INTRODUCTION AND OBJECTIVE

Transcription

1 Chapter 1 INTRODUCTION AND OBJECTIVE 1.1 INTRODUCTION Of all environmental issues, pollution must surely be of major importance in terms of its impact on people s health and their living and working environments. Pollution is the result of the changes in the environment. These changes are due to human socioeconomic activities that bring negative effect to humans and other living things around them. Harrison (1990), defines pollution as waste that is harmful to other organisms or to the waste producer. According to the Chambers Dictionary (1992), pollution may be defined as the rendition of any feature of the environment offensive or harmful to human, animal or plant life. From the human perspective, what is considered to be pollution in a fluvial system depends largely on the use of the river. For example, rivers which are designated fisheries may be polluted if substances discharged into the river damages fish stocks, although no nuisance or health hazard is presented to the human population. To an angler, the deposition of autumn leaves into streams may be considered pollution, whereas to an ecologist it is viewed simply as a natural occurrence. The public associates river pollution with offensive odours and discolouration, although potential harm to human health may be present in apparently clean water. 1

2 River pollution can be caused by several effluents and their effects are of great concern to health. Disposal of waste water generated from municipal and industrial sources with little or no treatment prior to discharge is a common practice in many developing countries including Malaysia. This practice has been continuing over the history of civilization and as a result of population growth and increasing industrialization, serious problem of the water quality are commonplace. Rivers play a major role in assimilating or carrying off industrial and municipal wastewater, manure discharges and runoff from agricultural fields, roadways and streets, which are responsible for river pollution (Ward and Elliot, 1995). During , the average annual urbanization rate in developing countries were over 3.4% compared to only 0.7% in developed countries (UN 1996). In the water sector, this can cause two types of impacts: high demand for freshwater and serious pollution of the available water resources. According to the Asian Development Bank (ADB) (1997), water pollution and freshwater depletion are currently viewed as the top environmental problem in Asia. Karn and Harada (2001) showed that in the South Asian Region, specifically in Nepal, Bangladesh and India, pollution of surface waters has become more severe and critical near the urban areas due to high pollution loads discharged within short stretches of rivers from urban activities. In a recent literature, up to 450 chemical compounds have been identified as important in water quality problems. With time, more and more of them will be identified, since the industrial societies will continue to develop and synthesize new chemicals each year (Sanders et al., 1983). As the number of chemical compounds increases, more chemicals may migrate into the water environment. 2

3 The composition of natural river water depends upon the nature of the surrounding catchment area and its interaction with precipitation. In brief, rainfall incidents on a catchment may first be intercepted by foliage, and lost to the atmosphere by subsequent evapotranspiration, or water that lands on steep slopes may directly run off into the drainage network. Water that encounters ground that possesses a soil moisture deficit may be soaked in, and may eventually reach the river via soil interflow or groundwater recharge. Pollutants may enter the river system through an effluent discharge, accidental spill or combined sewers overflow (point sources) or via contamination of rainfall runoff which is due to land use surrounding the catchment area, atmospheric deposition or groundwater seepage (diffuse sources). Once in the river channel, they may be carried downstream, either in suspension or dissolved in the water, or alternatively they may sink and settle in the bed sediments. They may at any time be taken up as food or adsorbed into the flesh of aquatic organisms. The processes that contribute to river pollution are numerous and varied, complicated by many factors. 1.2 River pollution in the Malaysian perspective Peninsular Malaysia, in particular the State of Selangor, has a long history of river pollution problems related principally to land use changes. The Langat River is one of the principal river draining a densely populated and developed area of Selangor. Over the past 40 years, it has served about half of the population of Selangor and is a source of 3

