No.
The Department of Water Induced Disaster Prevention, Ministry of Water Resources The Department of Roads, Ministry of Physical Planning and Works The Republic of Nepal
THE STUDY ON DISASTER RISK MANAGEMENT FOR NARAYANGHARH – MUGLING HIGHWAY
FINAL REPORT
Volume II Main Report
February 2009
JAPAN INTERNATIONAL COOPERATION AGENCY
NIPPON KOEI CO., LTD.
GED JR
09-014
The Department of Water Induced Disaster Prevention, Ministry of Water Resources The Department of Roads, Ministry of Physical Planning and Works The Republic of Nepal
THE STUDY ON DISASTER RISK MANAGEMENT FOR NARAYANGHARH – MUGLING HIGHWAY
FINAL REPORT
Volume II Main Report
February 2009
JAPAN INTERNATIONAL COOPERATION AGENCY
NIPPON KOEI CO., LTD.
COMPOSITION OF REPORTS
Volume Report Name Language
Volume I Summary English
Volume II Main Report English
Volume III Data and Drawing English
Volume IV Technical Guide English
The Study on Disaster Risk Management for Narayangharh-Mugling Highway Main Report
Nepal Kathmandu
Marsyangdi hydro power plant
Mugling
CH 30km
CH 20km
Narayangharh - Mugling Highway
CH 10km
Study Area
CH 0km Narayangharh
0 5 km
Location Map of the Study Area
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Definition of Terms for Risk Assessment
Terms Definitions Disturbance : Deformation of the slope and/or road structures or slope collapse which has not reached the road.
Road Closure : A disaster which causes closure of the whole or partial width of Disaster the road [RCD] Deformations and collapses that do not close the road are not necessarily regarded as a RCD but just as a 'Disturbance'.
Loss : Monetary amount of damage caused by a disaster, specifically defined as the sum of the reopening cost, human lives lost, vehicle lost and losses of traffic suspension.
Risk : The total damage characterized by the potential frequency and magnitude of the disaster. Annual total loss is an expression of the risk. The risk is distinguished from the hazard, which could be defined, in the case of this Study, as the overt danger to the road and road users.
Frequency of Road : The number of RCD occurrences per year for a slope (Nos. of Closure Disasters per RCD/year) Year [FRCD] FRCDp : Potential FRCD FRCDa : Actual FRCD
Intensity of Road : Average RCD occurrences per km year for a road section, i.e. Closure Disasters of a the total FRCD’s for the road section divided by its length Road Section [IRCD] (Nos. of RCD/year/km) IRCDp : Potential IRCD IRCDa : Actual IRCD
Annual Loss due to : Annual loss induced by RCD of a slope or a stream (Rs/year) RCD [AL] ALp : Potential AL ALa : Actual AL
Intensity of Annual : Intensity of annual loss of per unit length per year Loss of a Road (Rs/year/km) Section [IAL] IALp : Potential IAL IALa : Actual IAL
Chainage : A point in the road represented by kilometer posts + displacement from the kilometer post in meters from starting point of a road section, as CH xx km + xxx m.
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The Study on Disaster Risk Management for Narayangharh-Mugling Highway Main Report Acronyms/Abbreviations
AADT Average Annual Daily Traffic ACLoV Average Cancellation Loss of Vehicles ADB Asian Development Bank ADLoV Average Detour Loss of Vehicles ADPC Asian Disaster Preparedness Center ADRC Asian Disaster Reduction Center ALE Average Life Expectancy at birth ALp Potential Annual Loss of a site ANHD Average Numbers of Human Deaths per RCD ANVL Average Numbers of Vehicles Loss per RCD AR Automatic Rain gauge ARMP Annual Road Maintenance Plan ARR Assistant Resident Representative ASLoV Average traffic Suspension Loss of Vehicles ATP Average Traffic Persons of a vehicle AVS Average Vehicle Speed AWLoV Average Waiting Loss of Vehicles BCR Benefit Cost Ratio C Cost CARE Cooperative for American Relief Everywhere (NGO) CBS Central Bureau of Statistics CDMA Code division multiple access CDO Chief District Officer CEM Coefficient of Effectiveness of Structural Measure Effectiveness for FRCDp CH Chainage CP Cancellation Percentage C/P Counterpart(s) or Counterpart Organization(s) CPoWTP150 Cancellation percentage of Willingness to Pay equal to over than Rs 150 CPoWTP300 Cancellation percentage of Willingness to Pay equal to over than Rs 300 CPoWTP<150 Cancellation Percentage of Willingness to Pay under than Rs 150 instead of waiting DAL Decrease in Annual loss due to structural measure DALy Decrease in Annual Loss due to structural measure of y year DDC District Development Committee DDO District Development Office DG Director General DDG Deputy Director General DEM Digital Elevation Model
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DF Debris Flow DFID Department for International Development DF/R Draft Final Report DHM Department of Hydrology and Meteorology, Ministry of Environment, Science and Technology DP Detour Percentage DPdNH Detour Percentage divert to Naubise or Hetauda DPdPB Detour Percentage divert to Pokhara or Butawal DPO District Police Office DMG Department of Mines and Geology, Ministry of Industry Commerce and Supplies DMSPP Disaster Mitigation Support Program Project DoLIDAR Department of Local Infrastructure Development and Agriculture Road, Ministry of Local Development DOR Department of Roads, Ministry of Physical Planning and Works DOS Department of Survey, Ministry of Land Reform and Management DPTC Disaster Prevention Training Center DR Discount Rate DRO District Road Office DTM Department of Transport Management, Ministry of Labor and Transport Management DWIDP Department of Water Induced Disaster Prevention, Ministry of Water Resources EIA Environmental Impact Assessment EIRR Economic Internal Rate of Return ENPV Economic Net Present Value E/R Evaluation Report EU European Union FCR Fixed Cost for Reopening of a RCD F/R Final Report FRCD Frequency of Road Closure Disaster of a site FRCDa Actual Frequency of Road Closure Disaster of a site FRCDabm Actual Frequency of RCD of a site before structural measure is installed FRCDp Potential Frequency of Road Closure Disaster of a site FRCDpom Potential Frequency of Road Closure Disaster of a site without structural measure FRCDpwm Potential Frequency of Road Closure Disaster with structural measure FS Frequency Score for FRCDp F/S Feasibility Study FTP File Thrasher Protocol GDP Gross Domestic Product
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GIS Geographic Information System GON Government of Nepal GPS Global Positioning System GTZ Technical Cooperation of the Federal Republic of Germany GWHa Actual Gross Working Hours HLLp Potential Value of Human Lives Loss of a RCD IALp Potential Intensity of Annual Loss of a section INGO International Non-Governmental Organization IC/R Inception Report ICIMOD Integrated Centre for Integrated Mountain Development IEE Initial Environmental Evaluation IRCD Intensity of Road Closure Disaster IRCDp Potential Intensity of Road Closure Disaster of a section IRCS International Red Cross Society IT/R Interim Report JICA Japan International Cooperation Agency LF Lobar Force Lp Potential Loss of a RCD LRCpoF Potential Length of Road Closure section of Full width of a RCD LRCpoP Potential Length of Road Closure section of Partial width of a RCD LS Length of Section LTSp Potential Losses of Traffic Suspension of a RCD LWS Lutheran World Services MBT Main Boundary Thrust MCT Main Central Thrust MFT Main Frontal Thrust M/M Minutes of Meeting M-N Mugling-Narayangharh MNWIDPP Mugling-Narayangharh Water Induced Disaster Prevention Project MOEST Ministry of Environment Science and Technology MOFSC Ministry of Forests and Soil Conservation MOHA Ministry of Home Affairs MOIC Ministry of Information and Communication MOLD Ministry of Local Development MOLT Ministry of Labour and Transport Management MOPPW Ministry of Physical Planning and Works MOWR Ministry of Water Recourses M/P Master Plan MSL Mean Sea Level NAR Non Automatic Rain Gauge
