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

2. 2 Selorejo Reservoir

3. 3 MethodologyMethodologyMethodology ResultsResultsResults Scheme IntroductionIntroductionIntroduction ConclusionConclusionConclusion

4. 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 High existence of Nitrogen (N) and Phosphorus (P) in the Selorejo Reservoir indicates the problem in the water quality of the reservoir.

5. 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. 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 km 2 ), 2. Konto River (687 km 2 ) 3. Widas River (1,539 km 2 ), 4. Upstream Brantas River (6,719 km 2 ), 5. Ngorowo River (1600 km 2 ) and 6. Surabaya River (631 km 2 )

7. 7

8. 8 Brantas River Basin Map Selorejo watershed

9. 9 Konto River Basin The study area is Selorejo Reservoir that located at upstream of 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 km 2Selorejo watershed has a Catchment area of 235 km 2 The maximum reservoir capacity is 62.30 Mm 3, with an effective reservoir capacity of 50.10 Mm 3The maximum reservoir capacity is 62.30 Mm 3, with an effective reservoir capacity of 50.10 Mm 3

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

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

12. 12 Land use in Selorejo Watershed Land use2000 Urban Area20.64 Forest92.66 Dry Field36.35 Mixed – Dry Field30.01 Rice Field55.51 Total (km 2 )235.17

13. 13 Soil Type in Selorejo Watershed Soil TypeArea (km 2 ) % Regosol 16.416.976 Grumosol 164.3169.869 Mediteran 27.0311.492 Andosol 27.4211.662 Total (km 2 ) 235.17100%

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

15. 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. 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

17. 17

18. 18 Schematic of input and outputs of the SWAT model

19. 19 Land use change scenario 2000 2005 Land use20002005Change (%) Urban Area20.6422.71 9.11 Forest92.6688.96 -4.16 Dry Field36.355.06 -86.08 Mixed – Dry Field30.0121.43 -28.59 Rice Field55.5197.01 42.78 Total (km 2 )235.17

20. 20 20052010 Land use20052010Change (%) Urban Area22.7128.9821.64 Forest88.9679.4-12.04 Dry Field5.0612.5659.71 Mixed – Dry Field21.4313.57-57.92 Rice Field97.01100.663.63 Total (km 2 )235.17

21. 21 Period 2000-2001 Discharge Calibration

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

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

24. 24 Average Organic N (kg/ha) Average Organic N (kg/ha)

25. 25 Average Organic P (kg/ha) Average Organic P (kg/ha) Monthly P Organic (kg P/ha) SUB Basin 3 0.000 0.020 0.040 0.060 0.080 0.100 0.120 0.140 0.160 JanFebMarAprlMeiJunJulagstSeptOktbNovDec Month Organic P (kg P/ha) 200020052010

26. 26 Stream organic n 2000organic n 2005organic N 2010

27. 27 Average Monthly Organic N Transported With Water Into ReachThe Sub Basin 4 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 JanFebMarAprlMeyJunJulAgstseptOktbrNovDec Month Organic N (g/lt) organic n 2000 organic n 2005 organic N 2010 Nitrogen

28. 28 Phosphorous

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

30. 30 Correlation between simulation and measurement R 2 =0,61

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

32. 32 Correlation between simulation and measurement (R 2 =0,78)

33. 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 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 SWAT model has been applied to evaluate and estimate the Selorejo reservoir The simulation result was found to be under estimated 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 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 Further study on other parameters is required to determine the causes of the drop of water quality in Selorejo Reservoir

34. 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. 35 YOU THANK