WATER QUALITY TREND OF BATANG KAYAN AND ITS
RELATION TO ANTHROPOGENIC ACTIVITIES
GWENDOL YNE CHRISTOPHER
A dissertation submitted
in fulfillment of the requirement for the degree of
Master of Environmental Science (Land Use and Water Resource Management)
Faculty of Resource Science and Technology
UNIVERSITI MALAYSIA SARA W AK
2004
In Loving Memory Of
Agnes Jamuh (1932 -1990)
Christopher John (1957 -1979)
Annie John (1959 - 2000)
ACKNOWLEDGEMENT
First and foremost, I would like to express my deepest gratitude and appreciation to my
supervisor, Associate Professor Dr. Lau Seng, for without him, this study would not have
been successful. I would also like to extend my profound gratitude and appreciation to
other lecturers and academicians especially Dr. Lee Nyanti, Dr. Detlef Bringemeier, Miss
Tina Svan Hansen, Dr. Azuhan Mohamed, and Dr. Barzani. I sincerely thank them for
their dedications, invaluable advices and untiring help in the preparation of this project.
I also would like to thank the following people and organisation that have help me in
making this study a success:
• Department of Environment, Sarawak
• Sekitar Ceria Environmental Services Sdn. Bhd.
• Natural Resources and Environmental Board of Sarawak
• Alam Sekitar Malaysia Sdn. Bhd.
• Department of Irrigation and Drainage, Sarawak
• Land and Survey Department, Kuching Divisional Office
• The management of SALCRA, FELDA Sampadi, Raya Oil Palm Plantation and
other plantation smallholders
• Mr. Emak Uyu of Agriculture Department, Lundu District Branch
• Mr. Kamil of Farmers' Organisation of Lundu District Branch
• All the villagers from Kampung Selampit, Kampung Sebandi Hulu, Kampung
Sebandi Hilir, and Kampung Stunggang Dayak.
11
A special thank to all the DANIDA for the sponsorship of this programme and UNIMAS
staff, especially to SLUSE Masters Programme Coordinator, Mr. Robert Malong, for
their great and enduring administrative, technical and academic supports and other
preparatory inputs and management to ensure coherent conduct of the programme. I
would also like to thank all my friends who have helped and shared ideas with me
throughout the duration ofthis study.
Finally, I would like to express deepest gratitude and love to my mother, my uncle, my
cousins and the rest of the family who have given me all the moral support and
encouragement to bring me to where I am today. Without the presence of their support
during my studies, this project would never have been completed.
Gwendolyne Christopher
2004
iii
ABSTRACT
Biological processes, anthropogenic activities and water resources within a river basin are clearly associated. Thus, water catchment is a good boundary limit to study ecological stress. Over the years, Lundu District has undergone a lot of development especially the agriculture sector. The most dominant land uses in Batang Kayan catchment are oil palm plantations, paddy irrigation schemes, and shifting cultivations. Most of the agricultural projects are concentrated along Batang Kayan as they are depending on Batang Kayan as the source o(water. All the runoffs from the agricultural projects are drained out to Batang Kayan. Thus, a study was carried out to determine the impacts of land use changes on water quality and to evaluate the water quality trend (1997 2003) of Batang Kayan catchment in particular of the Selampit sub-catchment. Field observations, indepth interviews with the villagers, oil plantation managements and government agencies, literature search and water quality sampling and analysis gave indications of water quality issue in this catchment. They are the severe soil erosion, sedimentation and siltation, and leaching of nutrients. The water quality index (WQI) for the river began to deteriorate in 1997 with an index of 79 compared to 88 in 1996. This coincides with the beginning of the massive development of agricultural sector in that district. Human activities have thus caused significant decreased in water quality. Nonetheless, the water quality of Batang Kayan has generally improved due to the stringent enforcement by the government and currently the WQI of the river is 88.