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NCDp Numbers of Predicted Closure Days of the whole width of the road on the survey site per RCD NCDpV Numbers of predicted Closure Days of a Vehicle NCHpV Numbers of predicted Closure Hours of a Vehicle NDRA The Natural Disaster Relief Act NEA Nepal Electric Authority NGIIP National Geographic Information Infrastructure Program NGO Non Government Organization NK Nippon Koei Co., Ltd. N-M Narayangharh-Mugling Nos. Numbers NORAD Norwegian Agency for Development Cooperation NPC National Planning Commission NPO Nonprofit Organization NWP Non-Waiting Percentage O-D Origin – Destination PDM Project Design Matrix PIP Priority Investment Plan PM Project Manager PMED Planning Monitoring and Evaluation Division POP Population PP Pilot Project(s) PPD Policy and Planning Division PR/R Progress Report PVC Poly-Vinyl Chloride Q/N Questionnaire RCD Road Closure Disaster RCDp Potential Road Closure Disaster RCp Potential Reopening Cost of a RCD RF Rock Fall RRN Rural Reconstruction Nepal, NGO RRR Risk Reduction Ratio Rs (Nepalese) Rupee RSL Road Section Length S/C Steering Committee SCF Save the Children Found SDC Swiss Development Corporation SF Slope Failure SL Slide or Landslide SPM Suspended Particulate Matter
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SRN Strategic Road Network S/W Scope of Work TA Technical Assistance TCR Travel Conversion Ratio The Study The Study on the Disaster Risk Management for Narayangharh – Mugling Highway The Team The JICA Study Team TOR Terms of Reference TSDC Transport Sector Development Project UCLp Unit Potential Losses due to Cancellation of trip per vehicle per RCD UDL Unit Detour Loss UDLdNH Unit Detour Loss of a Vehicle when divert to Naubise or Hetauda UDLdPB Unit Detour Loss of a Vehicle when divert to Pokhara or Butawal UHL Unit Value of Human Lives Loss ULTS Unit Loss of Traffic Suspension of a vehicle UMN United Mission to Nepal UNDP United Nations Development Program URCpMoF Unit Reopening Cost per one mater length of Full width road closure URCpMoP Unit Reopening Cost per one mater length of Partial width road closure U.S. United State of America USAIDM-N United States Agency for International Development Mission to Nepal UVOC Unit Vehicle Operation Cost per km per vehicle UVL Unit Value of Vehicle Loss UVTT Unit Value of Traffic Time of a vehicle UWL Unit Waiting Loss of a vehicle VDC Village Development Committee VLp Potential value of Vehicle Loss of a RCD VOC Vehicle Operation Cost WB World Bank WFP World Food Programme W/G Working Group (comprising of the C/P) WH Waiting Hours WP Waiting Percentage W/S Workshop WTP Willingness To Pay y Year from countermeasure installation
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Measurement Units
Area Volume cm2 ＝ Square-centimeters (1.0 cm x 1.0 cm) cm3 ＝ Cubic-centimeters m2 ＝ Square-meters (1.0 m x 1.0 m) (1.0 cm x 1.0 cm x 1.0 cm or km2 ＝ Square-kilometers (1.0 km x 1.0 km) 1.0 milliliter) ha ＝ Hectares (10,000 m2) m3 ＝ Cubic-meters (1.0 m x 1.0 m x 1.0 m or 1.0 kiloliter ) L ＝ Liter (1,000 cm3) mL = milliliter (1/1,000 L)
Length Weight mm ＝ Millimeters g ＝ Grams cm ＝ Centimeters (cm ＝ 10 mm) kg ＝ Kilograms (1,000 g) m ＝ Meters (m ＝ 100 cm) ton ＝ Metric tone (1,000 kg) km ＝ Kilometers (Km ＝ 1,000 m)
Currency Time Rs ＝ Nepalese rupee s ＝ Second min ＝ Minutes (60 s) hr ＝ Hours (60 min)
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The Study on Disaster Risk Management for Narayangharh-Mugling Highway Main Report
THE STUDY ON DISASTER MANAGEMENT FOR NARAYANGHARH –MUGULING HIGHWAY
FINAL REPORT Volume II: MAIN REPORT
Table of Contents Location Map of the Study Area ...... i Definition of Terms for Risk Assessment of Road Slope Disasters ...... ii Acronyms/Abbreviations ...... iii Measurement Unit...... viii
Page
CHAPTER 1 INTRODUCTION...... 1-1 1.1 Background of the Study ...... 1-1 1.2 Objectives/ Activities/ Outputs of the Study...... 1-2 1.3 Study Area...... 1-3 1.4 Implementation Framework...... 1-4 1.4.1 Steering Committee...... 1-4 1.4.2 Counterpart Team ...... 1-5 1.4.3 Technical Working Group...... 1-5 1.4.4 Study Team ...... 1-7 1.5 Progress of the Study ...... 1-9 1.5.1 Phasing of the Study...... 1-9 1.5.2 Specific Work Items and Progress...... 1-9 1.6 Main Events in the Field Work ...... 1-11
CHAPTER 2 OVERVIEW OF SLOPE DISASTERS ON NARAYANGHARH – MUGLING HIGHWAY ...... 2-1 2.1 Natural Conditions Related to Slope Disaster in the Study Area...... 2-1 2.1.1 Topography and Geology ...... 2-1 2.1.2 Climate ...... 2-8 2.2 Social and Natural Condition...... 2-12
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2.2.1 Outline of the Study Area ...... 2-12 2.2.2 Social Condition of Kabilash Village ...... 2-17 2.2.3 Disaster Management in National Level ...... 2-20 2.2.4 Rainfall Feature in the Study Area...... 2-23 2.3 Road Slope Disasters on Narayangharh-Mugling Highway in 2003...... 2-30 2.3.1 The characteristics in 2003 disaster...... 2-30 2.3.2 Damages in 2003 disaster...... 2-33 2.4 Debris Flow Disaster at Ruwa Khola in 2003...... 2-36 2.4.1 Outline of Debris Flow Disaster...... 2-36 2.4.2 Associated Damages...... 2-37
CHAPTER 3 HAZARD AND RISK ASSESSMENT ON SLOPE DISASTERS ...... 3-1 3.1 Slope Disaster Types along Narayangharh – Mugling Highway ...... 3-1 3.1.1 Possible Slope Disasters along Narayangharh – Mugling Highway ...... 3-2 3.1.2 Classification of Slope Disasters on Narayangharh – Mugling Highway ...... 3-14 3.2 Stability Assessment of Selected Landslide Sites ...... 3-19 3.2.1 Selected Sites...... 3-19 3.2.2 Site Conditions...... 3-19 3.2.3 Study Results...... 3-21 3.2.4 Potential of Big Landslides along Highway ...... 3-30 3.3 Risk Assessment of Road Slope Disasters ...... 3-32 3.3.1 Outline of Risk Assessment...... 3-32 3.3.2 Workflow...... 3-34 3.3.3 Road Slope Assessment Sheet ...... 3-35 3.4 Results of Risk Assessment ...... 3-62 3.4.1 Narayangharh-Mugling Highway...... 3-62 3.4.2 Ruwa Khola/ Marsyangdi Hydro Power Plant ...... 3-77
CHAPTER 4 BASIC STRATEGY ...... 4-1 4.1 General...... 4-1 4.1.1 Policies on Formulation of Basic Strategy ...... 4-1 4.1.2 Identification of Current Potential Risk...... 4-1 4.1.3 Policy to Plan Basic Strategy...... 4-2 4.2 Additional Structural Measures ...... 4-4 4.2.1 Target Setting...... 4-4 4.2.2 Selected Sites for Preventive Structural Measures ...... 4-4
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4.2.3 Preliminary Design and Cost Estimation...... 4-5 4.2.4 Implementation Plan...... 4-9 4.3 Regular Maintenance and Quick Response ...... 4-14 4.3.1 Road Maintenance along with Annual Plan...... 4-14 4.3.2 Activities and of Maintenance and Requested Budget ...... 4-16 4.3.3 Recommendation on Road Maintenance Works...... 4-18 4.4 Maintenance of Sabo Facilities...... 4-20 4.4.1 Implementation organization...... 4-20 4.4.2 Major Maintenance Works of Sabo Dams...... 4-20 4.4.3 Flow of Maintenance Works of Sabo Dams ...... 4-21 4.4.4 Outline of Removal of Deposits ...... 4-22 4.4.5 Repair of Sabo Facilities...... 4-24 4.5 Road Early Information System...... 4-25 4.5.1 Purpose ...... 4-25 4.5.2 Target Area...... 4-25 4.5.3 Outline of the System ...... 4-25 4.5.4 Organization Formed to Operate the System...... 4-28 4.5.5 Cost and Economical Evaluation of the System...... 4-29 4.6 Disaster Mitigation Activities in Communities...... 4-31 4.6.1 Purpose ...... 4-31 4.6.2 Target Area...... 4-31 4.6.3 Outline of Disaster Mitigation Activities in Kabilash Village...... 4-31 4.6.4 Cost of the System and Economic Evaluation...... 4-36 4.7 Organization and Institutional Plan/Budget Planning...... 4-37 4.7.1 Organization in Charge...... 4-37 4.7.2 Necessary Expenditure...... 4-38 4.8 Evaluation of Basic Strategies ...... 4-40 4.8.1 Social & Environment ...... 4-40 4.8.2 Integrated Evaluation...... 4-40
CHAPTER 5 PILOTPROJECT I：ROAD EARLY INFORMATION SYSTEM...... 5-1 5.1 Method of Pilot Project I...... 5-1 5.1.1 Purpose of Road Early Information System ...... 5-1 5.1.2 Process of Pilot Project...... 5-1 5.2 Organization of Pilot Project I ...... 5-3 5.2.1 Formulation of the Committee ...... 5-3
