WATER QUALITY MODELING OF KUYOH RIVER BASIN, MALAYSIA

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1 WATER QUALITY MODELING OF KUYOH RIVER BASIN, MALAYSIA NORBAYA HASHIM (1), FANG YENN TEO (1) (1): National Hydraulic Research Institute of Malaysia, Malaysia ABSTRACT River pollution which is a type of man-made water issue in Malaysia and other countries of the world has been worsened over the years. The main objective of this paper is to develop a river hydrodynamic model covering the main area of the Kuyoh River, and then followed by the development of water quality model. The important input parameters of the proposed model are the data of river cross section, river discharge, water quality, landuse and several other relevant activities in the river basin. GIS interface was applied in analyses of landuse activities as well as in estimating discharges that were generated. The tributaries were modelled as pollution inputs. Calibrations were carried out at upstream and midstream portions of the river. The trend of pollution from model simulation was then compared with observed data. An analysis of water quality parameters to examine the extent of pollution was carried out. The results of the simulations with some degree of water quality improvement for the river tributaries of Anak Kuyoh river and Jinma river have resulted in improvement of the overall water quality. The water quality model is found to be a useful tool in assisting decision makers to plan and implement effectively the infrastructure and physical development projects within the Kuyoh River basin. Keywords: river pollution; hydrodynamic modeling; water quality modeling 1 INTRODUCTION Kuyoh River is one of 11 tributaries of Klang River. The water quality of Kuyoh River system has been deteriorating over the years, which have been classified as a polluted river (Class III & IV) by the Department of Environment, Malaysia [1]. This catchment area has undergone rapid development since the early 1990s, which has resulted in an added strain on the Klang River and its many tributaries. This research has been carried out to develop a rehabilitation solution for Kuyoh River by using the technique of numerical modeling. Kuyoh River catchment is located within the state of Selangor and Federal Territories of Kuala Lumpur. Kuyoh River is a tributary of Klang River covers an area of 83 sq. km with 12.5 km length of a major river (Figure 1). The tributaries of Kuyoh River are: Anak Sungai Kuyoh, Sungai Jinma, Sungai Pati Liat, Sungai Midah, Sungai Rekah and Sungai Bohol completes the entire catchment area and connect to the lower Klang River basin. However, only 8.4 km of the main river has been selected which is from upstream at Universiti Putra Malaysia, Serdang down to the National Sport Complex, Bukit Jalil for this study and covering three sub tributaries namely Anak Sungai Kuyoh, Sungai Jimna and Sungai Pati Liat (Figure 2). A large portion of the catchments is made up mainly of residential, agriculture and industrial area (Figure 3). The total population within the catchments studied is approximately 78,000 (Sources: Statistic Department of Malaysia, 2000) [2]. The objectives of this study are: (i) to investigate the source of pollution and the loading discharging into the river, (ii) to understand the behavior of the pollutant movement by using water quality model, and (iii) to predict the Water Quality Index (WQI) for specific parameters. This study involved field measurements, data collection and development of water quality model, which include hydraulic and water quality simulation. The water quality model shall be able to describe the present situation, predict future trend and identify the major pollution sources. 2 DATA COLLECTION/ FIELD MEASUREMENT River cross section data is the main input to develop the hydraulic model. The survey work of river cross section was done in 2007 and some portion of river survey was obtained from the Department of Irrigation and Drainage, Malaysia [3]. The land use GIS layer was developed by using SPOT 5 satellite images taken in Site inspections were also carried out to confirm the land use development pattern. River and road data layer were obtained from the Department of Survey and Mapping, Malaysia. Proceedings of the 7 th International Symposium on Environmental Hydraulics Copyright 2014 ISEH VII Organisers. All rights reserved. ISBN:

2 Figure 1: Location of Study Area Figure 2: Sg. Kuyoh subcatchment Figure 3: Landuse map of study area (2006) Field work has been carried out two times together with flow measurement and water quality sampling. The samples collected covering a wide range of catchments and surface water types (rivers and tributaries) during dry period. First sampling was carried out on 7 and 8th January 2008 during dry period. The samples are collected continously 24 hours at 4 selected location with a total of 24 samples and 18 parameters. The data will be used for the purpose of hydrodynamic model calibration. The second times of sampling was conducted on 31st May to 7th June These samplings were carried out over a period of 4 days. Grab samples were taken at discharge points and drains depending on the sampling sites. Points 1 to 17 were sampled at outlet just before flowing into the main drain or river. The data will be used as input in water quality model. While data at Points 18 to19 were taken in the river and will be used for water quality calibration. 3 NUMERICAL MODELING A one-dimensional hydrodynamic model which deployed the full St. Venant equation was used to study the behaviour of the pollution process in the river system. The modeling process involves two phases, namely the flow model and the water quality model [4]. The model is capable of analysing unsteady flow in the river. The river model covers for the main river and major tributaries of Kuyoh River subcatchment. The main data inputs are the river cross sections, details of hydraulic structure along the river such as weirs, discharge and water quality data. Calibration of hydrodynamic model has been made from estimating base flow and wastewater that discharge out from the areas of residential, commercial, educational and industrial, where the study is focus on pollution during dry season. This estimation was later compared with the observed data (Table 1). Calibration on hydrodynamic model was carried out based on observed event on 7 and 8th January The input to water quality models is the river water quality data. The data taken at tributaries and drainage system will be used as input to the model while data in the river will be used as a comparison for calibration. In this study only 2 parameters will be compared during calibration process which is DO and BOD. The parameter 196