IV
ABSTRAK
Semua proses biologi, kegiatan manusia dan sumber air dari lembangan sungai adalah berkait rapat. Oleh itu, kawasan tadahan air merupakan sam pal dan penunjuk yang baik dalam mengkaji tekanan ekologi. Daerah Lundu kian membangun terutamanya di sektor pertanian. Guna tanah yang utama di kawasan tadahan air Batang Kayan adalah ladang kelapa sawit, skim pengairan padi, dan pertanian pindah. Kebanyakan projek-projek pertanian tertumpu di sepanjang Batang Kayan kerana mereka bergantung kepada sungai tersebut sebagai sumber air. Aliran dari projek-projek tersebut disalurkan keluar ke dalam Batang Kayan. Oleh itu, satu kajian untuk menentukan kesan perubahan guna tanah ke atas kualiti air dan menilai tren kualiti air Batang Kayan telah dijalankan. Hasil kajian berdasarkan pemerhatian di kawasan kajian, temu bual bersama orangorang kampung, pengurus-pengurus ladang kelapa sawit dan pegawai-pegawai agensi kerajaan, bahan rujukan dan persampelan dan analisis air, telah menunjukkan beberapa isu kualiti air di kawasan tadahan ini seperti hakisan tanah yang serius, pengenapan dan pelodakan, serta nutrien. Berdasarkan temubual bersama orang-orang kampung, mereka bersetuju bahawa kualiti air Batang Kayan kian menurun. Indeks kualiti air Batang Kayan mula merunun pada tahun 1997 dengan nilai indeks hanya 77 berbanding dengan 88 pada tahun sebelumnya. Penurunan indeks kualiti air ini selaras dengan pembangunan pertanian yang pesat di daerah tersebut. Ini menunjukkan bahawa kegiatan-kegiatan manusia telah menyebabkan kualiti air merosot. Walau bagaimanapun, kualiti air di Batang Kayan telah meningkat secara amnya yang disebabkan oleh penguatkuasaan yang ketal dan kini indeks kualiti air bagi Batang Kayan adalah 88.
v
TABLE OF CONTENTS
Dedication
Acknowledgement
Abstract
11
IV
Abstrak V
Table Contents
List of Tables
VI
IX
X List of Figures
Chapter 1 Introduction
1.1 Introduction
1.2 Study Area
1.3 Study Objective
1.4 Significance of Study
Chapter 2 Literature Review
1
1
3
3
4
6
2.1 Importance of Water Catchment 6
2.2 Human Effects on Water Quality 8
2.3 Sources of Water Pollution 9
2.4 Case Studies on the Relation of Land Use and Water Quality 13
2.4.1 Land Use and Surface Water Quality in State of Ohio 14
Watersheds
2.4.2 Land Use Impacts on Water Quality of Lower Fraser 14
Valley, British Columbia
2.4.3 Land Use and Land Cover Change Impacts on the Water 15
Quality of Klang - Langat Basin
2.4.4 Land Use Changes in Niah Catchment and its Impacts on 16
Water Quality
Chapter 3 Materials and Methodology
3.1 Data Collection
3.1.1 Literature Search
VI
18
18
18
3.1.2 In-depth Interview 21
3.1.3 Site Observation 23
3.2 Data Analysis 23
3.2.1 Statistical Analysis 24
3.2.2 Land Use Mapping 24
3.2.3 River Classification 25
Chapter 4 Results and Discussion 27
4.1 Existing Environment 27
4.1.1 Climate and Meteorology 27
4.1.2 Topography and Soil Characteristic 29
4.1.3 Land Use and Other Anthropogenic Activities 38
4.2 Local Perception Towards the Land Use Issue, the Management 50
and Quality ofBatang Kayan
4.2.1 Pattern of Land Use 50
4.2.2 Settlement Condition 51
4.2.3 Perception on the Major Sources of Pollution to Batang 52
Kayan
4.2.4 Importance ofBatang Kayan 53
4.2.5 Comparison of Water Quality in the Past and Present 54
4.3 Water Quality 58
4.3.1 Water Quality Index 58
4.3.2 In-situ Water Quality Data 60
4.3.3 Selampit Sub-catchment Water Quality 67
4.3.4 Present Batang Kayan Water Quality Characteristics 77
ChapterS Water Quality and Anthropogenic Activities Issues 80
5.1 Soil Erosion, Sedimentation and Siltation 80
5.2 Flood Event 81
5.3 Water Quality 82
5.2.1 Total Suspended Solids (TSS) 82
5.2.2 Turbidity 83
Vll
Chapter 6
Reference
Appendices
Appendix I:
Appendix 2:
Appendix 3:
Appendix 4:
Appendix 5:
Appendix 6:
Appendix 7:
Appendix 8:
Appendix 9:
5.2.3 Ammonia Nitrogen
5.3 Absence of Cover Crops and Buffer Zones