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5.2.2 System Designing...... 5-8 5.2.3 Installation of Devices...... 5-23 5.2.4 Instruction of System Operation...... 5-26 5.3 Implementation of Pilot Project I...... 5-31 5.3.1 Operation of Road Early Information System...... 5-31 5.3.2 Traffic Closure Induced by Rock Mass Failure at 29km+850...... 5-32 5.3.3 Weather Condition during Pilot project...... 5-34 5.4 Evaluation of Pilot Project I...... 5-35 5.4.1 Summary of Evaluation...... 5-35 5.4.2 Evaluation of Project Output ...... 5-36 5.4.3 Evaluation of Project Purpose ...... 5-41 5.4.4 Evaluation of Overall Goal...... 5-42 5.4.5 Evaluation of Organization...... 5-43
CHAPTER 6 PIROT PROJECT II: DISASTER MITIGATION ACTIVITIES IN KABILASH VILLAGE ...... 6-1 6.1 Objective and Target Area of Pilot Project II...... 6-1 6.2 Items of Pilot Project II...... 6-2 6.3 Organization of Pilot Project II...... 6-3 6.4 Collaboration with Grassroots Activity...... 6-5 6.5 Implementation of Pilot Project II ...... 6-6 6.5.1 Hazard Mapping...... 6-6 6.5.2 Disaster Education...... 6-9 6.5.3 Early Warning/ Evacuation System ...... 6-14 6.5.4 Simple Structural Measures...... 6-19 6.5.5 Forestation Planning and Countermeasure Planning...... 6-22 6.6 Evaluation of Pilot Project II ...... 6-35 6.6.1 Summary of Evaluation...... 6-35 6.6.2 Evaluation of Project Output ...... 6-36 6.6.3 Evaluation of Project Purpose ...... 6-38 6.6.4 Evaluation of Overall Goal...... 6-39
CHAPTER 7 STRUCTURAL COUNTERMEASURES FOR RUWA KHOLA/MARSYANGDI HYDROPOWER PLANT...... 7-1 7.1 Concept and Design...... 7-1 7.1.1 Concept of Design ...... 7-1
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7.1.2 Design of Structural Countermeasures ...... 7-3 7.1.3 Construction Plan...... 7-6 7.1.4 Project Cost Estimation and Cost-Benefit Analysis ...... 7-8 7.2 Project Evaluation...... 7-9 7.2.1 Social and Environment...... 7-9 7.2.2 Comprehensive Evaluation...... 7-9
CHAPTER 8 TECHNICAL TRANSFER ...... 8-1 8.1 Technical Advice on Structural Measures...... 8-1 8.1.1 Background...... 8-1 8.1.2 Purposes...... 8-1 8.1.3 Outline of Technical Guide...... 8-2 8.2 Technical Transfer on Disaster Information System and Disaster Education...... 8-3 8.2.1 Disaster Information System ...... 8-3 8.2.2 Disaster Education...... 8-3
CHAPTER 9 CONCLUSION AND RECOMMENDATION ...... 9-1 9.1 Conclusion ...... 9-1 9.1.1 Risk Level of Narayangharh-Mugling Highway ...... 9-1 9.1.2 Basic Strategy Disaster Risk Management...... 9-2 9.1.3 Implementation Cost for Basic Strategy...... 9-3 9.1.4 Sabo Planning for Ruwa Khola ...... 9-4 9.1.5 Formulation of Implementation Organization ...... 9-4 9.2 Recommendation for Self-Supported Sustainability...... 9-6 9.2.1 Continuous Implementation of Basic Strategy ...... 9-6 9.2.2 Application of Basic Strategy for National Road Section ...... 9-6 9.2.3 Development of Disaster Information System ...... 9-6 9.2.4 Technical Advice on Countermeasure Works...... 9-8
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List of Figures Figure 1.2.1 Relationship between this Study and the Ultimate Goal...... 1-3 Figure 1.4.1 Implementation Framework of the Study ...... 1-4 Figure 2.1.1 Subdivision of the Himalaya...... 2-2 Figure 2.1.2 Generalized cross section of the Himalaya...... 2-2 Figure 2.1.3 Slope Gradient Map for CH 11 – CH 36 ...... 2-4 Figure 2.1.4 Slope Aspect Map for CH 11 – CH 36...... 2-4 Figure 2.1.5 Generalized Geological Map for CH 11 – CH 36...... 2-6 Figure 2.1.6 Contour Map of bedding planes of the Nawakot Complex ...... 2-7 Figure 2.1.7 Climatic Types in Nepal...... 2-9 Figure 2.1.8 Annual Rainfall in Nepal ...... 2-10 Figure 2.1.9 Maximum Air Temperature of Bharatpur Station ...... 2-11 Figure 2.2.1 Location of Study Area ...... 2-12 Figure 2.2.2 Administrative Chart of Kabilash VDC...... 2-18 Figure 2.2.3 Political Organization of Kabilash VDC ...... 2-18 Figure 2.2.4 Land-use Map of Kabilash VDC ...... 2-19 Figure 2.2.5 Disasters Risk Areas of Kabilash Village ...... 2-19 Figure 2.2.6 Rainfall stations in and around the study area...... 2-24 Figure 2.2.7 Rainfall Distribution on 31 July 2003 at Devghat station...... 2-25 Figure 2.2.8 Rainfall Intensity Curve for 31 July 2003 (Devghat Station) ...... 2-26 Figure 2.2.9 Daily Rainfall Pattern during 2006 Disaster...... 2-26 Figure 2.2.10 Observed hourly rainfall and predicted hourly rainfall on the rainfall of June 31, 2003 ...... 2-29 Figure 2.3.1 Hazard map for CH 10-36 of N-M Highway...... 2-32 Figure 2.3.2 Lives and Properties Lost in 2003 Disaster in Villages ...... 2-33 Figure 2.4.1 Conceptual Illustration of the 2003 Debris Flow Occurrence ...... 2-37 Figure 3.1.1 Flow of Slope Hazard/Risk Assessment ...... 3-1 Figure 3.1.2 Hazard Map for CH 10 – CH 36 of N-M Highway ...... 3-3 Figure 3.1.3 Geometric Classification of Road Slopes ...... 3-5 Figure 3.1.4 Strikes and Dips of Bedrock along the Highway...... 3-6 Figure 3.1.5 Schematic Illustration of Slope Failure – Debris Flow Succession ...... 3-7 Figure 3.1.6 Schematic Illustration of Slope Failure – Debris Flow Succession ...... 3-8 Figure 3.1.7 Schematic Illustration of Dip-Slip Slope ...... 3-9 Figure 3.1.8 Typical Slope Failure in between CH 22 – 22+500 ...... 3-10 Figure 3.1.9 Wedge-shaped Rock Slides forming a Slope Failure...... 3-10 Figure 3.1.10 North-facing Dip-slip Slope and Highway along Trishuli River ...... 3-11
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Figure 3.1.11 Schematic Illustration of Bedding-parallel Slip along Highway ...... 3-12 Figure 3.1.12 Typical Dip-slip Slope formed by Bedding-parallel slip of bedded rock ...... 3-12 Figure 3.1.13 Non-tectonic deformations of phyllites of the Nourpul Formation ...... 3-13 Figure 3.1.14 Schematic Illustration of Rock fall from Cut-Slope of Quartzite ...... 3-14 Figure 3.1.15 Schematic Illustrations of the Major Types of Landslide Movement ...... 3-15 Figure 3.1.16 Schematic Illustrations of slope hazard type in the Study ...... 3-18 Figure 3.2.1 Location of selected survey sites for Narayangharh-Mugling Highway ...... 3-19 Figure 3.2.2 Plan View and Cross Section of SL-1...... 3-22 Figure 3.2.3 Pipe Strain Measurement Records of BH-1, BH-3, and BH-4 ...... 3-23 Figure 3.2.4 Plan View and Cross Section of SL-2...... 3-25 Figure 3.2.5 Plan View and Cross Section of SL-3...... 3-27 Figure 3.2.6 Plan View and Cross Section of SL-4...... 3-29 Figure 3.3.1 Relation of Risk Indicators ...... 3-32 Figure 3.3.2 Estimation Structure of FRCDp...... 3-32 Figure 3.3.3 Estimation Structure of Annual Losses...... 3-33 Figure 3.3.4 Flow of Road Slope Assessment on N-M Highway ...... 3-34 Figure 3.3.5 Flowchart For Assessment of Risk and Feasibility of Structural Measures...... 3-35 Figure 3.3.6 Example of Assessment Sheet1 General Information...... 3-38 Figure 3.3.7 Calculation Procedure for FRCDp in Road Slope Assessment Sheet 2...... 3-40 Figure 3.3.8 Illustration for Searching Most Suitable Frequency Scores...... 3-41 Figure 3.3.9 Frequency Scores of Mountainside Slope...... 3-43 Figure 3.3.10 Frequency Scores of Crossing Stream ...... 3-44 Figure 3.3.11 Frequency Scores of Riverside Slope ...... 3-45 Figure 3.3.12 Road Slope Assessment Sheet 2-1: Potential Frequency of RCD (Mountainside Slope)...... 3-47 Figure 3.3.13 Road Slope Assessment Sheet 2-2: Potential Frequency of RCD (Crossing Stream)...... 3-48 Figure 3.3.14 Road Slope Assessment Sheet 2-3: Potential Frequency of RCD (Riverside Slope) ...... 3-49 Figure 3.3.15 Calculation Procedure of Potential Annual Loss ...... 3-50 Figure 3.3.16 Example of Road slope Assessment Sheet 3: Potential Disaster Magnitude and Annual Loss...... 3-51 Figure 3.3.17 Option Selection Proportion to N-M Highway Road Closure of Full Width.....3-57 Figure 3.3.18 Proportion of Three components of Average Traffic suspension Loss per vehicle [Rs/vehicle]...... 3-60 Figure 3.3.19 Road Slope Assessment Sheet 5: Disasters Record [Rs/vehicle]...... 3-61
