovide drinking water and agricultural water forthe
surrounding areas.
Torogh Dam
The watershed of the Torogh reservoir is located inNorth-East of
Iran and in 25 kilometers away inSouthEast of Mashhad, between
latitude 36° 15' to36° 17’North and longitude 59° 18' to 59° 36'
East.This reservoir is used as a seasonal flood
regulatingstructure, for irrigation of some 1700 ha of
agricul-tural lands downstream of Torogh Dam.
The Torogh Dam is a concrete dam and is locatedon the Torogh
River. The dam height from the foun-dation is 81 meters and its
crest length 322 meters.The useful volume of the dam between levels
1160-1217 is about 35 million cubic meters. The ToroghRiver is the
most important permanent river in thesouthern part of Mashhad city,
which controls themain drainage system in the region. It rises
fromNorth Binalod Mountains and flows from southwest
to southeast along the Mashhad Plain and the sea-sonal rivers
such as Ardameh flow during winterand spring when the precipitation
was at its peak.The result of review the last 38 years record
showedthat available surface water in Torogh Dam area is
Fig. 1. The Discharge Variable in Torogh Dam Watershed(MCM)
very much depended on climate condition. Figure 1shows that
amount of discharge difference between1969 until 2005 is very high
and also this period isinclude some drought period in this region.
The esti-mated water supply for agricultural consumptionwas 8.5 MCM
but water demand in this area for agri-cultural consumption was
about 10.5 MCM. There-fore agriculture section in this region has
been 2MCM water deficits in summer. Hydrographic sur-vey of this in
2002 and 2008 has been reported.
Karaj Dam
This dam is located on the Karaj River. The initialstudies for
Amirkabir Dam took 22 years until 1956when formal proceedings began
and the dam wasconstructed in the period from 1957 to 1961. TheAmir
kabir Dam was built as a multi-purpose dam toprovide tap water for
Tehran alongside agriculturaldevelopment in Karaj. It supplies the
irrigation de-mand of over 50,000 hectares of farm land near
Karaj.The power plant has been connected to the nationalelectricity
network for over 46 years and has a capac-ity of 90 megawatts. The
ecliptic concrete structure is180 meters high, with 30 meters
length on bottomand 390 meters on top and its watershed is 764
kilo-meters long. The average annual water inflow to itsreservoir
is 472 million cubic meters. The total capac-ity of the dam’s
reservoir is 202 million cubic meters.The bottom elevation of
reservoir and normal watersurface elevation of reservoir are 1545
meters and1610 meters respectively.This was the first
multi-func-tional dam in the country. Its spillway discharge
ca-pacity is 1450 cubic meters per second. The highestpoint of the
watershed is about 4200m and The low-
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ROSHANI ET AL 839
est point is the location of the dam, 1600 m the water-shed for
Karaj Dam is bordered in the north by thewatershed of Mazandaran,
Lar and Taleghan Riverand in the south, east and west by watershed
of theJajrood, Kardan and northern Tehran River. The cli-mate of
the region is influenced by weather frontsfrom across the
Mediterranean sea. The river is 66.2km, which enters the Karaj Dam
in Sira location(Ministry of power1991). This dam has got two
inputand output hydrometric stations which are calledSira and
Beylaghan whose flow and sediment dis-charge measurements have been
started from theyears 1954 and 1967 respectively, and also
inBeylaghan station the flow discharge measurementwas started in
1947 and its sedimentation samplingin 1968.
Specific gravity
Computation of the storage useful life requires theknowledge of
sediment trapping efficiency, the sedi-ment unit weight or bulk dry
density, the incomingflow and sediment. Unit weight, specific
weight andbulk density are all used to express the dry weightper
unit volume of a bulk sediment sample.
The dry bulk density of sample is estimated basedon intact dried
sample and its Initial volume. Theamount of this quantity depends
on the depth ofsediment, aggregation, and … which is derived
fromthis equation:
mP =
vFor estimating a Bulk density one can use a simi-
lar equation but considering that the wet weight ofthe sample is
replaced with dried sample.
