Assessing Impact of Land Use and Climate Changes on River Flow and Electricity Generation: Case Study at Citarum Watershed of Bandung District Rizaldi Boer, Delon Martinus, Ahmad Faqih and Perdinan Laboratory of Climatology, Department of Geophysics and Meteorology, Bogor Agricultural University E-mail: rizaldiboer@gmail.com
Study Site: Upper Citarum Jatiluhur Dam Cirata Dam Saguling Dam Upper Citarum Covering an area of about 72 thousand ha There are three dams ~ vital for meeting water demand of about 11 districts within watershed and 5 districts outside the watershed (north coast of West Java)
Monthly Average: Inflows to the three Dams in El- Nino, Normal and La-Nina years 643 m Inflow 625 m SAGULING 22 m 26 m 17 m Inflow (m3/s) Local Inflows CIRATA 87.5 m 2 16 12 8 4 El-Nino Normal La-Nina 1 2 3 4 5 6 7 8 9 1 1112 2 Month 16 Local Inflows JATILUHUR/ H. JUANDA Inflow (m3/s) Inflow (m3/s) 45 4 35 3 25 2 15 1 5 12 8 4 El-Nino Normal La-Nina 1 2 3 4 5 6 7 8 9 11112 El-Nino Normal La-Nina Month 1 2 3 4 5 6 7 8 9 1 11 12 Month Sea level
Outflows from the three dams in normal and dry years Inflow (m3/s) 14 12 1 8 6 4 2 Outflow from Saguling Dry years Normal years 1 2 3 4 5 6 7 8 9 1 11 12 2 Month Outflow from Cirata 643 m 625 m SAGULING 22 m outflow 26 m 17 m Inflow CIRATA 87.5 m outflow Inflow outflow Inflow (m3/s) JATILUHUR/ H. JUANDA Inflow (m3/s) 25 2 15 1 5 15 1 5 Dry years Normal years 1 2 3 4 5 6 7 8 9 1 11 12 Month Outflow from Jatiluhur Dry years Normal years 1 2 3 4 5 6 7 8 9 1 11 12 Month Sea level
Outflow and power generation 6 5 Saguling Cirata Jatiluhur Power (GWh) 4 3 2 In extreme drought years the minimum outflow from the dams were less than 5 m3/s) y = 2.2137x y =.6942x 1 y =.4578x 5 1 15 2 25 Outflow (m3/s)
Contribution of Saguling, Cirata and Jatiluhur HEP to Total Electricity Production of HEPs in Jamali Total Total HEPs HEPs capacity about about 252 252 MW MW HEP Saguling 28% HEP Area 1 1% HEP Area 2 2% HEP Area 4 2% HEP Area 3 HEP Sutami 5% 4% HEP Brantas Non-Sutami 5% HEP Jatiluhur 7% HEP Cirata 39% HEP Mrica 7% The three HEPs contributes to about 74% of the Total HEPs of Jamali. The decrease in electricity production from these three HEPs will have serious effect on economic activities. In drought years, HEPs capacity drops by about 6%. Many people believes that the decrease in forest cover has deteriorate the impact
Historical Land Use Changes Area (ha) Percent change Land Use 89 93 99 1 89-93 93-99 99-1 89-1 Bare land and shrub land 2694 515 1469 1186 89.5 15.1 13.3 34.3 Agriculture area 1/ 126536 124755 12651 126335-1.4 1.4 -.1 -.2 Forest & vegetation covers 2/ 4615 44182 34928 31951-4.2-2.9-8.5-3.7 Settlements 2639 3429 4547 5522 29.9 32.6 21.4 19.2 Urban and Industries 93 9597 1627 11426 6.3 1.7 7.5 26.5 Dam/Lakes 312 247 243 223-2.9-1.5-8.5-28.7 TOTAL 187316 187316 187316 187316
Change of Forest Cover in the Upper Citarum Forest Area (ha) 5 4 3 2 1 1989 1993 1999 21 Year Forest Area Percent of total Area 3 25 2 15 1 5 Percent of Total Area