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Figure 3.4.1 Potential Frequency of RCD of a site (FRCDp) with Hazard...... 3-63 Figure 3.4.2 Potential Annual Loss of a site (ALp) with Hazard...... 3-64 Figure 3.4.3 Potential Annual Loss (ALp) on N-M Highway by Slope Type at 2007 Value ...3-65 Figure 3.4.4 Potential Annual Loss (ALp) on N-M Highway by Loss Component at 2007 Value ...... 3-66 Figure 3.4.5 Risk Reduction by Existing Structural Measure...... 3-67 Figure 3.4.6 Location of Six (6) High Risk Mountainside Slopes where ALp is over 1.0 million ...... 3-70 Figure 3.4.7 Location of Six (6) High Risk Crossing streams where ALp is over 1.0 million 3-71 Figure 3.4.8 Processing of Risk Level Indicators of a Road Section...... 3-72 Figure 3.4.9 Intensity of RCD (IRCD)...... 3-75 Figure 3.4.10 Intensity of Annual Loss (IALP)...... 3-76 Figure 3.4.11 Flow of Risk Estimation for Ruwa Khola/ Marsyangdi Hydro Power Plant .....3-77 Figure 4.1.1 Concept Formulation of Disaster Risk Management...... 4-1 Figure 4.1.2 Components of the Basic Strategy and Risk Management ...... 4-2 Figure 4.2.1 Locations of the Selected Sites to Deliberation of Additional Countermeasure....4-5 Figure 4.2.2 Procedure of Shotcrete Crib Work Construction ...... 4-11 Figure 4.2.3 Procedure of Shotcrete Crib Work with Rock Bolt Construction ...... 4-11 Figure 4.2.4 Procedure of Rock Fall protection Net Work Construction ...... 4-11 Figure 4.2.5 Overall Construction Schedule for Package I and III ...... 4-12 Figure 4.2.6 Overall Construction Schedule for Package II...... 4-13 Figure 4.3.1 Organization of Division Roads Office, Bharatpur...... 4-15 Figure 4.3.2 Flow of Preparation of Annual Road Maintenance Plan on Sediment Related Disasters...... 4-16 Figure 4.3.3 Flow of Emergency Works...... 4-19 Figure 4.4.1 Flow of Maintenance Works for Sabo Dams ...... 4-22 Figure 4.4.2 Location of Sabo Dams Needed to Remove Deposits ...... 4-23 Figure 4.4.3 Conceptual Illustration of Functional Recovery for Sabo Dam...... 4-23 Figure 4.4.4 Result of Inventory Survey on Facility of Disaster Preventive Works ...... 4-24 Figure 4.5.1 Target Areas for Risk Management by Road Early Information System...... 4-25 Figure 4.5.2 Schematic Chart of Formulated Road Early Information System ...... 4-26 Figure 4.6.1 Locations of Wards in Kabilash Village...... 4-31 Figure 4.6.2 Organization of Disaster Mitigation Activities in Kabilash Village ...... 4-32 Figure 4.6.3 Information System for Early Warning and Evacuation ...... 4-35 Figure 4.7.1 Implementation Organization for Basic Strategies ...... 4-37 Figure 5.1.1 Process of Execution of Pilot Project...... 5-1
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Figure 5.2.1 Committees and Implementation Organizations for Road Early Information System and Disaster Mitigation Activities in Kabilash Village...... 5-4 Figure 5.2.2 Location of Raingauge...... 5-8 Figure 5.2.3 Schematic Chart of Road Early Information System...... 5-9 Figure 5.2.4 Web page image...... 5-13 Figure 5.2.5 Graph of Rainfall and Threshold of Warning Level ...... 5-16 Figure 5.2.6 Image of Display and Graph Layout...... 5-16 Figure 5.2.7 Image of Display on Rainfall and Traffic Obstacle Information ...... 5-18 Figure 5.2.8 Image of Display Layout ...... 5-18 Figure 5.2.9 Dimensional Outline of Notice Board (Rainfall Information)...... 5-19 Figure 5.2.10 Dimensional Outline of Notice Board (Traffic Information)...... 5-20 Figure 5.2.11 Display of Notice Board ...... 5-21 Figure 5.2.12 General Flow of Road Early Information System ...... 5-22 Figure 5.2.13 General Organization of Drill Work ...... 5-27 Figure 5.2.14 Scenario of Drill...... 5-28 Figure 5.3.1 The Slope where rock mass failure occurred...... 5-33 Figure 5.3.2 Daily rainfall data by Automatic Raingauges ...... 5-34 Figure 5.4.1 2nd Committee Meeting of Chitwan District Disaster Management Partnership Committee on November 2008 in Royal Century Hotel, Narayangharh...... 5-43 Figure 5.4.2 Conceptual Image on Information Flow for the System Operation...... 5-46 Figure 6.3.1 Disaster Mitigation Organization in Kabilash Village...... 6-3 Figure 6.5.1 Kabilash Village Hazard Map (Satellite Image Base) Ward No.1 ...... 6-7 Figure 6.5.2 Kabilash Village Hazard Map (Topographic Map Base) Ward No.1...... 6-8 Figure 6.5.3 Disaster Education for Leaders...... 6-10 Figure 6.5.4 Disaster Education for Students...... 6-13 Figure 6.5.5 Disaster Education for Villagers ...... 6-14 Figure 6.5.6 System of Information Transmission under Heavy Rainfall in Kabilash Village 6-15 Figure 6.5.7 Rain Gauge (Left) and Computer System (Right) in Kabilash Village...... 6-16 Figure 6.5.8 Daily rainfall data by Automatic Raingauge...... 6-19 Figure 6.5.9 Simple Slope Protection Works at Crossing Stream of N-M Highway CH 11km+500m...... 6-20 Figure 6.5.10 Construction Situation of Simple Slope Protection Work (June, 2008)...... 6-21 Figure 6.5.11 After Construction of Simple Slope Protection Work (August, 2008)...... 6-21 Figure 6.5.12 (1) Location Map of Reforestation site on Ward 1 ...... 6-25 Figure 6.5.12 (2) Location Map of Reforestation site on Ward 2 ...... 6-26 Figure 6.5.12 (3) Location Map of Reforestation site on Ward 3 ...... 6-27
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Figure 6.5.12 (4) Location Map of Reforestation site on Ward 4 ...... 6-28 Figure 6.5.12 (5) Location Map of Reforestation site on Ward 5 ...... 6-29 Figure 6.5.12 (6) Location Map of Reforestation site on Ward 6 ...... 6-30 Figure 6.5.12 (7) Location Map of Reforestation site on Ward 7 ...... 6-31 Figure 6.5.12 (8) Location Map of Reforestation site on Ward 8 ...... 6-32 Figure 6.5.12 (9) Location Map of Reforestation site on Ward 9 ...... 6-33 Figure 6.6.1 Situation of Simple Slope Protection Work (November 2008)...... 6-37 Figure 7.1.1 Conceptual Illustration of the Effectiveness of Debris Flow Guide Concrete Wall ...... 7-2 Figure 7.1.2 Standard Section of Debris Flow Guide Concrete Wall...... 7-6 Figure 7.1.3 Construction of Guide Concrete Wall...... 7-7 Figure 7.1.4 Construction Schedule for Guide Concrete Wall ...... 7-8
List of Tables Table 1.4.1 Members of the Steering Committee...... 1-5 Table 1.4.2 Members of C/P Team...... 1-5 Table 1.4.3 Members of Technical Working Group ...... 1-6 Table 1.4.4 Staff for Establishment of Basic Strategy Programs ...... 1-6 Table 1.4.5 List of JICA Study Team Members ...... 1-7 Table 1.5.1 Phasing of the Study...... 1-9 Table 1.5.2 Study Items and Progress ...... 1-10 Table 1.6.1 Outline of Events in the Field Work...... 1-11 Table 2.1.1 Strata and Rocks in Study Area ...... 2-5 Table 2.1.2 General Geology of Road Slopes (CH 10 – CH 36)...... 2-8 Table 2.2.1 Household and Population in the Study Area...... 2-13 Table 2.2.2 Economic Activities in the Study Area...... 2-13 Table 2.2.3 Estimated Annual Income per Households in Study Areas ...... 2-14 Table 2.2.4 Estimated Cultivated Land and Irrigation Status in Study Areas ...... 2-14 Table 2.2.5 Cropping Pattern in the Study Area...... 2-15 Table 2.2.6 Estimated Cropped Areas and Yield Rates ...... 2-15 Table 2.2.7 Drinking Water Situation...... 2-15 Table 2.2.8 Literacy Status in the Study Area ...... 2-16 Table 2.2.9 Educational and other Service Institutions Available in Study Areas...... 2-16 Table 2.2.10 Heritage and Monuments to be Protected in Study Areas ...... 2-17 Table 2.2.11 Manpower of DWIDP ...... 2-22 Table 2.2.12 Road Maintenance Expenditure for N-M Highway for Fiscal Year 2006/2007 ..2-23