Sediment Rating Equation
The changes of sediments suspended load has aclose relationship
with flow discharge. Unless sedi-ment concentration is constantly
recorded, hydrolo-gists uses of the Sediment Rating Equation for
esti-mating the sediment load.
The relation that one can establish between sedi-ment discharge
and flow discharge is as follows:
QS: sediment discharge, usually in terms of tons perday (ton/day
)Qw: flow discharge usually in terms of m3/sa and b: equation
constant coefficient
In fact, by measuring the flow discharge, samplingthe deposited
particles and experimental viscometryand preparing different curves
and related calcula-tions, one can find out the values of water and
sedi-ment crossing the sediment measurement station overlong
periods of time.
Hydrologists, based on researches, have come tothis conclusion
that there is a moderately good rela-tionship between suspended
sediment concentrationand discharge, i.e. the higher the discharge
thehigher the suspended sediment concentration. How-ever, this
relationship is to a high degree of variabil-ity and error,
especially when the suspended sedi-ment is comprised mainly of silt
+ clay.
In order to change sediment concentration to sedi-ment discharge
is used from the following equation:
Qs: sediment discharge (ton/day)Qw: flow discharge (m3/s)C: the
average concentration of suspended sediment(mgr/lit)
In this study, the first based on equation (3) sedi-ment
concentrations was converted to sediment dis-charge. Then, the
regression relationship was estab-lished between corresponding data
of water dis-charge and suspended sediment discharge based onthe
investigated models, and then the coefficients ofsediment rating
equation (b, a ) were obtained, whileconsidering the factors
affecting sediment transportthat may produce errors , such as
measurement timeor flow condition, for this purpose five models
wereexamined as follows:
Model A, This model is the simplest method of es-timating
sediment discharge. The sediment flow isestimated based on all
measured data and withoutconsideration of the time of measurements
other clas-sification of the data.
Model B, In this model, the sediment dischargecan be studied
based on monthly separations of dataand for each month of the year
due to their long -term data, sediment rating curve and its
equation isobtained.
Model C, the estimation of sediment flow is per-formed based on
a seasonal separation of data(spring, summer, autumn and winter)
and then thesediment rating curve is estimated.
Model D, the separation of data is based on highwater and low
water flow months. A high watermonth has higher mean monthly flow
rates thanmean annual discharge rate or is equal to it. A low
... (1)
.. (3)
.. (2)
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840 Eco. Env. & Cons. 18 (4) : 2012
water month has a lower mean monthly dischargerate than the mean
annual flow rate.
Model E, the sediment and flow rates are dividedinto the
following three groups, basedon daily flow rates:
Amounts less than mean annual dischargeAmounts greater than or
equal to mean discharge
but less than twice the mean annual flow rate.Amounts greater
than or equal to twice the mean
annual discharge.Model F: This model is known as the median
of
groups. In this model discharges are arranged basedon flow
volume (from smaller to large), then thesedata are divided into
category (nearly ten or more). Inthe next part, the mean discharge
of each group andaverage sediment discharge are estimated. After
that,between these data series regression relationship isfitted and
it has high correlation coefficient.
To select the best model, the root mean squareserrors were used
.To obtain the above results, EXCELand SPSS software was used.
Estimating Suspended Load, Total load, andSediment volume
In order to estimate the suspended load, as it wasexplained in
the beginning, in hydrometricstations,the regression relationship
was establishedbetween corresponding data of water discharge
andsuspended sediment discharge based on the investi-gated models,
and then sediment rating equation andthe coefficients of it (b, a
,which are the distance be-tween the intersection of the best
fitting line with ver-tical axis and origin and the slope of the
best fittingline on the logarithmic paper, respectively) are
ob-tained for different models, in the next step, using
theinvestigated models and regarding the daily flowdischarge, the
amount of daily suspended load is es-timated. Summing up the daily
sediment loads, onecan reckon the monthly and annual suspended
load(ton/day).Finally; The annual average suspendedload is
estimated for the whole statistical period.
