DEPARTMENT OF PUBLIC WORKS AND HIGHWAYS THE REPUBLIC OF THE PHILIPPINES THE PREPARATORY STUDY FOR SECTOR LOAN ON DISASTER RISK MANAGEMENT IN THE REPUBLIC OF THE PHILIPPINES FINAL REPORT PART II-B FEASIBILITY STUDY ON ILOG-HILABANGAN RIVER BASIN (KABANKALAN AND ILOG) JANUARY 2010 JAPAN INTERNATIONAL COOPERATION AGENCY CTI ENGINEERING INTERNATIONAL CO., LTD. in association with NIPPON KOEI CO., LTD GED JR 10-012 DEPARTMENT OF PUBLIC WORKS AND HIGHWAYS THE REPUBLIC OF THE PHILIPPINES THE PREPARATORY STUDY FOR SECTOR LOAN ON DISASTER RISK MANAGEMENT IN THE REPUBLIC OF THE PHILIPPINES FINAL REPORT PART II-B FEASIBILITY STUDY ON ILOG-HILABANGAN RIVER BASIN (KABANKALAN AND ILOG) JANUARY 2010 JAPAN INTERNATIONAL COOPERATION AGENCY CTI ENGINEERING INTERNATIONAL CO., LTD. in association with NIPPON KOEI CO., LTD Exchange Rate used in the Report is: US$ 1.00 = PhP. 49.70 = JpY. 93.67 Jp¥ 1.00 = PhP. 0.5306 (as of 31st August 2009) LIST OF REPORTS Summary Part I : Main Report Part II-A : Feasibility Study on the Lower Cagayan River Flood Control Project for the Sector Loan Application Part II-B : Feasibility Study on the Ilog Hilabangan River Flood Control Project for the Sector Loan Application Part II-C : Feasibility Study on the Tagoloan River Flood Control Project for the Sector Loan Application Needs Assessment Study on Flood Disasters Caused by Typhoons No.16 (ONDOY) and No.17 (PEPENG) THE PREPARATORY STUDY FOR SECTOR LOAN ON DISASTER RISK MANAGEMENT IN THE REPUBLIC OF THE PHILIPPINES FINAL REPORT PART II-B: F/S ON ILOG-HILABANGAN RIVER BASIN (KABANKALAN AND ILOG) LOCATION MAP COMPOSITION OF THE REPORT TABLE OF CONTENTS ABBREVIATION (REFER TO MAIN REPORT (PART-I)) TABLE OF CONTENTS Page CHAPTER 1 INTRODUCTION........................................................................... 1-1 1.1 Background of the Study ............................................................................... 1-1 1.2 Objectives of the Study.................................................................................. 1-2 1.3 Composition of the Final Report ................................................................... 1-3 1.2.1 Objectives of the Sector Loan Project on Disaster Risk Management .. 1-2 1.2.2 Objectives of the Preparatory Study ...................................................... 1-2 CHAPTER 2 NATURAL CONDITION OF THE STUDY AREA..................... 2-1 2.1 Location......................................................................................................... 2-1 2.1.1 Topography ............................................................................................ 2-1 2.1.2 Geology.................................................................................................. 2-3 2.2 Meteo-Hydrology and River System of Ilog-Hilabangan River Basin ......... 2-4 2.2.1 Meteorology of Ilog-Hilabangan River Basin ....................................... 2-4 2.2.2 River System in Ilog-Hilabangan River Basin....................................... 2-5 2.3 Flood.............................................................................................................. 2-7 2.4 Related Information....................................................................................... 2-8 - i - 2.4.1 Negros Island Integrated Water Resources Management Council......... 2-8 2.4.2 Flood Mitigation Projects in the Past..................................................... 2-9 CHAPTER 3 CHAPTER 3 SOCIO-ECONOMY................................................ 3-1 3.1 Population and Economy............................................................................... 3-1 3.2 Land Use........................................................................................................ 3-2 3.3 The General Economic Profiles..................................................................... 3-3 3.4 Water Utilization............................................................................................3-4 3.5 Public Hazards............................................................................................... 3-5 3.5.1 River Overbank Flows ........................................................................... 3-5 3.5.2 Water Pollution...................................................................................... 3-5 3.5.3 Solid Waste ............................................................................................ 3-5 CHAPTER 4 ANALYSIS OF FUTURE LAND USE AND POPULATION ..... 4-1 4.1 Future Land Use Conditions.......................................................................... 4-1 4.2 Population Projection.................................................................................... 4-1 4.3 Trends of Urban Development and Population Increase............................... 