4 hydropower and control of flood discharges. More than two third of the Selangor population inhabit the floodplain which provides highly fertile land for agriculture, land for housing, recreation and industrial developments. This scenario has brought humans into conflict of harmony with the river environment, and increases the degree of pollution into river channels. According to Environmental Section (1977) 42 tributaries in Peninsular Malaysia has been categorized as very polluted including the Langat River. Until 1999, there were about 13 polluted tributaries all over Malaysia with 36 polluted rivers due to human activities such as industry, construction and agriculture at the tributaries (DOE, 1999). In 1990, there were 48 clean rivers compared to only 32 rivers in 1999 that could still be classified as clean (Rosnani Ibrahim, 2001). In Malaysia, almost 60 percent of its major rivers are regulated for domestic, agricultural and industrial purposes (DID, 2001). According to Rosnani Ibrahim (2001), the major pollution sources of concern affecting Malaysian rivers are sewage disposal, discharges from small and medium-sized industries that are still not equipped with proper effluent treatment facilities and land clearing and earthworks activities. Based on the year 1999 records, 50 river basins (42% of river) were polluted with suspended solids (SS) resulting from poorly planned and uncontrolled land clearing activities; 36 river basins (30% of river) were polluted with biochemical oxygen demand (BOD) resulting from industrial discharges and 33 river basins (28% of river) with ammoniacal nitrogen (AN) from animal husbandry activities and domestic sewage disposal. 4

5 The Langat River catchment straddles the main urban conurbation in the Klang Valley forming parts of the growing urban complex of the Selangor State. Since 1970 urban expansion has occurred in the Langat River catchment, including extensive land conversion from agriculture use to urban-industrial-commercial landscape. According to Verburg et al. (2004), the changes of land use and land cover are particularly related to increase of population and intensive agriculture. From the government census reports of 1970, 1980 and 1981, Selangor is one of the most populated states in Malaysia that has recorded a rapid growth from a total of less than one million in the 1970 Population Census, to 1.4 million in 1980 to close to 2.3 million in the 1991 Census. It has been estimated that the population in 1998/1999 was around 3.1 million people (Abdul Hadi and Samad, 2000). Based on the inventory list from Department of Environment of the State of Selangor, there were 693 potential sources of pollutant at the Langat River Basin. The main sectors which form the major contribution of pollution loading are shown in Figure

6 Industries Sewage Treatment Plant Pig Farm EIA Projects Figure 1.1: Pie chart the of the main sectors that contribute to the pollution loading into the Langat River Basin. Langat River as a source of drinking water supplies a part of Kuala Lumpur (Federal Territory) and State of Selangor via eight water treatment plants. Langat River is also an important water resource to industrial activities and aquaculture projects located at the downstream areas. Due to the fact that the Langat river continues to be polluted, being the most important water source for Kuala Lumpur and a large part of the state of Selangor, DOE have initiated programs to stop pollution and increase the water quality of the river. One of the programs initiated was the Langat River Pollution Prevention and Water Quality Improvement Program The main objectives of the program are as follows: i. To improve and increase the water quality of the Langat River Basin which have been categorized as polluted or partly polluted. 6

7 ii. To change the water quality of the Langat River from classes III and IV to class II which is suitable to be used as drinking water with conventional water treatment. iii. To revive and maintain on overall status of the Langat Basin of class II after the project has ended. One of the important tools to ensure success of the program is water quality modeling. Water quality analysis and modeling is important in providing decision makers the basis for making correct policies that would be effective in reading the objectives of the program. 1.3 River Water Quality Analysis and Modeling Increasing concern over river quality worldwide, coupled with improved monitoring technology, led to the introduction of stricter legislative measures to control the discharge of polluting loads. In order to satisfy these new criteria without excessive expenditure on over-treatment, a method is needed to optimize the control of the treatment process. Knowledge of the expected quality and quantity of the receiving water at the time of effluent release can be combined with knowledge of the characteristics of the untreated effluent to predict the level of treatment that will result in a minimal impact on the receiving environment. 7