Different hydraulic and hydrologic methods areused in order to
estimate bed load. In this researchfor estimating the bed load,
Because no suitable datawere available on bed load in the Karaj and
ToroghRivers, the Karaushev experimental curve was usedto determine
bed-to- suspended load ratios based onslope of the rivers. Its
value is increased in the rivers
with further slope and in the areas with less slopesthis amount
is decreased to a great extent. Accordingto Karaushev theory, this
ratio is different in the riv-ers to the topographic conditions.
Research showedthat the Karaushev theory is applicable in
Iranianrivers. In this study, primarily, based on slopes Karajand
Torogh Rivers, the ratio of the bed load to sus-pended load was
determined. Then, according toannual suspended loads and ratio
mentioned, theannual bed loads was calculated. The total
sedimentload was determined by addition of bed and sus-pended
load.
In order to estimate the sediment volume, one canmake use of
special density of the sediments in un-derstudying dams. By
dividing the sediment mass bythe average density of the sediments,
the volume ofthe sediment was obtained. Subtraction of inlet
andoutlet volume of sediment gave the volume of sedi-ment deposited
in the reservoir.
Selecting the optimal Model for estimatingsediment
To fit function to a given series, the best method isusing a
function with least free parameters and theseparameters are
selected in such a way that the differ-ence between the function
and measured data be-comes the least. Generally, performance of a
model isevaluated based on the comparison between thecomputed
output and actual data. The prediction ofeach model is evaluated
using the correlation of coef-ficient (R2), Mean Squared Error
(MSE), root meansquare error (RMSE). A RMSE is one of the most
com-monly used performance measures in hydrologicalmodeling. A
model with the minimum error wouldbe the best choice.
There are different criteria for the best fitting func-tions
which are all optional, but in the least squarecriteria is very
frequent.
Based on mean of least squares errors index, theestimated
amounts of the selected model is closer toobserved values, the sum
of squares error is reduced.Thus square mean errors which are
obtained fromdividing the squared errors to freedom degree will
beless.
Formulas for calculating indexes of the sum of thesquare errors,
mean of square errors, and correlationcoefficient are given as
follows:
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ROSHANI ET AL 841
In theses relations:SSE: the sum of squared errorsMSE: the mean
of squared errors(MSE)m: every model’s mean of squared errorsQsio:
measurement suspended load discharge (ton/day)Qsic: estimated
suspended load discharge (ton/day)Qwi: measurement flow discharge
(m3/s)
in reservoirs. In this research, the first in
hydrometricstations, the regression relationship was
establishedbetween corresponding data of water discharge
andsuspended sediment discharge rate based on the in-vestigated
models, and then sediment rating equa-tion and the coefficients of
it, the correlation of coeffi-cient (R2), the sum of squared errors
(SSE), the MeanSquared Error (MSE), Root Mean Squared Error(RMSE)
were extracted. (Table 1 as Samples in sira).The results of these
rating equation for the inlet sta-tion of Karaj (Sira), which are
compared in Table 1,reveal that the rating equation developed by
dataclassification method is more accurate compared toother methods
.The sediment rating curves in amonthly model were then illustrated
as Samples insira station of Karaj Dam (Fig 2 - the x-axis is
waterdischarge in [m3/s] and y-axis is sediment dischargein
[tons/day]). In the next step, histograms of RootMean Squared Error
of the models in stations weredrawn to find model with minimum
error. (fig, 3 and4). Considering the extracted equation for
everymodel and the daily flow rates, the amount of sus-pended load
in the input and output hydrometricstations was determined for
Karaj Dam based on theinvestigated models. the bed – to - suspended
loadratio was obtained as 2 and 0.45 for sira andBilghan stations
respectively (by means ofKaraushev Graph) and by multiplying this
ratio insuspended load was calculated The bed load in bothstation.