4-2 CHAPTER 5 HYDROLOGIC AND HYDRAULIC ANALYSIS....................... 5-1 5.1 General .......................................................................................................... 5-1 5.1.1 Summary of Flood Runoff Estimation in Previous Study ..................... 5-1 5.1.2 Approach for this Study......................................................................... 5-2 5.2 Hydrology...................................................................................................... 5-3 5.3 Hydraulic Analysis ........................................................................................ 5-4 5.3.1 Target Area............................................................................................. 5-4 5.3.2 River Cross-section Survey.................................................................... 5-4 5.3.3 Initial Boundary Condition .................................................................... 5-4 5.3.4 Flow Capacity........................................................................................ 5-4 5.4 Flood Inundation Analysis............................................................................. 5-4 5.4.1 General................................................................................................... 5-4 5.4.2 Flood Inundation Model ........................................................................ 5-5 CHAPTER 6 PLANNING FRAMEWORK......................................................... 6-1 6.1 Basic Concepts on Planning Framework....................................................... 6-1 - ii - 6.1.1 Summary and Outline of Current M/P................................................... 6-1 6.1.2 Core Areas to be Protected by Structural Measures in the Sector Loan Project .................................................................................................... 6-4 6.1.3 Basic Concept for Flood Control ........................................................... 6-5 6.2 Planning Framework ..................................................................................... 6-8 6.2.1 Target Project Completion Year............................................................. 6-8 6.2.2 Social Framework.................................................................................. 6-8 6.2.3 Design Framework................................................................................. 6-9 CHAPTER 7 STRUCTURAL FLOOD MITIGATION PLAN.......................... 7-1 7.1 Structural Flood Mitigation Plan against River-Overflow Flood.................. 7-1 7.1.1 Maximum Design Scale Examined in the Study ................................... 7-1 7.1.2 Potential Measures................................................................................. 7-1 7.1.3 Alternative Flood Mitigation Plans against River-overflow.................. 7-3 7.1.4 Flood Simulation Analysis..................................................................... 7-3 7.1.5 Optimum Structural Mitigation Plan (Summary of Simulation Analysis)........................................................ 7-4 7.1.6 Preliminary Design of River Facilities .................................................. 7-7 7.1.7 Construction Plan................................................................................... 7-8 7.1.8 Cost Estimation.................................................................................... 7-14 7.2 Economic Evaluation of Project.................................................................. 7-18 7.2.1 Methodology........................................................................................ 7-18 7.2.2 Basic Unit for Estimation of Economic Benefit .................................. 7-19 7.2.3 Identification of Economic Benefit...................................................... 7-23 7.2.4 Estimation of Economic Cost .............................................................. 7-24 7.2.5 Results of Economic Evaluation for the Project and Conclusion........ 7-26 CHAPTER 8 NON-STRUCTURAL FLOOD MITIGATION PLAN................ 8-1 8.1 Overview of Eligible Measures..................................................................... 8-1 8.2 Practice of Non-structural Measures in The Philippines............................... 8-1 8.2.1 Preparedness Plan.................................................................................. 8-1 8.2.2 Flood Early Warning System ................................................................. 8-7 - iii - 8.3 Present Activities related to Non-structural Measures in the Ilog-Hilabangan River Basin................................................................. 8-14 8.3.1 Disaster Coordinating Council............................................................. 8-14 8.4 Non-Structural Measures