Conclusion and Recommendations
6.1 Conclusion
6.2 Limitation
6.3 Recommendation
83
84
85
85
87
87
88
Batang Kayan In-Situ Water Quality Data (1997 2003) 93
Interim National Water Quality Standard 97
Interim Water Quality Classification 101
Legend of Agriculture Capability of Batang Kayan Catchment 104
Soil
Pictures from Site Observation 106
Questionnaire for Plantation Managers 114
Questionnaire for Villagers 118
Rainfall and Evaporation Data 123
Raw Water Quality of Kampung Selampit Station (1997- 2003) 126
Appendix 10: Water Quality Trend of Batang Kayan (1985 - 2003) 128
Vlll
LIST OF TABLES
Table 2.1: Spatial Dimensions of the Impacts of Human Activities 7
Table 2.2: Classes of Non-Point Source Pollution 10
Table 3.1: Raw Data and Their Sources 19
Table 3.2: Best-Fit Equation for the Estimation of Various Sub-Index Values 26
Table 4.1: The Soil Group Found within Batang Kayan Catchment 30
Table 4.2: Soil Erodibility Classification 35
Table 4.3: Soil Erodibility Classes for Soil Family Found in Batang Kayan 38
Table 4.4: Land Use Classification and its Area 39
Table 4.5: Settlements Along Batang Kayan 40
Table 4.6: List of Oil Palm Plantations Found in Batang Kayan Catchment 42
Table 4.7: Development Schedule for Tamang Sembawang and Pasir Hilir Oil 45
Palm Plantation
Table 4.8: Development Schedule for Stenggang Oil Palm Estate 46
Table 4.9: Development Schedule of Ray a Oil Palm Plantation 47
Table 4.10: Development Schedule for FELDA Sampadi Plantation Group 48
Table 4.11: Result of the Ranking of Local Perception on the Major Cause of 52
Pollution to Batang Kayan
Table 4.12: Endangered and Rare Species ofFish in Batang Kayan 58
Table 4.13: Water Quality at Batang Kayan, on the 6th November 2003 78
IX
Figure 1.1:
Figure 2.1:
Figure 3.1:
Figure 4.1:
Figure 4.2:
Figure 4.3:
Figure 4.4:
Figure 4.5:
Figure 4.6:
Figure 4.7:
Figure 4.8:
Figure 4.9:
Figure 4.10:
Figure 4.11:
LIST OF FIGURES
Batang Kayan Catchment and its Land Uses 5
Examples of Some Changes of Natural Hydrological Pathways by 8
Anthropogenic Activities
Location of Rainfall and Water Quality Monitoring Stations 19
Total Annual Rainfall and Evaporation in Batang Kayan Catchment 27
(1980 - 2003)
Dailyl Mean Evaporation in Lundu (1983 - 2002)
General Soil types in Batang Kayan Catchment
Agriculture Capability of Batang Kayan Catchment Soil
29
31
35
Land Use and Other Anthropogenic Activities in Batang Kayan 36
Catchment
Batang Kayan Water Quality Index and its Sub-index
Water Quality Index Trend in Selampit Sub-Catchment
Turbidity of Batang Kayan Monitoring Stations
Conductivity of Batang Kayan Monitoring Stations
58
59
61
62
Ammonia Nitrogen Concentration at the Batang Kayan Monitoring 64
Stations
Total Suspended Solids Concentration and Rainfall in Selampit 67
Sub-Catchment
Figure 4.12: Total Dissolved Solids Concentration in Selampit Sub-Catchment 69
Figure 4.13: pH Level at Selampit Sub-Catchment 71
Figure 4.14: DO and BOD Concentrations at Selampit Sub-Catchment 73
Figure 4.15: COD Concentration at Selampit Sub-Catchment 74
x
1.1 Introduction
CHAPTER 1
INTRODUCTION
The major concern of land use changes in Malaysia and other developing countries is the
rapid forest clearance for other land uses particularly for agricultural activities. This
activity of forest clearance is driven by the economic development. The rapid forest
clearance to other land use is not a new practice for human but it has been done hundred
of years back when men clear small area of land to settle and do some agricultural
activities such as planting fruits and vegetables and animal rearing. The difference
between the present generation and the past generation is that nowadays the clearings are
larger and more extensive. Thus, the extensive land conversion from forest to other type
of land use can give significant impacts on water resources.