Total sediment was obtained by addition ofbed and suspended load in
each model (Table 2).The difference between the total sediment in
inlet(Sira) and outlet (Bilghan) stations, was calculatedthe weight
of deposited sediment per tons.
Generally the curves of the surface-volume andheight are based
on volume unit; therefore, For com-putation of sediment volume we
used from sedimentweight and density of it (1.4 ton/m3- water
ResearchCenter of Iran) and divided these two parameters to-gether
for both station under study (Table 2).
The results obtained show that in both station Siraand Beylaghan
after model F, model B, in which theseparation of data was made
monthly, had the leastroot mean squares errors and was selected as
the bestmodel.
For further investigation of the accurate modelsand selection of
an optimal model after determiningthe amount of error for each
model, the estimatedsediment of each model was compared with
actualamount of sediment obtained from primary and sec-ondary area
–volume curves of surface-volume-
2)log(log11
2)log(log
)log(log1
)log(log
)(
12)log(log
wQwiQn
i
n
isQsiQ
wQwiQn
isQsiQ
R
DFESS
MEMS
DFESS
EMS
n
i sicQsioQESS
−∑=
∑=
−
−∑=
−
=
∑
∑=
=
∑=
−= .. (4)
.. (5)
.. (6)
.. (7)
... (8)
Qw: the average measurement flow discharge (m3/s)Qs: the average
measurement suspended load (ton/day)DF: the degree of freedom
Qsio= observed sediment discharge , Qsic = calcu-lated sediment
discharge.
The closer this feature to zero, the more careful themodel will
be.
In this research, after separation of the data basedon discharge
rate and time of measurement, analyzethem and determining the
sediment transport equa-tion, tables variance analysis, error
squares, errorsquare mean, the root of error square mean, data
cor-relation coefficient, and sediment transferring equa-tion
coefficients were obtained in each case. the mostsuitable model was
selected based on root meansquare error index. In this study, in
addition apply-ing statistical features such as RMSE, estimated
sedi-ment volume of each model in the two understudy-ing dam
reservoirs was compared with actual de-posited sediment volume
obtained from primary andsecondary area- volume curves until the
accuracy ofthe models and optimization model is introduced.
Conclusions and Discussion
The objective of this paper was to investigate hydrol-ogy models
in estimation of sediment concentration
-
842 Eco. Env. & Cons. 18 (4) : 2012
height between the years 1961-2007.According to the results,
model B
was introduced as the sediment ap-propriate transport model in
theKaraj Dam hydrometric station inwhich the separation of data
wasmade monthly, and was selected asthe best model. In fact this
model ishighly in accordance with the ef-fects of climate factors
(such as rain-fall) and hydrological factors (suchas runoff) which
were important inmonthly separation of data. In figure5 showed this
fact. After themonthly model (model B), the sea-sonal model (model
C), then classi-fied model (model E), and after thatmodel D could
estimate the amountof sediment more precisely and re-spectively.
The comparison of re-sults showed that the monthlymodel predicted
the deposited sedi-ment volume 94% of the actualamount of sediment
for the periodbetween 1961 to 2007. Despite thefact that model F
reckoned the leasterror square mean, it could not esti-mate the
sediment more than 34%and relatively had the least
precisecapability.
Torogh Dam was the secondstudied case because of the
climaticconditions in most summers and au-tumns the entering river
was dry orsemi- dry; and little or no sedimententered the dam this
seasons. There-fore, no sediment rating curve wasdrawn for this
seasons. The ob-tained results showed that sedimentrating equation
coefficient are afunction of selected model and theway these data
are separated. Ac-cording to the criterion of leastsquares error,
calculation the vol-ume of sediment between the years2002-2007 and
comparing it withactual estimated sediment volumeby means of
surface-volume-heightdiagrams, also, in this case monthlymodel has
the best results among allsix evaluated methods and was se-Ta
ble
1.Se
dim
ent r
atin
g eq
uatio
ns a
nd R
oot M
ean
Squa
re E
rror
in s
ira
stat
ion
of K
araj
Dam
Mod
elD
ata
Sepa
ratio
nN
DF
ab
R2
Ra.