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Table 2.2.13 Return Periods of Each Type of Rainfall Amounts...... 2-28 Table 2.2.14 Warning Levels by the Modified Rainfall Amounts...... 2-28 Table 2.3.1 Lives and Properties Lost in Villages during 2003 & 2006 Disasters...... 2-33 Table 2.3.2 Properties Lost on N-M Highway by 2003 Disaster ...... 2-34 Table 2.3.3 Debris Deposited on N-M Highway in 2003 Disaster and CDRO’s Actions ...... 2-34 Table 2.3.4 CDRO’s Rehabilitation Works after 2003 Disaster ...... 2-35 Table 2.3.5 CDRO’s Slope Stabilization Works after 2003 Disaster and their Locations...... 2-35 Table 3.1.1 Slope Type Classification with Chainage...... 3-6 Table 3.1.2 Classification and Characteristics of Slope Hazard Type in the Study...... 3-18 Table 3.2.1 Condition of Selected Sites ...... 3-20 Table 3.2.2 Evaluation of Landslide Hazard Potential for SL-1, SL-2, SL-3 and SL-4...... 3-31 Table 3.3.1 Items in the Assessment Sheet for Risk and Feasibility of Structural Measures...3-36 Table 3.3.2 Screening Criteria...... 3-37 Table 3.3.3 Highly Affecting Factor Items for RCD...... 3-42 Table 3.3.4 Example of Average CEM (Philippines National Highway)...... 3-46 Table 3.3.5 Definition of length of road closure section of a RCD...... 3-52 Table 3.3.6 Composition of Potential Loss of a RCD ...... 3-52 Table 3.3.7 Formula and Unit Cost for Potential Reopening Cost...... 3-53 Table 3.3.8 Formula and Unit Value for Potential value of Human Lives Lost ...... 3-54 Table 3.3.9 Formula and Unit Value for Potential Value of Vehicle Loss ...... 3-55 Table 3.3.10 Formula and Unit Value for Potential Value of Vehicle Loss ...... 3-55 Table 3.3.11 Composition of Average Suspension Loss per Vehicle...... 3-57 Table 3.3.12 Formula and Unit Value for Average Waiting Loss per Vehicle ...... 3-58 Table 3.3.13 Formula and Unit Value for Average Detour Loss per Vehicle ...... 3-58 Table 3.3.14 Formula and Unit Value for Average Cancellation Loss per Vehicle ...... 3-59 Table 3.4.1 Summary of Potential annual Loss (ALp) and ALp without Structural Measures (ALpom) ...... 3-68 Table 3.4.2 Twelve High Risk Sites where ALp is over 1.0 Million...... 3-69 Table 3.4.3 Outline of Risk along N-M Highway ...... 3-74 Table 3.4.4 Loss by disaster on 31st July in 2007 Price (Tentative) ...... 3-78 Table 4.1.1 Risk before 2003 and At Present ...... 4-2 Table 4.2.1 Classification of Risk Level by Alp as of 2007...... 4-4 Table 4.2.2 Selected Sites of Preventive Structural Measures ...... 4-4 Table 4.2.3 Summary of Two Crossing Stream Ongoing Sabo Works by DWIDP...... 4-6 Table 4.2.4 Selected Sites for Implementing Preventive Structural Countermeasure...... 4-8 Table 4.2.5 Selected Sites and Proposed Structural Measures for Each Location ...... 4-9
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Table 4.2.6 Arrangement of Selected Sites for Implementation...... 4-10 Table 4.3.1 Planned Maintenance Works for N-M Highway ...... 4-17 Table 4.3.2 Cost and Benefit of Maintenance and Emergency Works ...... 4-18 Table 4.3.3 Sites Need Attention in Seasonal inspection ...... 4-18 Table 4.4.1 Sabo Dams Needed to Remove Deposits ...... 4-22 Table 4.5.1 Devices Composed of the System ...... 4-26 Table 4.5.2 Contents of Road Early Information ...... 4-27 Table 4.5.3 Threshold of Early Warning by Modified Rainfall Amount...... 4-27 Table 4.5.4 Cost of Road Early Information ...... 4-30 Table 4.5.5 Benefit of Road Early Information System ...... 4-30 Table 4.6.1 Role and Activities of Teams for Disaster Management for Kabilash Village ...... 4-33 Table 4.6.2 Threshold of Early Warning by Modified Rainfall Amount...... 4-35 Table 4.6.3 Cost of Early Warning/Evacuation System ...... 4-36 Table 4.7.1 Necessary Expenditure of Division Road Office, Bharatpur...... 4-38 Table 4.7.2 Necessary Expenditure of MN Water-induced Disaster Prevention Office, DWIDP ...... 4-39 Table 4.7.3 Necessary Expenditure of District Police Office, Chitwan ...... 4-39 Table 4.7.4 Necessary Expenditure of Kabilash Village ...... 4-39 Table 4.8.1 Deliberation and Points of Social/Environmental Consideration...... 4-40 Table 4.8.2 Integrated Evaluation of Basic Strategies...... 4-41 Table 5.2.1 (1) Committee Members for the Pilot Projects...... 5-5 Table 5.2.1 (2) Implementation Organization Members for Road Early Information System...5-6 Table 5.2.1 (3) Implementation Organization Members for Disaster Mitigation Activities in Kabilash Village...... 5-7 Table 5.2.2 Method of Data Collection (Automatic Raingauge)...... 5-9 Table 5.2.3 Method of Data Collection (Manual Raingauge) ...... 5-9 Table 5.2.4 Threshold of Early Warning by Modified Rainfall Amount (Draft)...... 5-10 Table 5.2.5 Devices of the System ...... 5-11 Table 5.2.6 Content of Warning Information ...... 5-12 Table 5.2.7 Information on Traffic Obstacle ...... 5-12 Table 5.2.8 Information in the image ...... 5-14 Table 5.2.9 Specification of Graph...... 5-15 Table 5.2.10 Information Collected by DPO...... 5-17 Table 5.2.11 Display Related to Rainfall Information...... 5-17 Table 5.2.12 Information of Traffic Obstacle...... 5-17 Table 5.2.13 Information in Notice Board ...... 5-21
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Table 5.2.14 Role for each organization on Drill on June 26th...... 5-27 Table 5.2.15 Process of Drill in Kabilash Village ...... 5-29 Table 5.3.1 Staff of DPO Unit...... 5-31 Table 5.3.2 Staff of DRO Unit...... 5-31 Table 5.3.3 Uploading Status for Road Early Information System in DPO Unit...... 5-31 Table 5.3.4 Uploading Status for Road Early Information System in DRO Unit ...... 5-32 Table 5.4.1 Summary of Evaluation for Pilot Project I: Road Early Information System ...... 5-35 Table 5.4.2 Result of Hearing for DOR, DPO and Kabilash VDC after Joint Drill...... 5-36 Table 5.4.3 Result of Hearing for Kabilash Villager after Joint Drill ...... 5-36 Table 5.4.4 (1) Evaluation for Road Early Information System during the Pilot Project (1)...5-38 Table 5.4.4 (2) Evaluation for Road Early Information System during the Pilot Project (2)...5-39 Table 5.4.5 Evaluation for Early Warning/ Evacuation System for Kabilash Village during the Pilot Project ...... 5-40 Table 5.4.6 Result of Research on Road Early Information System in June, 2008...... 5-41 Table 5.4.7 Result of Research on Road Early Information System in August, 2008...... 5-41 Table 5.4.8 Evaluation of Organization on Pilot Project...... 5-44 Table 6.1.1 Objective and Target Area of Disaster Mitigation Activities in Kabilash Village ...6-1 Table 6.2.1 Work Stage and Inputs for the Water-Induced Disaster Management in Kabilash Village...... 6-2 Table 6.3.1 Member of Early Warning/ Evacuation Team ...... 6-4 Table 6.3.2 Member of Disaster Education/ Hazard Map Team ...... 6-4 Table 6.3.3 Member of Simple Structural Measure/ Forest Plantation Team...... 6-4 Table 6.4.1 Collaborated Contents with Grassroots Activity ...... 6-5 Table 6.5.1 Specification of the Hazard Map...... 6-6 Table 6.5.2 Major Content in Education Material...... 6-9 Table 6.5.3 Program of Disaster Education for Leaders ...... 6-11 Table 6.5.4 Syllabus of Disaster Education for Students (1 Day Study)...... 6-12 Table 6.5.5 Syllabus of Disaster Education for Villagers (Half Day Study) ...... 6-12 Table 6.5.6 Implemented Schedule of Disaster Education for Students ...... 6-12 Table 6.5.7 Implemented Schedule of Disaster Education for Villagers...... 6-13 Table 6.5.8 Threshold of Early Warning by Modified Rainfall Amount (Draft)...... 6-16 Table 6.5.9 Participants’ Role on Early Warning / Evacuation System (Draft)...... 6-16 Table 6.5.10 Action Flow of the System under the Heavy Rainfall (Draft)...... 6-17 Table 6.5.11 Staff of Kabilash VDC...... 6-18 Table 6.5.12 Uploading Status for Road Early Information System in Kabilash VDC ...... 6-18 Table 6.5.13 Required Procurement Material for the Pilot Projects...... 6-20
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Table 6.5.14 List of Reforestation Site...... 6-23 Table 6.5.15 List of Nursery Site ...... 6-24 Table 6.5.16 List of Simple Countermeasure Implementation Site...... 6-34 Table 6.6.1 Summary of Evaluation for Pilot Project II: Disaster Mitigation Activities in Kabilash Village...... 6-35 Table 7.1.1 Unit Weight...... 7-3 Table 7.1.2 River Conditions...... 7-3 Table 7.1.3 Slope Conditions ...... 7-3 Table 7.1.4 Standard Stability Condition ...... 7-4 Table 7.1.5 Total Quantity of the Work ...... 7-6 Table 7.1.6 Results of Cost Benefit Analysis ...... 7-8
The figures and the tables in the report which their references are not described were prepared by the JICA Study Team.