Kiely (1998) pointed out that among the main concern of pollutants types that are derived
from agriculture activities are nutrients (nitrogen and phosphorus), organic matter (BOD),
pathogens (bacteria), synthetic organic chemicals such as pesticides and in arable areas,
eroded soils. He also stated that although physical dimensions can identify the
agricultural lands, the precise origin of the pollutants from these areas (agricultural lands)
cannot be identified early particularly when these areas are within the water catchment.
This situation whereby the source of pollution is unknown is called non-point sources
pollution (NPS). fu water catchment area, all tributaries meet at the main river.
1
Therefore it is difficult to pinpoint or detenmne the source of the pollution in that main
river.
Excess precipitation (rainwater) is the transport agent ofNPS pollutants to surface waters
by creating the surface runoffs. Runoff from different types of land use carries different
types of pollutants (Tong and Chen, 2002). For example, as mentioned above, runoff
from agriculture area would typically contain nutrients and sediments meanwhile the
runoff from residential area would mostly be enriched with pathogens, organic matter and
nutrients (from detergents). Charbonneau and Kondolf (1993) strongly stressed that NPS
pollution as the most significant source of surface water quality deterioration is directly
related to land use and agriculture is the greater contributor in NPS pollution. This is due
to the fact that in agriculture, soil disturbance and application of fertilizers and pesticides
are done extensively.
To determine how water quality is changing over time is as equally important as to
determine which activities or land uses that affecting the water quality. Moraes et al.
(1998) stated that the knowledge of trends and changing points, their position in time and
if they are statistically significant, is important because they allow the interpretation of its
possible causes. By studying the relationship between water quality and its temporal
behaviour, proper actions for preservation and management of water resource can be
developed.
2
1.2 Study Area
The selected study area is Batang Kayan Basin. It is located in Lundu District and the
area of the basin is 1645 km2 (Department of Irrigation and Drainage, 2002b). The total
combined length of Batang Kayan is 125 km. Among the tributaries that drain into
Batang Kayan are Sungai Temelan, Sungai Pasir, Sungai Snibong, Sungai Bagadin,
Sungai Stungkor and Sungai Butan. However, this study is more focussed on Selampit
sub-catchment.
The main economic activities in Lundu District are agriculture and tourism. Oil palm,
paddy and cocoa are among the main types of crops planted are. Most of the oil palm
plantations and paddy fields are located near the banks of Batang Kayan. The main
agencies that involve in developing Lundu District is Department of Irrigation and
Drainage (DID), Sarawak Economic Development Corporation (SEDC), Land
Consolidation and Development Authority (LCDA), SALCRA, FELDA and some private
plantations. Despite all the extensive and rapid development in Lundu District, the water
quality index for Batang Kayan is generally at Class II at present (Department of
Irrigation and Drainage, 2002c and ASMA, 2003). Figure 1.1 presents the study area and
its land uses.
1.3 Study Objectives
The main objectives ofthis study were
a) To determine the impact ofland use changes on the water quality of Batang Kayan.
3
b) To examine the trend in the water quality status of Batang Kayan particularly the
Selampit sub-catchment from the year 1997 - 2002.