Critical Land in Citarum 18 15 12 9 6 3 Critical Land (ha) Bandung* Cianjur Karawang Purwakarta Bandung City Kota Cimahi Source: BP-DAS Citarum-Ciliwung (23)
Community Perception About 85% of respondents stated that there is an increase in drought and flood frequency and intensity (Sulandari et al., 24) Dialog between stakeholders and scientist at Bandung, it was suggested that at least 4% of watershed area should be maintained as conservation zone (forest cover) ~ It is believed that increasing forest cover will diminish the damage of flood and drought risk Forest Area (ha) 5 4 3 2 1 Forest Area Percent of total Area 1989 1993 1999 21 Year In 21, government targeted to increase forest cover up to 48% of the total areas 3 25 2 15 1 5 Percent of Total Area
Objectives To evaluate impact of land use and climate changes scenarios on river flow at Nanjung (Upper watershed) and on electricity generation Citarum Upper Catchments
Step of Analysis Observed Stream flow Historical Climate data VIC-BASIN Model Good? Select the base flow Historical Land Use Change base flow and run off parameters Develop relationship between % forest cover and base flow Land Use Scenarios Estimate base flow parameter VIC-BASIN Model Climate Scenarios GCM Downscaled GCM to Study sites CLIMGEN Evaluate the impact and develop recommendation
Critical Land and Rehabilitation Plan for the Four Land Use Scenario for Upper Citarum Watershed Area (ha) 16 14 12 1 8 6 4 2 23 Mitigation 1 Mitigation 2 Mitigation 3 Government Critical land Rehabilitation
Land Use Scenarios Land use category Area (ha) LU-21 MIT-1 MIT-2 MIT-3 RUTR Shrubs 11862 9578 5 Agriculture 126494 118465 124167 115736 77426 Forest/Agroforest 31825 35921 4599 54445 89426 City/Industrial areas 16912 22849 16931 16912 216 Dam/Lakes 223 53 223 223 448 TOTAL 187316 187316 187316 187316 187316 Percent forest cover (%) 17 19 25 29 48 1989
Land Use Scenarios 17%: Baseline 19%: MIT-1 25%: MIT-2 29%: MIT-3 48%: RTRW Shrubs Dam/Lake Forest/Agroforest Agriculture City/Industrial Area
Relationship between base flow parameter and forest cover Baseflow Parameter.6.5.4.3.2.1 y =.521Ln(x) - 1.247 R 2 =.9553 Citarum Sumber Jaya 1 15 2 25 3 Percent Forest Cover (%)
Comparison between observed and Downscaled 6 5 4 3 2 1 1961 1962 1963 1964 1965 1966 1967 1968 1969 197 1971 1972 1973 1974 1975 1976 1977 1978 1979 198 1981 1982 1983 1984 1985 Observed Data Downscaled Data TIME (Month) RAINFALL (mm)
Comparison between Observed (Above) and Downscaled Rainfall (Below) -5.8 DJF baseline rainfall from downscaling (1961-199) MAM baseline rainfall from observation (1961-199) JJA baseline rainfall from observation (1961-199) SON baseline rainfall from downscaling (1961-199) -5.8-5.8-5.8 DJF MAM JJA SON -6-6.2-6.4-6.6-6.8-7 -7.2 15 14 13 12 11 1 9 8 7 6 5 4 3 2 1-6 -6.2-6.4-6.6-6.8-7 -7.2-6 15 14 13-6.2 12 11 1-6.4 9 8-6.6 7 6 5-6.8 4 3 2-7 1-7.2 15 14 13 