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CHAPTER 1
INTRODUCTION
1.1 Background of the Study
In Nepal, a lot of disasters have occurred due to adverse natural conditions such as steep topography, fragile geology, heavy rainfalls during monsoon season, and earthquakes that occur intermittently. The roads in the mountainous areas are prone to frequent traffic blockade due to slope disasters. Narayangharh-Mugling Highway (hereafter referred to as “N-M Highway”), which is approximately 36 km, had been subjected to more than 20 serious failures such as slides and heavy debris flows that washout bridges. Severe damages have occurred along this road section due to heavy rains on 30th July 2003. This disaster affected the domestic industry and the logistics due to damaged roads which became impassable for a long duration. It also degraded the operation rates (40-50%) near Marsyangdi Power Plant at Ruwa Khola, 4 km west of Mugling. The N-M Highway is regarded as the most important road section connecting Kathmandu with India. Therefore, any traffic interruption paralyzes logistics, and cause catastrophic damage to the economy causing supply shortage and inflation in Nepal. It is noted that additional sabo facilities in Marsyangdi Power Plant are vital for the sustainable supply.
Well organized investigation and consequent preparation of basic plans is absolutely necessary for defining medium to long-term policy against slope disasters. The Government of Nepal (hereafter referred to as “GON”) had requested assistance from the Government of Japan for carrying out study on the technical issues.
In response to the request from the GON for the technical cooperation, the Government of Japan decided to conduct “The Study on Disaster Risk Management for Narayangharh-Mugling Highway” (hereafter referred to as “the Study”). Accordingly, the Japan International Cooperation Agency (hereinafter referred to as “JICA”), the official agency responsible for the implementation of the technical cooperation programs of the Government of Japan, dispatched a preliminary study team to Nepal and agreed to the related Scope of Work (S/W) and Minutes of Meeting (M/M) held on 31st January, 2007. It was decided that the Study be conducted from July 2007 to February 2009, in accordance the S/W and the M/M.
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1.2 Objectives/ Activities/ Outputs of the Study
The objectives of the Study are as shown in Figure 1.2.1:
1) To formulate the basic strategy on disaster risk management for the N-M Highway and to confirm the validity of the corresponding disaster management project for the target area
2) To transfer the technology to the responsible and implementing counterpart organizations (hereinafter referred to as “the C/P”) which are the Department of Water Induced Disaster Prevention, Ministry of Water Resources (hereafter referred to as “DWIDP”) and the Department of Roads, Ministry of Physical Planning and Works (hereafter referred to as “DOR”)
3) To formulate structural measures for Marsyangdi Hydro Power Plant in Ruwa River
The major activities and specific outputs of the Study are:
(I) To prepare a hazard map and assess the risks of the water-induced disaster on N-M Highway, and Ruwa River/Marsyangdi hydro power house
(II) To prepare the basic strategy for the water-induced disaster management for N-M Highway
(III) To implement the Feasibility Study (hereinafter referred to as F/S) for basic strategies of the water-induced disaster management for N-M Highway and structural measure for Ruwa River/Marsyangdi hydro power house
(IV) To execute pilot projects to confirm the appropriateness of disaster management procedure
(V) To transfer technology and knowledge of disaster management to the C/P, related organizations and communities
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Ultimate goal Improvement of safety and Application to credibility of the target area nationwide Future Future Implementation of Basic Strategy for Risk Management
Main activities V Transfer of technology and knowledge through seminars, workshops, etc.
y
I II III Preparation Formulation of
This stud Feasibility study of hazard Basic Strategy for map risk management, consideration of IV communities Pilot projects
Figure 1.2.1 Relationship between this Study and the Ultimate Goal
The results that will be obtained from this study can be applied to other important road sections/areas which are potentially affected by water-induced disasters such as the N-M Highway and neighboring areas and Ruwa River.
1.3 Study Area
The Study covers the following areas (Refer to the location map in the first page of this study):
(a) The N-M Highway and neighboring area (Road length: around 36 km, Residents in the vicinity: around 23,000)
(b) The Ruwa River basin beside the Marsyangdi Hydro Power Plant (Attachment area: around 2.69 km2, Residents in the vicinity: around 2,500)
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1.4 Implementation Framework
In accordance with the M/M on S/W of the Study dated 31st January 2007, the implementing organization established composed of JICA Headquarters and Nepal Office as the client, the DWIDP and the DOR as the Nepali C/Ps, and the JICA Study Team (hereafter referred to as “the Team”). Structure of implementation framework is shown in Figure 1.4.1.
DOR DWIDP JICA Head Quarter (Department of Water (Department of Roads) Induced Disaster Prevention) JICA Nepal Office JICA Experts
Steering Committee
Approval/Decision/Recommendation
Advice Technical Working Group and Working Teams
Proposal/Report
Counterpart Team JICA Study Team
Figure 1.4.1 Implementation Framework of the Study
The Steering Committee (hereafter referred to as “the S/C”) was set up to manage the implementation of the Study in accordance with the M/M. Additionally technical working groups (TW/G) or working teams for specific tasks are formulated to execute required tasks.
1.4.1 Steering Committee
The S/C has been set up to provide the Study with managerial instructions, evaluations reports, and other related information.
The 1st S/C meeting was held on 9th August 2007 to approve the plan of operation of the Study in accordance with the Inception Report. Meeting regarding the progress report was held on 4th November 2007 however, the chairperson was not available during said date. Hence, the official 2nd S/C was held on 27th November 2008 to discuss sustainable implementation of basic
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The S/C was chaired by the Secretary of the Ministry of Water Resources. The organization listed in Table 1.4.1 below has been designated by the GON. In addition to the committee members, the Nepali side invited the related donor agencies as observers, such as the World Bank and Asian Development Bank during the committee’s meetings.
Table 1.4.1 Members of the Steering Committee Name Position Organization Shankar Prasad Koirala Chairman Secretary, MOWR Narayan Prasad Vice-Chairman DG, DWIDP Bhattarai Ramesh Raj Bista Vice-Chairman DDG, DOR Shiv Chandra Jha Member DMD, NEA Ramesh Tuladhar Member Sabo Section Chief, DWIDP Shanumukesh Amatya Member (Successor for Landslide Section Chief, DWIDP Mr. Tuladhar) Selecting Observer World Bank Nogendra Sapkota Observer Social Environment Officer, ADB Yusuke Tsumori Observer ARR, JICA/Nepal
1.4.2 Counterpart Team
C/P Team assigned five engineers to conduct the study jointly with the Team as shown in the Table 1.4.2.
Table 1.4.2 Members of C/P Team Name Position Present Status Ramesh Tuladhar Team Leader Superintending Hydrogeologist, DWIDP Shanumukesh Amatya Team Leader (Successor Engineering Geologist, DWIDP for Mr. Tuladhar) Shree Kamal Dwivedi Member Engineering Geologist, DWIDP Bed Kantha Yogol Member Engineer, DRO Rajendra Raj Sharma Member Chief DOR, DRO
1.4.3 Technical Working Group
On the initiative of the C/P, a (TW/G) composed of nine engineers was proposed to be set up, in view of the objectives of the Study. The TW/G aims to assist the S/C in organizing regular coordination meetings with the Team, and support the smooth implementation of the Study. The TW/G was composed of designated representatives from DWIDP, DOR, and related organizations.
