Global climate change and recent changes in Indonesia water resources

Transcription

1 The 4 th GEOSS Asia Pacific Symposium: Hydrometeorological and Related Disaster and Water Resources Management, March 10 12, 2010, Bali Global climate change and recent changes in Indonesia water resources Hidayat PAWITAN Bogor Agricultural University, Bogor 16680, Indonesian Hydrology Society (MHI) hpawitan@ipb.ac.id

2 Introduction Floods, Droughts, and Forest fires are common natural disasters that occurred frequently in many parts of Indonesia and have caused substantial physical, financial and human losses. It is also well known now that ENSO phenomena as one of the major factors related to these extreme events Many economic sectors are influenced severely by these recurrent disasters, including in agriculture, forestry and the environment Therefore, any possible initiatives and explanation of these cause-effect disasters would be of much value to minimize the negative impacts Strategy, programs and activities are on-going to overcome these, also in relation to Climate Change Adaptation and Mitigation Program

3 Past and on going study For the purpose of study, extensive monthly rainfall and river discharge data were collected, especially for Java Island simple hydrologic balance relating rainfall to river discharge were employed. Calculate dependable flows defined as 80% exceeding probability were calculated, and future water availability was projected considering climate change scenarios

4 Locations of hydrometric stations at major river basins on Java

5 Study results: 1. Dependable flows 2. Long term change of hydrological water balance on Java Island 3. Sign of Climate Change 4. Implication to water resources management

6 Figure 2. Daily discharge of Ciujung-Kragilan, Figure 3. Daily discharge of Cisadane Batu beulah, Water Cycle and Flow Trends of Java Major Rivers Figure 4. Daily discharge of Citarum Nanjung,

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8 Dependable flows for some major rivers in Java island No. River-Station name Basin area [km 2 ] Qmean [m 3 /s] Q80% [m 3 /s] Q90% [m 3 /s] 1 Ciujung-Kragilan Citarum-Nanjung Cimanuk-Monjot Citanduy-Petaruman K.Progo-Bantar B.Solo-Babat Brantas-Mojokerto

9 Trends of rainfall and river discharges in Java Sungai-stasiun Luas DAS [km 2 ] Tren Curah Hujan [mm/tahun] Tren Debit Sungai [m 3 /s/tahun] Ciujung-Kragilan ,120 Citarum-Tanjungpura ,772-0, 396 Cimanuk-Jatibarang ,087-0,290 B.Solo-Babat ,908-0,286 K.Brantas - Mojokerto ,214 0,060 K.Progo-Duwet ,517-0,168 K. Serayu-Rawalo ,459-0,110 Citanduy-Karangsari ,362-0,310

10 Projection of monthly discharge of Java rivers, No Sungai Stasiun Area (m 3 /s) (Km 2 ) [%] 2050 [%] 1 Ciujung Kragilan Citarum Tanjungpura , Cimanuk Jatibarang B.Solo Babat Brantas Mojokerto Progo Duwet Serayu Rawalo Citanduy Karangsari Catatan: proyeksi 2030 dan 2050 mengasumsikan tren linier.

11 Trend analysis and long term hydrologic balance for Citarum Upper Catchment Trend Curah Hujan, Limpasan, dan Sisa Limpasan Tahunan Tinggi/Jeluk (mm) y 1 = 0,0482x 2-10,53x ,7 y 2 = 0,0142x 2-3,1063x , y 3 = 0,034x 2-7,4236x , Curah Hujan Limpasan Sisa Limpasan Tahun

12 Trend analysis and long term hydrologic balance for Bengawan Solo Basin y = 1.616x mm P Q P Q y = 0.476x

13 Summary of trends of river flow patterns according to basin sections No. River Name Trends of Flow patterns Upstream Middle Downstream 1 Ciujung 2 Cisadane 3 Citanduy Very decreasing Moderately decreasing Moderately increasing decreasing Highly increasing Increasing 4 Citarum Normal - 5 Cimanuk 6 Serayu 7 Bengawan Solo Very decreasing Decreasing Highly increasing Moderately decreasing Moderately decreasing Moderately decreasing Decreasing - Decreasing Decerately decreasing Normal Decreasing Moderately decreasing

14 Indication of climate changes on Java major river basins No River basin Rainfall trend* River discharge trend* Before 1960 After 1960 Before 1960 After Citarum 2 Cimanuk 3 Bengawan Solo 4 Brantas 5 Progo 6 Serayu 7 Citanduy

15 LIKELY TRENDS It is believed that at present conditions, the specific discharges of Java s rivers are somewhat lower than those of historical conditions Significant changes had occurred dominated with decreasing trends in the downstream river sections Though decreasing regional rainfall in Java island is very much attributed to ENSO and Indian Ocean Dipole Mode, but the disappearing of Java forest cover in the past century also played significant role.

16 FACTORS AFFECTING REGIONAL WATER RESOURCES Anthropogenic influences due to population pressures with land hungry Land use changes and forest conversion Sedimentation, water pollution and eutrophication of water bodies Climate variability and likely changes Uncertainties generated to quality of available data

17 NEED OF ACTIONS: Proposed Activities Proper water resources management at regional level to fulfill the different water uses Monitoring of climate variability and water related disasters based on best available technologies to determine climate variability, regional surface water availability, and water related disasters Encourage collaborative researches and information exchanges among scientists in Asian Pacific region

18 Concluding Remarks Java rainfall indicates decreasing trend that implies lower river discharges that varies between +0,8 8,3% by 2030 and between +1,3 13,8% by 2050, which is equivalent to rainfall projection due to climate change scenarios. Indonesia certainly has serious problems in water resources management, partly due to serious uncertainties to fulfill the different water uses. Better monitoring and researches initiatives taking advantage geo environmental satellite and remote sensing technology are required. Future collaborative researches and information exchanges among scientists in Asian Pacific region certainly can contribute to better understanding of our nature and can enhance the environmental betterment that support better living conditions.

19 TERIMA KASIH