Q w
bSS
EM
SE(M
SE) m
RMSE
Mea
suri
ng ti
me
Dat
a cl
assi
ficat
ion
AD
urin
g Ye
ar—
—13
5813
560.
484
2.38
0.76
0.87
178
0.48
4*Q
w^2
.38
389.
20.
2870
210.
288
0.53
6656
Janu
ary
——
4240
1.91
11.
716
0.7
0.83
666
1.91
1*Q
w^1
.716
1.9
0.04
750.
243
0.49
295
Febr
uary
——
6058
1.27
82.
070.
660.
8124
041.
278*
Qw
^2.0
78.
550.
1474
14M
arch
——
138
136
0.39
62.
510.
760.
8717
80.
396*
Qw
^2.5
127
.04
0.19
8824
Apr
il—
—30
129
90.
172.
720.
710.
8426
150.
17*Q
w^2
.72
74.2
40.
2482
94M
ay—
—35
034
80.
078
2.91
90.
760.
8717
80.
078*
Qw
^2.9
1955
.64
0.15
9885
BJu
ne—
—17
517
30.
009
3.33
0.77
0.87
7496
0.00
9*Q
w^3
.33
26.0
70.
1506
94Ju
ly—
—84
821.
217
1.65
80.
130.
3605
551.
217*
Qw
^1.6
5876
.08
0.92
7805
Aug
ust
——
3331
1.87
1.93
0.36
0.6
1.86
9*Q
w^1
.931
17.1
60.
5535
48Se
ptem
ber
——
3028
2.68
31.
673
0.39
0.62
452.
683*
Qw
^1.6
739.
002
0.32
15O
ctob
er—
—60
580.
434
2.66
70.
80.
8944
270.
434*
Qw
^2.6
6711
.68
0.20
1379
Nov
embe
r—
—51
490.
201
3.1
0.79
0.88
8819
0.20
1*Q
w^3
.19.
870.
2014
29D
ecem
ber
——
3432
0.91
32.
072
0.75
0.86
6025
0.91
3*Q
w^2
.072
6.19
0.19
3438
CSp
ring
——
826
824
0.09
12.
847
0.73
0.85
440.
091*
Qw
^2.8
4717
3.4
0.21
0437
0.26
10.
5108
82Su
mm
er—
—14
714
53.
221
1.41
917
413
.190
913.
221*
Qw
^1.4
1910
7.83
0.74
3655
Aut
umn
——
145
143
0.43
32.
638
0.78
0.88
3176
0.43
3*Q
w^2
.638
30.5
30.
2134
97W
inte
r—
—24
023
80.
782.
270.
770.
8774
960.
78*Q
w^2
.27
40.2
30.
1690
34
DD
ry m
onth
s—
—44
844
60.
714
2.34
0.72
0.84
8528
0.71
4*Q
w^2
.34
100.
260.
2247
980.
267
0.51
6W
et m
onth
s—
—91
090
80.
082.
868
0.69
0.83
0662
0.08
*Qw
^2.8
6825
9.8
0.28
6123
ED
urin
g Ye
ar1
433
431
1.36
1.94
0.32
0.56
5685
1.36
*Qw
^1.9
4512
1.24
0.28
1299
0.25
30.
5029
912
306
304
0.13
82.
567
0.12
0.34
641
0.13
8*Q
w^2
.567
122.
080.
4015
793
619
617
0.05
3.03
0.63
0.79
3725
0.05
*Qw
^3.0
397
.89
0.15
8655
FD
urin
g Ye
ar—
—41
391.