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The 1st TW/G meeting was held on 10th August 2007with engineers of head office of DWIDP and DOR.
The 2nd TW/G meeting was held on 13 September 2007 mainly with engineers of Mugling-Narayangharh Water Induced Disaster Prevention Project (hereinafter described as “MNWIDPP”) and District Road Office (DRO) Bharatpur, Chitwan. The participants can be considered members of TW/G who are shown in the Table 1.4.3.
Table 1.4.3 Members of Technical Working Group Name Position Present Status Ramesh Tuladhar Team Leader Sabo Chief, DWIDP Shanumukesh Amatya Team Leader (Successor Landslide Section Chief, DWIDP for Mr. Tuladhar) Shree Kamal Dwivedi Member Engineering Geologist, DWIDP Saroj Pandit Member PM, MNWIDPP Yogendra Mishara Member Engineer, MNWIDP Basanta Raj Paudel Member Engineer, MNWIDP Krishna Raj Pathak Member Engineer, MNWIDP Rajendra Raj Sharma Member Chief DOR, DRO Uma Kant Member Engineer, DOR, DRO
From May 2008, Working Teams for establishment of the basic strategy programs has been formulated as shown in Table 1.4.4.
Table 1.4.4 Staff for Establishment of Basic Strategy Programs Program Study Team DWIDP DOR Road Maintenance M. Eto B. Subedi, ＋α M. Mori Quick Response M. Eto B. Subedi, ＋α M. Mori Sabo Facility Maintenance M. Eto R. Tuladher M. Mori (S. Amatya) P. Yang S. Pandit J. Kitagawa K.R. Pattack, ＋α District Disaster Management by M. Eto R. Tuladhar B.Yogol Stack holder partnership M. Mori (S. Amatya) R.R.Sharma - Road Early Information System H. Ono K. Dwivedi B.Chapagain - Disaster Mitigation Activities in Y. Numata K. R. Pathak, ＋α District Road Communities (pilot project in T. Matuo Office engineer Kabilash Village) Preparation of Technical Guide M. Eto R. Tuladhar B.Yogol M. Mori (S. Amatya) R.R.Sharma P. Yang S.Pandit B.Chapagain, J. Kitagawa K.R.Pathak, ＋α ＋α
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1.4.4 Study Team
The Team, composed of 12 engineers as shown in Table 1.4.5, implemented the Study in accordance with the plan of operation outlined in the IC/R.
Table 1.4.5 List of JICA Study Team Members Position/Specialties Role assignment 1. General management of the Study 2. Coordination with the C/P and related organization Masatoshi ETO 3. Basic policy and plans of operation
4. Management of local contractors Team leader/ control of 5. Technical seminars and workshops soil erosion and rivers 6. General evaluation and recommendation 7. Preparation of reports 1. Proxy for the leader 2. General management of the Study Takashi SUGIMOTO 3. Coordination with the C/P and related organization 4. Basic policy and plans of operation Co-team leader / control 5. Management of local contractors of soil erosion and rivers 6. Technical seminars and workshops 7. General evaluation and recommendation 8. Preparation of reports Mikihiro MORI 1. Formulation of basic policy 2. Plan of pilot projects Road (disaster) 3. Monitoring and evaluation of slides management 4. Implementation of pilot projects 1. Topological and geological surveys Kenichi TANAKA 2. Field reconnaissance of slides 3. Preparation of a comprehensive hazard map Geology 4. Management of geological survey 1. Data collection and analysis of social condition, land use, etc. Hiroyuki ONO 2. Risk assessment 3. Feasibility study Social/economy 4. Selection of pilot project sites 5. Plan of pilot projects 6. Evaluation of pilot projects Takeshi KUWANO 1. Review on environmental/social situation 2. Feasibility study Environmental/social 3. Preparation for stakeholder meeting consideration 1. Collection and analysis of meteorological data Khadananda LAMSAL 2. Analysis of relationship between rainfall and disasters 3. Preparation of criteria for alert and traffic control Hydrology 1. Cost estimation Puchai YANG 2. Feasibility study 3.Technical advice Cost estimation
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1. Project coordination Satoru NODA 2. Assistance of members
Project coordinator 1. Preparation of road early information system Yusuke NUMATA 2. Preparation of early warning/ evacuation system
Disaster Information management Tamaki MATSUO 1. Preparation and facilitation of the pilot project of disaster management in Kabilash Village Disaster management Environmental/Social Consideration Junichi KITAGAWA 1. Technical advice for structural measures 2. Preparation of technical guide Structural countermeasure works
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1.5 Progress of the Study
1.5.1 Phasing of the Study
The Study has been implemented for around 20 months, form 5th July 2007 to 27th February 2009. Progress schedule and specific work items related to the Study are shown in Table 1.5.1.
Table 1.5.1 Phasing of the Study Phase Major Study Theme Period Phase I - Risk assessment for the target area, July 2007 – November 2007 - Geological survey, - Formulation of Basic Strategy Phase II - Implementation of Feasibility Study (F/S), December 2007 – June 2008 - Pilot projects, and monitoring of slopes Phase III - Execution Pilot project July 2008 – November 2008 - Monitoring and evaluation in the monsoon season
1.5.2 Specific Work Items and Progress
Progress schedule and specific work items on the project are shown in Table 1.5.2.
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Table 1.5.2 Study Items and Progress 2007 2008 2009 Schedule 78910111212345678910111212 Year First Year Second Year Phase Phase I Phase II Phase III Activities Items 1st Field Work 2nd Field Work 3rd Field Work 4th Field Work Inception Report (IC/R) Progress Report (P/R) interim report (IT/R) Report Draft Final Report (DF/R) Evaluation Report (E/R) Final Report (F/R) Phase I 1st Work in Japan 【1】 Data collection and analysis in Japan 【2】 Review of policies; preparation of the work plan and methodology 【3】 Preparation of the Inception Report (IC/R) 1st Field Work 【4】 Meeting on the Inception Report 【5】 Data collection 【6】 Field reconnaissance 【7】 Geological survey 【8】 Review of existing plans and studies, organizations, and legal systems 【9】 Analysis of relationship between rainfall and disasters 【10】 Definition of words on slope disasters 【11】 Analysis of data and information 【12】 Technical advice on structural measures 【13】 Disaster risk assessment in the study area 【14】 Formulation of a comprehensive hazard map 【15】 Concept formulation of the disaster risk management 【16】 Formulation of Basic Strategy 【17】 Preparation for pilot projects and monitoring of slides 【18】 Preparation/explanation/discussion of the Progress Report (P/R) Phase II 2nd Field Work 【19】 Selection of the sites 【20】 Implementation of feasibility study (F/S) 【21】 Preparation/explanation/discussion of the interim report (IT/R) 3rd Field Work 【22】 Pilot project and monitoring of slides 【23】 Technical advice on structural measures 【24】 Preparation/explanation/discussion of the Draft Final Report (DF/R) Phase III 4th Field Work 【25】 Evaluation for pilot project and monitoring of slides 【26】 Technical advice on structural measures 【27】 Preparation/explanation/discussion of Evaluation Report (E/R) 2nd Work in Japan 【28】 Preparation/submission of the Final Report (F/R) Field work 1st Work in Japan 2nd Work in Japan
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1.6 Main Events in the Field Work
Main events in the field work were as follows.
1) 1st steering committee meeting 2) 1st technical working group meeting 3) Joint inspection for risk assessment 4) 1st seminar/workshop 5) 2nd technical working group meeting 6) Meeting on the progress report 7) 2nd seminar/workshop 8) 1st Chitwan district disaster management partnership committee 9) 3rd seminar/workshop for pilot project 10) 2nd Chitwan district disaster management partnership committee 11) Advisory committee 12) 2nd Steering committee meeting 13) Reporting session
Through these events, discussion on the study policy and study results, decision of policy, or technical transfer was carried out. Outline of these events are shown in the Table 1.6.1.
Table 1.6.1 Outline of Events in the Field Work Event/ Date Venue/Outline Phase I 1st Steering committee At Secretary’s Office, MOWR meeting 1. Explanation of plan of operation 9th August 2007 2. Recommendation and Discussion by members N.P.Bhattarai, R.R.Bista, N.Sapkota, S.C. Jha 3. Decision: Approval of objective, 1st Technical Working At meeting room, DWIDP, Pulchwok group meeting 1. Explanation of methodology of the study and definition of 10th August 2007 terminology related with landslide 2. Discussion on the method of the Study 3. Understanding of the methodology and terminology Joint inspection for risk Risk assessments for 305 sites (134 mountainside slopes, 78 crossing assessment streams, and 93 river side slopes) on the N-M Highway Late August 2007 At N-M Highway Joint assessment survey 1. Inspection for ten selected sites for implementing preventive and inspection for high risk measures sites 2. Discussion in the field 12th September 2007 3. Selection for 10 sites structural measure should be planed -11km+500 (Khare khola) and 12km+600(Das Khola) was canceled because of additional sabo dam is constructing.