3 was selected due to the dominant pollutants in Sungai Kuyoh subcatchment that give a low water quality reading of DO and high BOD. Calibration on water quality model was carried out based on observed event on 31st May to 7th June It is assumed the data on dry weather will have a similar pattern at any time of the same season. Calibration of DO and BOD has been made at 2 points in the river which is at Kuyoh 10500/ Point 19 (midstream) and Kuyoh 5800/ Point 18 (downstream). Tables 2 and 3 shown the percentage different between observed and simulated DO and BOD respectively. Table 1: Comparison between estimated flow and observation Zone Name Estimated Observation Difference Flow (m 3 /s) Flow (m 3 /s) 1 Sungai Kuyoh U/S Anak Sungai Kuyoh Sungai Kuyoh Sungai Patiliat Sungai Jinma Sungai Kuyoh D/S Zone ID Percentage of Diff. (%) Table 2: Percentages different between observed and simulated DO Location Simulated (mg/l) Observed (mg/l) Difference Percentage of Diff. (%) Kuyoh 10500/ Pt 19 (midstream) Kuyoh 5800/ Pt 18 (downstream) Table 3: Percentages different between observed and simulated BOD Location Simulated (mg/l) Observed (mg/l) Difference Percentage of Diff. (%) Kuyoh 10500/ Pt 19 (midstream) Kuyoh 5800/ Pt 18 (downstream) RESULTS AND DISCUSSION Preliminary analysis base on the existing condition was simulated. Three locations have been selected along the Kuyoh River for the purpose of water quality analysis.the analysis was carried out based on the zoning distribution and the existing condition was set as a benchmark as a comparison to the propose measures. The analysis focuses on the quantity of pollution i.e. depending on selected parameter. The selections of zone to be prioritized are done by testing each individual pollution measure at each zone. Assumption has been made that all the scenarios tested in modeling is based on assumption that the release from the source should meet Class II requirement. Figure 4-Figure 9 shows the impact of improving DO and BOD at 3 analysis points. For the first analysis point at the upstream of Kuyoh River and the confluence of Anak Sungai Kuyoh, the water quality is very much influence from the pollution discharge from Zone 1 and Zone 2 and Zone 3. The existing DO reading along this location is under Class IV. The results indicate that more than 90% of the time, the river is in Class IV which means the river does not have any assimilative capacity under current situation. From Figure 4- Figure 6, improvement in Zone 2 shows a big significant improvement at the upstream of Kuyoh River. The DO increased from 2 mg/l to above 3 mg/l. The BOD also decreased from 20 mg/l to below 10 mg/l (Figure 7- Figure 9). The second analysis point is located after the Sungai Patiliat confluence, at the midstream of Kuyuh River. The location is very much influence by Zone 1, Zone 2, Zone 3, Zone 4 and Zone 5. If individual zone is treated separately, an improvement at Anak Sungai Kuyoh (Zone 2) has shown a significant changes of DO and BOD reading along the river (see Figures 4- Figure 9). The improvement option followed by Zone 5 (Sungai Jinma) and Zone 1 (Sungai Kuyoh upstream). Another 2 zones (Zone 3 & 4) showed small significant effects towards DO and BOD readings in the river. The third analysis point is located at the downstream of the river at Kuyoh This location is influenced by all zone involved which is Zone 1, Zone 2, Zone 3, Zone 4 and Zone 5. The analysis result give almost the same impact as Analysis Point 2 but some of the time, the river in the downstream will change from Class III into Class II. The DO increased from 3 mg/l to above 4 mg/l. The BOD also decreased from 18 mg/l to below 13 mg/l (Figure 4- Figure 9). 197

4 Figure 4: DO impact at Analysis Point 1 by improving Figure 5: DO impact at Analysis Point 2 by improving Figure 6: DO impact at Analysis Point 3 by improving Figure 7: BOD impact at Analysis Point 1 by Figure 8: BOD impact at Analysis Point 2 by Figure 9: BOD impact at Analysis Point 3 by Zone 2 (Anak Sungai Kuyoh) is proposed for the first implementation to be improve since it is at the most upstream in the catchment as well as the highest contributors load for BOD and COD. Improvement of this zone will immediately improve the river at the midstream of Kuyoh River (before the Analysis Point 2). Next improvement need to be implement is at Zone 5 (Sungai Jinma). Improving this zone will enhance the river improvement in the midstream. However, if improvement taken for both Zone 2 and 5, the river shall meet Class III at the downstream. CONCLUSION The using of water quality model to understand pollution behaviour is a best approach in river basin management. The water quality model that was developed in this study was found to be a useful tool in assisting decision makers in important government agencies of Ministry of Natural Resources and Environment, Ministry of Housing and Local Government such as the local authorities, to plan and implement effectively the infrastructure and physical development projects within the Kuyoh River basin. ACKNOWLEDGEMENT The authors are grateful to the Government of Malaysia for their consent and continuing support for this study. The authors would also like to express their gratitude to all parties involved throughout the study. 198

5 REFERENCES [1] Department of Environment Malaysia (DOE) Malaysia Environmental Quality Report [2] Jabatan Perangkaan Malaysia Taburan Penduduk Mengikut Kawasan Pihak Berkuasa Tempatan dan Mukim. Banci Penduduk dan Perumahan Malaysia [3] Department of Irrigation & Drainage (DID) Final Report: Stormwater Management and Drainage Master Plan Study for the town of Sungai Besi, Kuala Lumpur and Seri Kembangan, Selangor. 199