369
2.24
0.94
0.96
9536
1.36
9*Q
w^2
.24
1.8
0.04
6154
0.04
60.
2144
76
-
ROSHANI ET AL 843
Fig 2. Sediment ratio curves (model B) in Sira station of Karaj
Dam
lected as the best and efficient model that this argu-ment
approves the same results of Karaj Dam. Afterthe monthly model, the
Seasonal Model had higherexactness. The table 3 illustrates
estimation of sedi-ment volume in different models of Torogh dam.
Theapplication of different techniques for estimating
thesedimentation rate in the reservoir shows that theaverage
sedimentation rate for 6 years (2002-2007) is
proximately 194.03 thousand cubic meters, whereasResults of
investigation through hydrographic sur-vey provided a sedimentation
rate of 209.52 thou-sand cubic meters for the same period. (Fig.
6).
Based on the obtained results from both dams andcomparing them
with real sediment amount showedthat model B was well enough to
predict the amountof sedimentation in the reservoir; Classification
ap-
-
844 Eco. Env. & Cons. 18 (4) : 2012
plied on water and sediment discharge, had signifi-cant impact
on the improving relation between waterand sediment discharge and
decreasing in RMSE. Inone hand, the hydrological behavior of every
under-studying station was different in predicting the sedi-ments
and this demonstrated that the climatic and
geological conditions and vegetation had effectiveimpact on
producing sediment; and one can con-clude that it is necessary to
consider other factors intransferring sediment for more precise
results.
However, one should pay attention that the moreprecise the
measurement of the water and sediment
Fig 2. Sediment ratio curves (model B) in Sira station of Karaj
Dam
-
ROSHANI ET AL 845
Fig 3. Root Means Square Error in sira station of KarajDam
Fig 4. Root Means Square Error in Beylaghan station ofKaraj
Dam
Table 2. Estimated sediment volume in two station of Sira and
Beylaghan with using different models from 1961 to2007
Model Beylaghan Hydrometric Station Sira Hydrometric Station
Volume(m3)Suspended load Bed load Total load Suspended load Bed
load Total load(tons)
A 3085976.62 1388689.48 4474666.1 10256258.74 20512517.47
30768776.21 18781507.22B 3728788.29 1677954.73 5407643.03
1191181.27 23823762.53 35735643.8 2166350054C 3201950.42 1440877.69
4642828.11 11334716.19 22669432.38 34004148.56 20979275.63D
3087058.07 1389176.13 4476234.20 11200783.8 22401567.6 33602351.4
20139720.26E 2199781.1 9989901.49 3189682.6 12696628.05 253932256.1
38089884.15 24928715.14F 6529465.79 2938259.61 9467725.39
17552006.75 35104013.5 52656020.24 30848782.03
Fig 5. Estimated sediment in different model and actualsediment
in Karaj Dam from 1961 -2007
Table 3. Estimated sediment volume in Torogh reservoir with
using different models from 2002 to 2007.
Model Station kartian Volume(m3)Suspended load Bed load(tons)
Total load(tons)
A 54794.25 164382.75 219177.005 146118.004B 72761.64 218284.9
291046.6 194031.1C 66468.75 199406.26 265875.01 177250.009D
62719.38 188158.15 250877.53 167251.69E 93011 279033 372044 248029F
137810.1 413430.18 551240.24 367493.49
Fig 6. Estimated sediment in different model and actualsediment
in Torogh Dam from 2002 -2007
-
846 Eco. Env. & Cons. 18 (4) : 2012
discharges, accurate calibration of bed load and sus-pended load
floor and using computing and artifi-cial intelligence techniques
can provide the more pre-cise capability of sedimentation in the
reservoirs.This matter can decrease dam hydrographic cost andleads
to accurate planning in water resources man-agement in dams.