1.4 Significance of Study
Lundu has undergone a lot of development. The development projects such as paddy
plantation use Batang Kayan as the source of water. It goes the same for oil palm
plantations whereby water pumps are installed at the banks of Batang Kayan for watering
purposes and for other uses by plantation workers. Eventually, the used and polluted
water will be discharged back to Batang Kayan whether through irrigation drainage
system or to other Batang Kayan tributaries. Thus, it can be said that Batang Kayan is a
sink to all the pollutants from all the plantations. In view of this fact, there is a need to
closely examine if there is any significant relationship between human-induced changes
and the water quality trend of Batang Kayan.
4
o 5
' " 30' N
SOUTH CHINA SEA
(J
1.
IU,. .. E
tOO'E SElAMPIT SUBC TCHME T
• MAIN BASIN BOUNDARY BTG. KAYAH CATailiENT INTERNATIONAL BORDER ROADS
CJ DID Schemes _ LCOA Projedl
- SEOC Protedl _ SALCM Projedl
CJ PrIvate Planlltloll
110"00' E
1"30' N
Figure 1.1: Batang Kayan Catchment and its Land Uses
Source: Department of irrigation and Drainage (2002b)
5
CHAPTER 2
LITERATURE REVIEW
2.1 Importance of Water Catchment
Water catchment is an area of land bounded by topographic features that drains water to a
shared destination such as lakes, rivers and seas (Berka et al., 1995). It captures
precipitations, filters and stores waters and determines it releases. Since many biological
processes and anthropogenic activities are dependent on water, thus water catchment is
always being used to study the ecological stress. fu addition, as the surface water drains
to one outlet in a water catchment, the land activities upstream affect the water quality
and quantity at any point. Peters and Meybeck (2002) stated that the quality of surface
water at any point in the catchment indicates the cumulative effects of many physical,
chemical, and biological processes that affect water as it flows along hydrologic
pathways over and through the land. fu other words, the chemical properties of water
change when it interacts with any liquids, solids or gases. Peters and Meybeck (2000)
also added that the degradation of water quality in a point of water catchment can have
adverse effects on the users downstream.
Impacts of land use and other anthropogenic activities on hydrologic regime and water
quality are dependent on the size of the catchment (Kiersch, 2000). Thus, it is important
to consider the scale (spatially and temporally) as it can denote whether any land use
practices upstream are affecting the water quality at downstream. Kiersch (2000) added
that in most cases, the impacts on hydrologic regime and water quality (in terms of
6
parameters such as sedimentation load, organic matters and pathogens) can be
substantiated within small catchments. Based on the study of Ganges-Brahmaputra Basin,
Ives and Messerli (1989) stated that anthropogenic impacts on smaller watersheds is more
pronounced as compared to medium and larger watershed size. In watershed of medium
size, it is difficult to determine which impact is caused by natural causes or
anthropogenic activities. Meanwhile, in larger watersheds, impacts from natural causes
are the main factor. Kiersch (2000) has summarised the impacts on water quality due to
human activities in Table 2.1. However, in reality, this is cannot be applied to all water
catchments. There are few scenarios where Kiersch's theory cannot be applied. For
example, a small catchment that is under developed may have insignificant impacts.
Likewise, a large water catchment that is highly developed may have very significant
impacts.
Table 2.1: Spatial Dimensions of the Impacts of Human Activities
Watershed size (kmz) Impacts 0.1 1 10 lOz 103 104 105
Sediment load x x x x Nutrients x x x x x Organic matter x x x x Pathogens x x x Salinity x x x x x x x Pesticides x x x x x x x Heavy metals x x x x x x x Thermal x x
x ()bservable impact No observable impact
7
2.2 Human Effects on Water Quality
Man-induced activities have direct impacts on hydrologic cycle by altering the land in
ways that change its physical, chemical and biological properties (peters and Meybeck,
2000). Physical changes such as urbanisation, transportation, irrigation, deforestation and
forestation, land drainage, channelisation and damming, and mining change the
hydrologic pathways and thus, may change the water quality properties by modifying the
materials with which the water interacts (see Figure 2.1).
