Mohammad Sholichin Faridah Othman Shatira Akib University of Malaya & Brawijaya University 2006

1. Evaluating and Estimating the Effect ofLand use Changed on Water Quality at Selorejo Reservoir, Indonesia Mohammad Sholichin Faridah Othman ShatiraAkib University of Malaya & Brawijaya University 2006

2. Selorejo Reservoir

3. Scheme • Introduction • Methodology • Results • Conclusion

4. Introduction . Recently, Non Point Sources (NPS) pollution has become the focus of water quality and watershed management. Nitrogen and phosphorous are the two nutrients originating from inorganic and organic fertilizer that affect the reservoir water quality due to intensive agricultural farming. High existence of Nitrogen (N) and Phosphorus (P) in the Selorejo Reservoir indicates the problem in the water quality of the reservoir.

5. Objectives The objectives of this study are : • To identify the sources of pollutants from agricultural and urban area • To apply the Soil and Water Assessment Tool Model (SWAT) • To evaluate the present reservoir water quality status • To predict the reservoir water quality which may change the land use scenario in future

6. Study Area • Brantas River is located in East Java Province on the Java Island, Indonesia • It is the second biggest river in Java Island that has a watershed of about 11,800 km2 and stretches about 320 km • Brantas is divided into six sub basins : 1. Lesti River (625 km2), 2. Konto River (687 km2) 3. Widas River (1,539 km2), 4. Upstream Brantas River (6,719 km2), 5. Ngorowo River (1600 km2) and 6. Surabaya River (631 km2)

8. Brantas River Basin Map Selorejo watershed

9. Konto River Basin • The study area is Selorejo Reservoir that located at upstream of Konto River Basin. • Selorejo watershed has a Catchment area of 235 km2 • The maximum reservoir capacity is 62.30 Mm3, with an effective reservoir capacity of 50.10 Mm3

10. The function of Selorejo Reservoir • Water Supply • Water irrigation • Hydro power • Tourism

11. Selorejo Watershed & Sub-basin 1 2 3 4

12. Land use in Selorejo Watershed

13. Soil Type in Selorejo Watershed

14. Methodology • Pre field-work (literature review, data gathering etc) • Field-work (site visit, water samples on stream and reservoir, etc) • Modeling & Simulation ( set up model, input data, calibration, etc)

15. SWAT (Soil and Water Assessment Tool) The SWAT model was developed by the Agricultural Research Service-US Department of Agriculture. The model predicts the impact of land management of practices on: - water - sediment - agricultural chemical yields For use on large, complex watersheds with varying soils, land use, and management conditions over long periods of time

16. SWAT Input Data • Digital topography map • Land use (land cover) • Soil type • Precipitation-temperature • Discharge • Fertilizer-pesticide • Tillage • Urban area • Stream water quality • Pond/reservoir data • Ground water • Soil chemical data • Water use • Water Management

18. Schematic of input and outputs of the SWAT model

19. Land use change scenario 2000 2005

20. 2005 2010

21. Discharge Calibration Period 2000-2001

22. Results Result of SWAT simulation was divided into three phases, Land Area Reservoir Stream

23. Land Area The average monthly surface runoff for 2000, 2005 and 2010

24. Average Monthly N Organic (kg N/ha) SUB Basin 3 2 0.800 0.700 0.600 0.500 Organic N (kg N/ha) 0.400 0.300 0.200 0.100 0.000 Jan Feb Mar Aprl Mei Jun Jul agst Sept Oktb Nov Dec Month 2000 2005 2010 Average Organic N (kg/ha) 1 3 4

25. Monthly P Organic (kg P/ha) SUB Basin 3 0.160 0.140 0.120 0.100 Organic P (kg P/ha) 0.080 0.060 0.040 0.020 0.000 Jan Feb Mar Aprl Mei Jun Jul agst Sept Oktb Nov Dec Month 2000 2005 2010 Average Organic P (kg/ha)

26. Average Monthly Organic N Transported With Water Into Reach The Sub Basin 1 1.00 0.90 0.80 0.70 0.60 Organic N (g/lt) 0.50 0.40 0.30 0.20 0.10 0.00 Jan Feb Mar Aprl Mey Jun Jul Agst sept Oktbr Nov Dec Month Stream organic n 2000 organic n 2005 organic N 2010

27. Nitrogen Average Monthly Organic N Transported With Water Into ReachThe Sub Basin 4 0.80 0.70 0.60 0.50 Organic N (g/lt) 0.40 0.30 0.20 0.10 0.00 Jan Feb Mar Aprl Mey Jun Jul Agst sept Oktbr Nov Dec Month organic n 2005 organic n 2000 organic N 2010

28. Average Monthly Organic P Transported With Water Into ReachThe Sub Basin 1 Outlet 0.20 0.18 0.16 0.14 0.12 Organic P (g/lt) 0.10 0.08 0.06 0.04 0.02 0.00 Jan Feb Mar Aprl Mey Jun Jul Agst sept Oktbr Nov Dec Month organic P 2000 organic P 2005 organic P 2010 Phosphorous

29. Reservoir Comparison of annual Nitrogen concentration from 2000-2005

30. Correlation between simulation and measurement R2=0,61

31. Phosphorous Comparison of annual P concentration from 2000-2005

32. Correlation between simulation and measurement (R2 =0,78)

33. Conclusion • Available data land use from 2000-2005 and forecast data from 2005-2010 was used to evaluate and estimate the changes of water quality of Selorejo Reservoir • SWAT model has been applied to evaluate and estimate the Selorejo reservoir • The simulation result was found to be under estimated • The change of land use may not have the direct and significant effect to the drop of water quality • Further study on other parameters is required to determine the causes of the drop of water quality in Selorejo Reservoir

34. Acknowledgement • We would like to thank you the following for making this study possible • Department of Agriculture, Indonesia • Department of Surveying, Indonesia • East Java local authority • University of Malaya, Malaysia • Brawijaya University, Indonesia

35. YOU T H A N K