12 11 1 9 8 7 6 5 4 3 2 1-6 -6.2-6.4-6.6-6.8-7 -7.2 15 14 13 12 11 1 9 8 7 6 5 4 3 2 1-7.4 16.6 16.8 17 17.2 17.4 17.6 17.8 18 18.2-7.4 16.6 16.8 17 17.2 17.4 17.6 17.8 18 18.2-7.4 16.6 16.8 17 17.2 17.4 17.6 17.8 18 18.2-7.4 16.6 16.8 17 17.2 17.4 17.6 17.8 18 18.2 DJF baseline rainfall from observation (1961-199) MAM baseline rainfall from downscaling (1961-199) JJA baseline rainfall from downscaling (1961-199) SON baseline rainfall from observation (1961-199) -5.8-6 -6.2-6.4-6.6-6.8-7 -7.2-5.8-6 -6-6 15 15 15 14 14 14 13-6.2 13-6.2 13-6.2 12 12 12 11 11 11 1-6.4 1-6.4 1-6.4 9 9 9 8 8 8-6.6-6.6 7 7 7-6.6 6 6 6 5 5 5-6.8-6.8-6.8 4 4 4 3 3 3 2-7 2-7 2-7 1 1 1-7.2-7.2-7.2-5.8 DJF MAM JJA SON -5.8 15 14 13 12 11 1 9 8 7 6 5 4 3 2 1-7.4-7.4-7.4-7.4 16.6 16.8 17 17.2 17.4 17.6 17.8 18 18.2 16.6 16.8 17 17.2 17.4 17.6 17.8 18 18.2 16.6 16.8 17 17.2 17.4 17.6 17.8 18 18.2 16.6 16.8 17 17.2 17.4 17.6 17.8 18 18.2
Projected Annual Rainfall at Citarum Watershed 27 High Scenario Annual rainfall 26 25 24 23 22 Low Scenario 21 2 Baseline A2 22 A2 25 A2 28 B2 22 B2 25 GCM outputs from ECHAM model downloaded from Data Distribution Centre B2 28 Rainfall (mm) 4 35 3 25 2 15 1 Baseline Low-Scenario High-Scenario 5 1 2 3 4 5 6 7 8 9 1 11 12 Month
Result of Validation Using CLIMGEN Streamflow (m3/s) 14 12 1 8 6 4 2 Mean SS_UGDC Observed Streamflow Streamflow (m3/s) 35 3 25 2 15 1 5 Mean SS_UGCD Observed Streamflow 1 2 3 4 5 6 7 8 9 11112 1 37 73 19 145 181 217 253 289 325 361 Month Julian Day
Distribution of stream flow under different land use and climate scenarios Under baseline and low climate scenarios, increasing forest cover more than 2% and up to 47% of the total land areas would not change the distribution of stream flow Under high climate scenario, the distribution of stream flow under baseline and mitigation 1 land use scenario (percent land use cover is between 17% and 19%) was different from those under Mitigation 2 and 3 scenarios (percent forest cover is between 25% and 29%) and under RTRW (percent forest cover is 48%). Cumulative Probability (%) 1.2 1.8.6.4.2 Baseline climate 2 4 6 Discharge (m3/s) 21 Mit-1 Mit-2 Mit-3 RUTR Cumulative Probability (%) 1.2 1.8.6.4.2 Low Scenario 2 4 6 Discharge (m3/s) 21 Mit-1 Mit-2 Mit-3 RUTR Cumulative Probability (%) 1.2 1.8.6.4.2 High Scenario 2 4 6 Discharge (m3/s) 21 Mit-1 Mit-2 Mit-3 RUTR
Relationship between Inflow, Outflow and Electricity Generation O utflow (m 3/s) 16 14 12 1 8 6 4 2 y =.5693x + 42.757 R 2 =.99 y =.831x - 14.992 R 2 =.94 2 4 6 8 1 12 14 16 18 Inflow (m3/s) Power (GWh) 35 3 25 2 15 1 5 y = 2.2137x R 2 =.993 2 4 6 8 1 12 14 Outflow (m3/s) The result of analysis suggested that If the forest cover were not increased to more than 25%, the frequency of producing electricity power of less than 1 GWh during dry season will increase under the three climate scenarios. The operation of this HEP in the dry season in critical to meet electricity demand during peak load