Pre·development
Modern day (~_teru6e.)
Figure 2.1: Examples of Some Changes of Natural Hydrological Pathways by Anthropogenic Activities
(Source: Peters and Meybeck, 2000)
Other than that, human activities such as irrigation, landfills and mine tailings may also
add substances and wastes (for example pesticides, herbicides and fertilisers) to the
landscape and this changes the land chemically. Chemical changes that associated with
anthropogenic activities are partially related to physical changes but happens mainly
8
through the addition of wastes (gases, liquids, and solids) and other substances to the land
(peters and Meybeck, 2000). Some of these wastes and substance are released directly to
the surface water (point sources) and some are distributed over a larger area (non-point
sources). According to Peters and Meybeck, biological changes include forest
management, agriculture, and the import of exotic species.
In Malaysia and other South East Asian countries, land use and land cover is a major
concern whereby forests are being converted to other land uses and agricultural lands are
also being altered to urban areas, both in a very fast pace (Syarifah, 2000). The land use
and cover changes have resulted in severe erosion, sedimentation and other water
pollution problem in water catchments particularly in downstream. In fact, according to
Falkenmark and Chapman (1989), streams from logged areas in Malaysia carry 8 to 17
times more sediment load as compared to before logging.
2.3 Sources of Water Pollution
Chhatwal et al. (1993), defined water pollution as the addition to water of an excess of
material (or heat) that is harmful to humans, animals, or desirable aquatic life, or
otherwise causes significant departures from the normal activities of various living
communities in or near water bodies. Generally, the sources of pollution are divided into
two categories namely point sources and non-point sources.
Point sources pollution is type of pollution that derived from human activities whereby
pollutants such as wastewater is directly released into receiving water body (Ibrahim,
9
2000; Ongley, 1996). However, according to US-EPA (as cited by Ongley, 1996),
pollutants runoffs from agriculture activities are not considered as point sources.
Ongley (1996) has clearly defines non-point sources pollution as pollution that sources
originated from a wide group of human activities for which the pollutants have no
obvious point of entry into receiving waterways. Each activity within the water
catchment may contribute to non-point sources pollution. Table 2.2 denotes the classes of
non-point sources pollution.
Table 2.2: Classes of Non-Point Source Pollution
Land Use Pollution Source Major Pollutants Agriculture Runoff from all categories of agriculture leading to Phosphorus,
Animal surface and groundwater pollution. Vegetable nitrogen, metals, feedlots handling especially washing in polluted surface pathogens, sediment, Irrigation waters in many developing countries, leads to pesticides, salt, Cultivation contamination of food supplies. Growth in BOD, trace elements Pastures aquaculture is becoming a major polluting activity (e.g. selenium). Dairy farming in many countries. Irrigation return flows carry Orchards • salts, nutrients and pesticides. The drainage rapidly Aquaculture carries leachates such as nitrogen to surface waters.
Forestry Increase runoff from disturbed land. Most damaging Sediment, pesticides. is forest clearing for urbanisation.
Liquid waste Disposal of liquid wastes from the municipal Pathogens, metals, disposal wastewater effluents, sewage sludge, industrial organic compounds
effluents and sludges, wastewater from home septic • systems; especially disposal on agricultural land and
legal and illegal dumping in the water catchments. Urban areas Urban runoff from roofs, streets, parking lots, etc. Fertilisers, greases
Residential leading to overloading of sewage plants from and oils, faecal Commercial combined sewers, or polluted runoff routed directly matter and Industrial to receiving waters; local industries and businesses pathogens, organic
may discharge wastes to street gutters and storm contaminants, heavy drain; street cleaning; road salting contributes to metals, pesticides, surface and groundwater pollution. nutrients, sediments,
salts, BOD, COD,
I
etc.
10
Rural sewage Overloading and malfunction of septic systems Phosphorus, systems leading to surface runoff and/or direct infiltration to nitrogen, pathogens
ground water. (faecal matter). Transportation Roads, railways, pipelines, hydro-electric corridors, Nutrients, sediments,
etc. metals, organic contaminants, pesticides (especially herbicides).