8 Water quality modeling is a very useful procedure in many planning and operational aspects of the water industry, and a number of models have been developed to predict river quality and the impacts of potential affluent discharges due to land use changes. Although the research carried out is relatively unsophisticated and is hampered by a general lack of data compared to western countries, there has been an increasing impetus towards using models to study river catchment issues in Malaysia. Wide range of techniques available have extended opportunities to study river water quality related to land use change in greater detail and on a wider spatial and temporal scale. This particular study aims to expand the knowledge base in relation to the dynamics of river systems within Peninsular Malaysia, and in particular aims to concentrate on the nature and causes of river water quality changes. 1.4 Research Aims and Objectives The overall aim of this study is to investigate both the historic and contemporary river quality change across different land classes within the Langat River system. As described above, this research concentrates on the Langat River in Selangor where the dynamics of river water quality are significantly altered due to land use change and other environmental forces. This research has several key objectives: 8

9 1. To analyze and evaluate spatial and temporal variations based on historical data of land use and river water quality data using envirometric methods. 2. Development of the land use cumulative index (LUCI) to represent the land use cumulative pollution loading along the main river from upstream to downstream as an input parameter to improve the prediction of river water quality. 3. To assess the influence of pollution and seasonality on the quality of Langat River water using multivariate analysis 4. Development and structuring of spatial and temporal data for artificial neural network (ANN) learning process. The ANN models would enable us to relate how the various land use pattern affects water quality. 1.5 Thesis Outline The first three chapters in the thesis aim to provide the background to the various subject areas related to the research. Chapter 1 identifies the aims and objectives of the research. Chapter 2 presents the literature review of perspectives and initiatives for integrated water resources or river management and the role of modeling. It focusses on the nature of change and water quality modeling as well as forecasting with artificial neural network. Chapter 3 discusses the general setting of the Peninsular Malaysia, and includes a detailed description of the physical environment of Langat River catchment, by 9

10 describing the location, the catchment morphometry, geology, topography, climate, soil and present land use. Chapter 4 evaluates the spatial and temporal aspect of land use changes within the Langat River. In this chapter, maps and aerial photography related to the study reaches are examined. GIS-ArcInfo was used to study the land use changes at the 15 sub-basins of the Langat River Basin. The spatial land use change trends were thoroughly examined as the basis for the development of LUCI in Chapter 5. Chapter 5 discusses the important factors of the water quality change. In this chapter, a detailed temporal examination of water quality change (<10 years time span) was carried out. This chapter also examines the water quality change due to land use changes based on the historical-gis map-aerial photograph analyses carried out in Chapter 4. This chapter also discusses in detail the quantitative analysis applied in determining the best water quality parameters representative of the land use change within Langat River Basin. Finally, the development of LUCI as well as its relationship with water quality of Langat River are discussed. Chapter 6 provides a qualitative and quantitative analyses of the development of the ANN prediction models. Several techniques were employed in this chapter to identify the best set of input parameter for the ANNs. These include discriminant analysis (DA) and sensitivity analysis. In this chapter, five different ANN models were developed with 10

11 various input and output schemes. This chapter also investigates the best performing ANN network structures with optimum number of inputs and minimal loss of information. Chapter 7 provides an overall conclusion of the thesis. Figure 1.2 shows the flow of the thesis from Chapter 1 to Chapter 7. 11

12 Chapter 1: Introduction Chapter 2: Malaysian River Management Chapter 3: Description of Langat River Basin Chapter 4 Data Collection Chapter 5. Land Use Analysis 1. Reclassification of all land use types to 5 general types 2. Computation of areas for the Langat catchment areas as well as areas within 1, 2 and 3 km away from the main river for each land use types 3. Computation of SDI values Data Preprocessing Water QualityAnalysis 1. Sorting of data 2. Rearrangement of data 3. Handling of missing data Classification of each sub-basin using SDI based on the DOE monitoring stations along the river Exploratory Data Analysis 1. Descriptive Statistics 2. Trend Analysis 3. Envirometric Methods a. HACA b. DA c. PCA/FA Classification of subbasin using water quality parameter based on the DOE monitoring stations The development of Land Use Cumulative Index (LUCI) Input/output selection parameter Chapter 6: ANN model development Chapter 7: Conclusion Figure 1.2: Summary of the thesis 12