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-A FEASIBILITY STUDY ON CAGAYAN RIVER BASIN (TUGUEGARAO AND ENRILE) 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-A FEASIBILITY STUDY ON CAGAYAN RIVER BASIN (TUGUEGARAO AND ENRILE) 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) Tuguegarao Location Map and of Cagayan Enrile TUGUEGARAO CITY (Capital) µ ENRILE Cataggaman Enrile Alibago Legend Revetment Alignment Rivers River Basin 0 0.5 1 2 3 4 Kilometers Location Map of Cagayan 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-A: F/S ON CAGAYAN RIVER BASIN (TUGUEGARAO AND ENRILE) 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 1.2.1 Objectives of the Sector Loan Project on Disaster Risk Management............. 1-2 1.2.2 Objectives of the Preparatory Study................................................................. 1-2 1.3 Composition of the Final Report .............................................................................. 1-2 CHAPTER 2 NATURAL CONDITION OF THE STUDY AREA ............................... 2-1 2.1 Location ....................................................................................................................2-1 2.1.1 Topography and Geology ................................................................................. 2-1 2.1.2 Geology ............................................................................................................ 2-2 2.2 Meteo-Hydrology and River System of Cagayan River Basin................................. 2-4 2.2.1 Meteorology of the Cagayan River Basin ........................................................ 2-4 2.2.2 River System in Cagayan River Basin ............................................................. 2-5 2.2.3 General Features of Present River Channel...................................................... 2-6 2.2.4 River Morphology............................................................................................ 2-7 2.3 Flood......................................................................................................................... 2-9 - i - 2.3.1 River Overflow Flood....................................................................................... 2-9 2.3.2 Bank Erosion and Sedimentation ..................................................................... 2-9 CHAPTER 3 SOCIO-ECONOMIC CONDITIONS ..................................................... 3-1 3.1 Population and Economy.......................................................................................... 3-1 3.2 Land Use Profiles ..................................................................................................... 3-2 3.3 General Economic Profile......................................................................................... 3-4 3.4 Water Use.................................................................................................................. 3-5 3.5 Public Hazards.......................................................................................................... 3-6 3.5.1 Human-Induced Hazards.................................................................................. 3-6 3.5.2 Natural Hazards................................................................................................ 3-6 3.6 Past and On-going Public Works Projects ................................................................ 3-7 CHAPTER 4 ANALYSIS ON FUTURE POPULATION AND LAND USE............... 4-1 4.1 Future Land Use Condition ...................................................................................... 4-1 4.2 Population Projections (2010-2020) ......................................................................... 4-2 4.3 Trends of Urban Development and Population Increase .......................................... 4-3 CHAPTER 5 HYDROLOGIC AND HYDRAULIC ANALYSIS ................................. 5-1 5.1 General...................................................................................................................... 5-1 5.1.1 Summary of Previous Flood Runoff Estimation .............................................. 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................................................................................................... 5-5 5.4 Flood Inundation Analysis........................................................................................ 5-5 5.4.1 General ............................................................................................................. 5-5 5.4.2 Flood Inundation Model................................................................................... 5-6 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 and F/S ................................................ 6-1 6.1.2 Current Status in the Basin and Recommendation of 2002 F/S Study ............. 6-3 6.1.3 Core Areas to be Protected by Structural Measures in the Sector Loan Project .................................................................................. 6-11 6.1.4 Basic Concept for Flood Control.................................................................... 6-12 6.2 Planning Framework............................................................................................... 6-15 6.2.1 Target Project Completion Year...................................................................... 6-15 6.2.2 Social Framework........................................................................................... 6-15 6.2.3 Design Framework......................................................................................... 6-16 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 Applied Structural Measure.............................................................................. 7-4 7.1.6 Preliminary Design of River Facilities ............................................................. 7-7 7.1.7 Construction Plan............................................................................................. 7-9 7.1.8 Cost Estimation .............................................................................................. 7-15 7.2 Economic Evaluation of Project ............................................................................. 7-19 7.2.1 Methodology................................................................................................... 7-19 7.2.2 Basic Unit for Estimation of Economic Benefit............................................. 7-20 7.2.3 Identification of Economic Benefit ...............................................................