Baseline Assessment: Bago River Watershed and its Natural Parks Philippines Biodiversity and Watersheds Improved for Stronger Economy and Ecosystem Resilience (B+WISER) This publication was produced for review by the United States Agency for International Development. It was prepared by Chemonics International Inc. The Biodiversity and 26Watersheds June 201 5Improved for Stronger Economy and Ecosystem Resilience Program is funded by the USAID, Contract No. AID-492-C-13-00002 and implemented by Chemonics International in association with: Fauna and Flora International (FFI) Haribon Foundation World Agroforestry Center (ICRAF) The author’s views expressed in this publication do not necessarily reflect the views of the United States Agency for International Development or the United States Government. This publication was produced for review by the United States Agency for International Development. It was prepared by Chemonics International Inc. The Biodiversity and Watersheds Improved for Stronger Economy and Ecosystem Resilience Program is funded by the USAID, Contract No. AID-492-C-13-00002 and implemented by Chemonics International in association with: Fauna and Flora International (FFI) Haribon Foundation World Agroforestry Center (ICRAF) The author’s views expressed in this publication do not necessarily reflect the views of the United States Agency for International Development or the United States Government. Vulnerability Assessment of Bago River Watershed and its Natural Parks Philippines Biodiversity and Watersheds Improved for Stronger Economy and Ecosystem Resilience (B+WISER) Program Implemented with: Department of Environment and Natural Resources Other National Government Agencies Local Government Units and Agencies Supported by: United States Agency for International Development Contract No.: AID-492-C-13-00002 Managed by: Chemonics International Inc. in partnership with Fauna & Flora International (FFI) Haribon Foundation World Agroforestry Center (ICRAF) 26 June 2015 CONTENTS List of Figures................................................................................................................. iii List of Tables .................................................................................................................. iv List of Plates .................................................................................................................. iv Acronyms ........................................................................................................................ v Rationale ....................................................................................................................... vii The Bago Watershed and its Natural Parks ........................................................................... 1 The Climate Profile .......................................................................................................... 4 Baseline climate ..................................................................................................... 4 Climate scenario for Northern Negros in 2020 and 2050 ........................................ 6 Assessment Framework and Methodology ............................................................................ 8 Data Collection....................................................................................................... 8 Vulnerability Assessment ....................................................................................... 8 Hazards Assessment ............................................................................................. 9 Flood Hazard Assessment .................................................................................... 9 Drought Hazard Assessment .............................................................................. 11 Landslide Hazard Assessment ............................................................................ 13 Land Capability Classification .............................................................................. 14 Generation of Soil Erosion Potential ................................................................... 15 Rainfall Factor (R) ............................................................................................... 15 Soil Erodibility Factor (K) ..................................................................................... 16 Slope Length and Slope Gradient Factor (LS) .................................................... 17 Creation of Soil Loss Tolerance .......................................................................... 17 Determination of Soil Erosion Index .................................................................... 18 Generation of Land Capability Classification ....................................................... 18 Validation ............................................................................................................. 19 Findings .......................................................................................................................... 21 Hazards Assessment ........................................................................................... 21 Flood Hazard Assessment .................................................................................. 21 Drought Hazard Assessment .............................................................................. 32 Rain-Induced Landslide Hazard Assessment ..................................................... 44 Land Capability Classification .............................................................................. 56 Protection Areas .................................................................................................. 56 Key Biodiversity Areas ......................................................................................... 56 Stream Buffer Areas ............................................................................................ 58 VULNERABILITY ASSESSMENT OF THE BAGO WATERSHED AND ITS NATURAL PARKS | i Production Areas ................................................................................................. 59 Multiple Use Zone ................................................................................................ 59 Limited Production Zone ...................................................................................... 59 Unlimited Production Zone .................................................................................. 59 Conclusion .................................................................................................................... 63 Recommendation .......................................................................................................... 64 References .................................................................................................................... 65 ii | VULNERABILITY ASSESSMENT OF THE BAGO WATERSHED AND ITS NATURAL PARKS LIST OF FIGURES Figure 1. The Bago Watershed and its surrounding natural parks ............................................ 2 Figure 2. Tracks of tropical cyclones that crossed the province of Negros Occidental (1948 – 2009) ............................................................................................................. 5 Figure 3. Observed and projected monthly rainfall in Northern Negros .................................... 6 Figure 4. Framework of the vulnerability assessment ............................................................... 9 Figure 5. Framework for erosion-based land capability classification system ......................... 15 Figure 6. Site visited during the validation in the Bago Watershed and its natural parks ........ 19 Figure 7. Flood vulnerability based on observed scenario under the CNCM3 model in the Bago Watershed, Northern Negros .......................................................................... 27 Figure 8. Flood vulnerability (2020s period) based on CNCM3 model (A1B scenario) in the Bago Watershed, Northern Negros .................................................................... 28 Figure 9. Flood vulnerability (2050s period) based on CNCM3 model (A1B scenario) in the Bago Watershed, Northern Negros .................................................................... 29 Figure 10. Flood Vulnerability (2020s period) based on CNCM3 model (A1B scenario) in the Bago Watershed, Northern Negros .................................................................... 30 Figure 11. Flood Vulnerability (2050s period) based on CNCM3 model (A1B scenario) in the Bago Watershed, Northern Negros .................................................................... 31 Figure 12. Standardized precipitation index based on CNCM3 A1B scenario of the Negros Occidental Province .................................................................................................. 34 Figure 13. Standardized precipitation index based on CNCM3 A2 scenario of the Negros Occidental Province .................................................................................................. 34 Figure 14. Drought Vulnerability based on observed scenario under the CNCM3 model (A1B scenario) in the Bago Watershed and its natural parks ................................... 39 Figure 15. Drought Vulnerability (2020s period) based on CNCM3 model (A1B scenario) in the Bago Watershed and its natural parks ............................................................... 40 Figure 16. Drought Vulnerability (2050s period) based on CNCM3 model (A1B scenario) in the