Mineral extraction Runoff from mines and mine wastes, quarries, well Sediment, acids, sites. metals, oils, organic
contaminants, salts (brine).
Recreational land Large variety of recreational land uses, including Nutrients, pesticides, use boating and marinas, campgrounds, parks; waste sediment, pathogens,
and 'grey' water from recreational boats is a major heavy metals. pollutant, especially in small lakes and rivers. Hunting (lead pollution in waterfowl).
Solid waste Contamination of surface and groundwater by Nutrients, metals, disposal leachates and gases. Hazardous wastes may be pathogens, organic
disposed of through underground disposal. contaminants.
Dredging Dispersion of contaminated sediments, leakage from Metals, organic containment areas. contaminants.
Deep well disposal Contamination of groundwater by deep well Salts, heavy metals, injection of liquid wastes, especially oilfield brines orgamc and liquid industrial wastes. contaminants.
Atmospheric Long-range transport of atmospheric pollutants Nutrients, metals, deposition (LRTAP) and deposition ofland and water surfaces. organic
Regarded as a significant source of pesticides (from contaminants. agriculture, etc.), nutrients, metals, etc., especially in pristine environments.
(Source: Ongley, 1996)
In many types of land use activities, non-point source pollution is dominantly attributed
by agricultural activities due to its large extend of area, extensive soil disturbance and
application of fertilisers and pesticides (Charbonneau and Kondolf, 1993). In addition to
that, Charbonneau and Kondolf (1993) also asserted that suspended sediment as the
11
largest surface water non-point source pollutant (on a volumetric basis) and nutrients
come next. Sediments affecting the water quality in two main ways (Ibrahim, 2000;
Ongley, 1996):
• High levels of turbidity impede sunlight penetration into the water column;
subsequently hinder the growth of algae, and rooted aquatic plants. In spawning
rivers, gravel beds are covered with fine sediment that hampers spawning of fish.
Both ways can disrupt the aquatic ecosystem by destroying the habitat.
• High levels of sedimentation in rivers contribute to physical disruption of the
hydraulic characteristics of the river channel. This can cause problem in
navigating due to the reduction of the depth of the channel. Sedimentation can
also cause flooding events to increase by the reductions in capacity of the river
channel to efficiently route the water through the drainage basin.
Meanwhile high concentration of nutrients can lead to nuisance growth of aquatic weeds
and algal blooms. According to Kiersch (2000), high nutrient leaching losses can occur
when fertiliser is applied to short-term crops on permeable soils. As the plants die, they
contribute to the organic loading and cause organic pollution. This process of increased
plant growth and decay, the increased activity of the decomposing microorganisms, and
the depletion of dissolved oxygen, is called eutrophication (Ibrahim, 2000).
Activities such as irrigation and drainage may cause salinity of surface and groundwater
to increase. This is due to the evaporation and the leaching of salts from soils (Kiersch,
12
2000). Besides that, Postel (1997) added that drainage from irrigated agriCUlture might
also cause selenium concentration in both surface and groundwater to increase.
Ibrahim (2000) approximated that the designation of pollutant input sources may be
based on land use. This is due the fact that land use change the drainage characteristics of
the land and the activities carried out result in new pollutants being emitted. The intensity
of drainage characteristics alteration depends on the intensity of the extend of
urbanisation. Generally, the amount of runoff and the speed of runoff flow will increase
with the intensity of urbanisation and drainage characteristics alteration. This reduces
infiltration and retention of water over the ground, and with the increase of flow, the
pollution carrying capacity is also increased.
In addition to drainage alterations, the type of activity carried out will also affect
pollutant inputs. The higher intensity of activity level is, the higher the possibility of
pollutants being emitted to watercourse. Different activities are associated with different
types of pollutants. Depending on the nature of the pollutants, some may degrade in the
environment naturally and some may persist for long period (Ibrahim, 2000).
2.4 Case Studies on the Relation orLand Use and Water Quality
A number of similar studies were conducted both locally and internationally. Almost all
conclude that land use or anthropogenic activities do result in water quality deterioration.
13