Because the bed load is coefficientof suspended load cannot provide
remarkable re-sults, it is suggested that for promoting efficiency
ofthese methods, the climate and morphological condi-tions of the
rivers in the different parts of the worldshould be studied.
References
Achite, M. and Ouillon, S. 2007. Suspended sediment trans-port
in a semiarid watershed, wadi Abd, Alge-ria(1973-1995). J. Hydrol.
843 : 187-202.
Akrami, A. 1996. Sedimentation situation in Iranian Damsand a
comparison with theoretical methods. M.S.thesis. College of
Agriculture, University of TarbiatMorddaress. 174p. (in
Persian)
Alexandrov, Y., Laronne, J.B., Reid, I. 2007. Intra-event
andinter-seasonal behaviour of suspended sediment inflash floods of
the semiarid northern Negev, Israel.Geomorphology. 85-97.
Arabkhedri, M. 2005. A Study on the Suspended SedimentYield in
River Basins of Iran. Iran Water Resour. Res.J. 1( 2): 51-60. (In
Persian)
Asselman N. E. M 2000. Fitting and Interpretation of Sedi-ment
Rating Curves. J. Hydrol. 234: 234-238.
Azami, A., Najafinezhad, A., Arabkhedri, M. 2005. Evalu-ation of
hydrological models for estimating sus-pended sediment load during
base flow and floodin watershed of Elam dam. Proceedings of
3th,National Conference on Erosion and Sedimenta-tion, pp. 298-306.
(In Persian)
Benkhaled, A., Remini, B. 2003. Analysis of a sedimentrating
curve in Wahrane river basin (Algeria). Rev.Sci. Eau. 16(3) :
333-356 (article in French).
Bhutiyani M.R. 2000. Sediment Load Characteristics of
AProglacial Stream of Siachen Glacier and The Ero-sion Rate In
Nubra Valley In the Kara KoramHimalayas, India, J. Hydrol. 101
(1-4) : 275-290.
Fan, S.S. 1999. An overview of three sedimentation stud-ies in
the U.S, In A.W . Jayavardena, J.H.W. Lee, andZ.Y. Wang (Eds.).
River Sedimentation, Theory andApplications. Balkema, Rotterdam,
pp.391-396.
Ferrari, R., Collins, K. 2006. Reconnaissance techniques
forreservoir surveys. Proc. of the Eighth Federal Inter-agency
Sedimentation Conference, April 2-6, 2006,Reno, NV, USA
Heidarnejad, M., Golmayi, S.H., Mosaedi, A., Zia TabarAhmadi,
M.K.H. 2006. Modification of Sediment rat-
ing equations and estimate suspended sediment inhydrometric
station of Talezang in Iran. 7th Inter-national Conference of Civil
Engineering, 10P. (inTehran).
Hemadi, K. 1999. Evaluation of the Shahid Abbaspour reser-voir
sedimentation using HEC-6. M.S.thesis, College ofAgriculture,
Shahid Chamran University of Ahvaz.
Horowitz, A.J. 2002. The use of rating (transport) curvesto
predict suspended sediment concentration: a mat-ter of temporal
resolution. Turbidity and other sedi-ment surrogates workshop,
April 30-May2, Atlanta,GA, U.S. Geological survey. 3p.
Jain S.K. 2001. Development of integrated sediment rat-ing
curves using ANNs. J. Hydra. Engine. 127(1): 30-37.
Jain, S.K., Singh, P. 2002. Assessment of sedimentation inBhakra
Reservoir in the western Himalayan regionusing remotely sensed
data. Hydrological SciencesJournal – des sciences. Hydrologiques.
47(2) : 203-212.
Jothiprakash, V., Grag, V. 2009. Reservoir
SedimentationEstimation Using Artificial Neural Network, J.Hydrol.
Eng. 14(9) : 1035-1040.
