Assessing Impact of Land Use and Climate Changes on River Flow and Electricity Generation: Case Study at Citarum Watershed of Bandung District

Transcription

1 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

2 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)

3 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 El-Nino Normal La-Nina Month 16 Local Inflows JATILUHUR/ H. JUANDA Inflow (m3/s) Inflow (m3/s) El-Nino Normal La-Nina El-Nino Normal La-Nina Month Month Sea level

4 Outflows from the three dams in normal and dry years Inflow (m3/s) Outflow from Saguling Dry years Normal years 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) Dry years Normal years Month Outflow from Jatiluhur Dry years Normal years Month Sea level

5 Outflow and power generation 6 5 Saguling Cirata Jatiluhur Power (GWh) In extreme drought years the minimum outflow from the dams were less than 5 m3/s) y = x y =.6942x 1 y =.4578x Outflow (m3/s)

6 Contribution of Saguling, Cirata and Jatiluhur HEP to Total Electricity Production of HEPs in Jamali Total Total HEPs HEPs capacity about about 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

7 Historical Land Use Changes Area (ha) Percent change Land Use Bare land and shrub land Agriculture area 1/ Forest & vegetation covers 2/ Settlements Urban and Industries Dam/Lakes TOTAL

8 Change of Forest Cover in the Upper Citarum Forest Area (ha) Year Forest Area Percent of total Area Percent of Total Area

9 Critical Land in Citarum Critical Land (ha) Bandung* Cianjur Karawang Purwakarta Bandung City Kota Cimahi Source: BP-DAS Citarum-Ciliwung (23)

10 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) Forest Area Percent of total Area Year In 21, government targeted to increase forest cover up to 48% of the total areas Percent of Total Area

11 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

12 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

13 Critical Land and Rehabilitation Plan for the Four Land Use Scenario for Upper Citarum Watershed Area (ha) Mitigation 1 Mitigation 2 Mitigation 3 Government Critical land Rehabilitation

14 Land Use Scenarios Land use category Area (ha) LU-21 MIT-1 MIT-2 MIT-3 RUTR Shrubs Agriculture Forest/Agroforest City/Industrial areas Dam/Lakes TOTAL Percent forest cover (%)

15 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

16 Relationship between base flow parameter and forest cover Baseflow Parameter y =.521Ln(x) R 2 =.9553 Citarum Sumber Jaya Percent Forest Cover (%)

17 Comparison between observed and Downscaled Observed Data Downscaled Data TIME (Month) RAINFALL (mm)

18 Comparison between Observed (Above) and Downscaled Rainfall (Below) -5.8 DJF baseline rainfall from downscaling ( ) MAM baseline rainfall from observation ( ) JJA baseline rainfall from observation ( ) SON baseline rainfall from downscaling ( ) DJF MAM JJA SON DJF baseline rainfall from observation ( ) MAM baseline rainfall from downscaling ( ) JJA baseline rainfall from downscaling ( ) SON baseline rainfall from observation ( ) DJF MAM JJA SON

19 Projected Annual Rainfall at Citarum Watershed 27 High Scenario Annual rainfall 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) Baseline Low-Scenario High-Scenario Month

20 Result of Validation Using CLIMGEN Streamflow (m3/s) Mean SS_UGDC Observed Streamflow Streamflow (m3/s) Mean SS_UGCD Observed Streamflow Month Julian Day

21 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 (%) Baseline climate Discharge (m3/s) 21 Mit-1 Mit-2 Mit-3 RUTR Cumulative Probability (%) Low Scenario Discharge (m3/s) 21 Mit-1 Mit-2 Mit-3 RUTR Cumulative Probability (%) High Scenario Discharge (m3/s) 21 Mit-1 Mit-2 Mit-3 RUTR

22 Relationship between Inflow, Outflow and Electricity Generation O utflow (m 3/s) y =.5693x R 2 =.99 y =.831x R 2 = Inflow (m3/s) Power (GWh) y = x R 2 = 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

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