Masjedi, M., Zaker, H. 1999. Sedimentology methods anddraining
sediments of storage dams. Proceedings ofthe 4th educational
workshop of technical commit-tee of dam hydraulics. 19p. (in
Persian)
Ministry of power 1991. A report of sedimentology andsediment
measurement of Amir Kabir Dam. Inves-tigations and Laboratories of
Tehran WaterResourses.113p.(in Persian)
Miraboulghasemi, H. 1994. Effects of dam construction
onsuspended load and the process of river erosion and
sedi-mentation. M.Sc. Thesis. College of Agriculture, Uni-versity
of Tarbiat Moddarress. (in Persian)
Mirbagheri, A. 1989. Technical studies in watershed sedi-ment
estimation. Proceeding of the 1st HydrologyConference of Iran.
College of Engineering, Univer-sity of Tehran. pp. 652-668.(in
Persian)
Mirbagheri S, Rajaei T 2006. Improving of prediction
andestimates of suspended load of rivers using artifi-cial neural
networks. Proceedings of 7th InternationalConference on Civil
Engineering. 435-443. (In Persian).
Mirzaei, M. 2002. Comparison statistics methods of
estimatingrivers suspended sediment (Gorganrood case study).
M.S.thesis. Tehran University, Natural Resources Col-lege.
Mohammadi Ostadkelaye, A. 2002. Optimization of flow dis-charge
and suspended load discharge in hydrometric sta-tions of Gorganrood
River. M.Sc. Thesis. Gorgan Uni-versity of Agricultural Sciences
and Natural Re-sources, 90p. (In Persian)
Montazereion, M.H., Aminnjad, M. 2010. Sedimentationin the
reservoir dams in Iran. Proceedings of theFirst Iranian National
Conference on Applied Re-search in water Resources.
Mosaedi, A., Shahabi, M., Mohammadi Ostadkelaye, A.
-
ROSHANI ET AL 847
2005. Survey of conversion discharge and sus-pended load terms
in Marave (Atrak) hydrometricstation. 2 th watershed and water
& soil resourcesmanagement national conference. Kerman, pp.
333-340.
Mutsvangwa, C. 1999. Sedimentation in Zimbabweandam projects, In
A.W. Jayawardena, J.H.W. Lee andZ.Y. Wang (eds) River
Sedimentation. Theory andApplications Balkema, Rotterdam,
pp.457-463.
Palmieri, A., Shah, F. & Dinar, A. 2001. Economics of
res-ervoir sedimentation and sustainable managementof dams. J.
Environ. Manage. 61: 149–163
Piri, A.S. 2003. Optimize the relationship flow and
sedimentdischarge in Amameh watershed. M.S. thesis. Depart-ment of
Natural Resources, Mazandaran University.70 p.
Porhemmat, J., Domeri Ganji, M. 2005. Analysis of sedi-ment
transport equations in hydrometric stations ofHendijan - Jarahi
watersheds. Proceedings of 3rd
National Conference on Erosion and Sedimenta-tion, pp. 265-272.
(In Persian)
Rahnamaei, D. 1995. Sedimentation in dam reservoir.Water and
Development, 1: 50-58
Syvitski, J.P., Morhead, M.D., Bahr, D.B., Mulder, T.
2000.Estimating fluvial sediment transport: the ratingparameter.
Water Resources Research. 36(9): 2747-2760.
Trkhvrany, H. 2001. Optimize the relationship between waterand
sediment discharge in watershed Lyqvan. M.S. the-sis. Agricultural
Sciences and Natural ResourcesUniversity of Gorgan, 86P.
World Commission on Dams (WCD) 2000. Dams and De-velopment: a
New Framework for Decision-Making.Earthscan Publ.London, UK.
Yousefvand, F., Ahmadi, M.Z., Ghamania, H., Golmai,
H.,Vahedimajd, A. 2006. Estimation of sediment loadand Determining
of sand harvesting capacity inRazavar River. 7th International
Seminar on RiverEngineering. University of Ahvaz.
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