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Event/ Date Venue/Outline 1st seminar/ workshop At the Meeting Room of Global Hotel, Bharatpur 13th September, 2007 -Presentation and discussion on following subjects a) General issues on landslide in Nepal b) Outline of the Study c) Relationship between debris flow and rainfall d) Plan of pilot project 2nd technical working Discussion on following subjects and approval group meeting 1. Sites for preventive countermeasure; agreed as the decision in the 13th September, 2007 field 2. Policy on the pilot project; agree generally as planned by the Team Meeting on Progress Reported by the Team on the progress of the study and given Report recommendation and requirement by the chairman and members. 6th November, 2007 Phase II 2nd Seminar/ Workshop Held in 2nd at Hotel Himalaya’s Seminar Hall. 22nd February, 2008 - Sessions in the seminar Session I: Opening Session II: System and Activities on Sediment-Related Disasters Session III: Risk Evaluation for Slope Hazard in N-M Highway Session IV: Basic Strategy on Disaster Risk Management 1st Chitwan district disaster Discussion on management partnership - road early warning system on N-M highway committee - disaster management activities in Kabilash Village 9th June 2008 Seminar/workshop for Held in Royal Century the Business Hotel Narayangharh pilot projects - road early warning system on N-M Highway 26th June 2008 - disaster management activities in Kabilash Village Phase III 2nd Chitwan district Held in Royal Century the Business Hotel Narayangharh disaster management - road early warning system on N-M Highway partnership committee - disaster management activities in Kabilash Village 20th November, 2008 Advisory committee At meeting room, DWIDP 24th November, 2008 - road early warning system on N-M Highway - disaster management activities in Kabilash Village 2nd Steering committee At meeting room, MOWR meeting 27th November, - Discussion of the outline and the results for pilot projects 2008 - Acceptance of Draft Final Report Reporting Session At meeting room, DWIDP 28th November, 2008 - Reporting of the results for the project
Minutes of meeting (M/M) of S/C meeting and participant list of meetings/ seminars are attached in the Volume III DATA AND DROWING 1.
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CHAPTER 2
OVERVIEW OF SLOPE DISASTERS ON NARAYANGHARH –
MUGLING HIGHWAY
2.1 Natural Conditions Related to Slope Disaster in the Study Area
2.1.1 Topography and Geology
Nepal is located in the southern lap of relatively young mountain chain in the Himalayas. The Himalaya is represented by the mountain chain from Indus River in the west to the Bramhaputra River in the east covering total length of about 2400 km.
According to Ganser (1964), the Himalaya is transversely divided into five divisions as Punjab Himalayas, Kumaon Himalayas, Nepal Himalayas, Sikkim and Bhutan Himalayas and North East Frontier and Assam (NEFA) Himalayas.
Out of 2400 km of the Himalayas, Nepal Himalayas occupy the central one-third parts (about 800 km) of the total length extending from Mahakali River in the west to Mechi River in the east. More than 14 peaks exceeding 8000 m including the highest peak of the world, the Mt. Everest belongs to the Nepal Himalayas.
Longitudinally, the Nepal Himalayas have been divided into four, five or six divisions by various authors for their convenience depending on the knowledge they acquire form their study on the subject.
According to Ganser (1964), and Upreti and Le Fort (1999), the Nepal Himalayans can be divided into several geological/topographical zones.
Figure 2.1.1 below shows subdivisions of the Nepal Himalayas considered by Ganser (1964), and Figure 2.1.2 below shows a geological cross section of the Nepal Himalayas presented by Upreti and Le Fort (1999).
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Figure 2.1.1 Subdivision of the Himalaya (modified after Genser 1964)
Figure 2.1.2 Generalized cross section of the Himalaya (modified after Dahal 2005)
As shown in Figure 2.1.1 and Figure 2.1.2 above, the Nepal Himalayas has been divided into several geological zones, and each zone is considered to be bounded by a major thrust fault.
From the north to the south, the South Tibetan Detachment Fault Systems (STDS) bounds the Tibetan Tethys Himalayas and the Higher Himalyas. The Main Central Thrust (MCT) bounds the Higher Himalayas and the Lesser Himalayas. The Main Boundary Thrust (MBT) bounds the Lesser Himalaya and the Siwaliks (the Sub-Himalaya). The Main Frontal Thrust (MFT) bounds the Siwaliks and the Terai plain.
(1) Target Road Section The N-M Highway, a length of 36 km, is located in a mountain range between Narayangharh and Mugling.
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Of the whole section of the N-M Highway, a section of CH1 (Chainage: distance (km) from Narayangharh) 0 to 10 (about 10 km) is located on flat/ very gentle slope of Dun Formation and the Siwalik Zone where as remaining 26 km section (CH 10 to 36) mostly located in a mountainous zone of the Lesser Himalaya.
Therefore slope disasters along the highway have occurred almost along the section of CH 10 to 26. This Study particularly targeted the section of CH 10 to 36 because there are high potential of slope disasters for the highway.
(2) Topography with Chainage The highway is at the left side slope of the valley surrounded by the Trishuli River and at an elevation of approximately 250 m. Relative heights from the highway to the ridges vary with a minimum of about 750 m.
Topographically, the section of CH 10 km to 36 km can be roughly divided into two sections, CH 10 km to 14 km and CH 14 km to 36 km. Section CH 10 km to 14 km is located in the Siwalik Zone mentioned above. Along this section, the Trishuli River runs toward east to south east. Natural slopes along the road face from south to southwest. Within this section, there are three major branches of the Trishuli River, i.e. Das Khola at CH 12+600 m, Khahare Khola at CH 11+300 m, and Jugedhi Khola at CH 10+300 m.
Meanwhile, section CH 14 km to 36 km is located in the Lesser Himalayan Zone. Along this section, the axis of the Trishuli River winds north to south or east to west, and flows to the Siwalik Zone. Based on the Trishuli River meandering, natural disaster/cut slopes along the road generally face north or west. At CH 25+500, the Trishuli River meets the Rigdi Khola, the largest watershed in the Study Area..
Figure 2.1.3 is a map showing slope gradients along the highway. Generally natural slopes along the highway have angles of 30 degrees and more as shown in Figure 2.1.4.
1 Refer to the location map in the opening page or Figure 2.3.1
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Figure 2.1.3 Slope Gradient Map for CH 11 to CH 36
Figure 2.1.4 Slope Aspect Map for CH 11 to CH 36
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(3) Geology with Chainage Bedrock found in the Study area comprises of rocks of the Lesser Himalayan Zone and the Siwalik Zone as mentioned above.
The Lesser Himalayan Zone and the Siwalik Zone are bounded by the MBT. Within the study area, the MBT seems to cross at about CH 14+500 of the highway.
Figure 2.1.5 shows a generalized geological map for the section of CH 10 to 36 of the highway.
Table 2.1.1 shows strata and rocks of each zone.
Table 2.1.1 Strata and Rocks in Study Area Group / Formation Lithology Engineering property dn Dun Formation Molassic sediments Loose, unconsolidated Siwalik Group Molassic sandstone, mudstones, si Soft-medium hard rocks (Neogene) conglomerates Nawakot Complex Upper Nawakot Group (Upper Paleozoic) Dark blue-gray argillaceous slates and Medium-hard rock bg Benighat Slates phylliets, black carbonaceous slates Well-foliated Lower Nawakot Group (Upper Precambrian – Lower Paleozoic) Hard rock, massive, often Dhading Light blue-grey dolomite, dense stromatolitic; dh forming steep cliffs and Dolomite alga, echinoderms (Lower Paleozoic) the Karst Nourpul Phyllites and alternation of phyllite / quartzite np Medium – hard rock Formation and phyllite / dolomite; colour-banding. Purebesi Hard rock, sometime pb Quartzite Strongly ripplemarked orthoquartzite massive, forming steep Memebr cliffs Dandagaon Dark green grey phyllites, some calc phyllites, Medium – hard rock, well da Phyllites rare thin limestones and quartzite foliated White orhtoquartzite, ripplemarked, with Hard rock, forming steep fg Fagfog Quartzite phyllite interzones. cliffs, often massive Phyllites, phyllitic quartzites, greywackes, Kuncha kn conglomerates, rare basic (amphibolitic) Medium – hard rock Formation layers. “Group/ Formation” by Photo-geological Map of Part of Central Nepal (1982)
Along the southern section of CH 10 to 14, road slope geology comprises of sedimentary rocks of the Siwalik Group, and the quaternary terrace/talus deposits. Rocks of the Siwalik Group are distributed in the NE-SW direction, dipping towards northwest, and showing monocline structure.
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aaagahMgigHgwy MainReport r Narayangharh-Mugling Highway
2-6
(Modified after Stöcklin and Bhattarai, 1980 and 1982)
Figure 2.1.5 Generalized Geological Map for CH 11 – CH 36
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Quaternary terrace and talus deposits are distributed on hilly land formed of the Siwalik Group, in and around Phwatar, Syauli, Tandran, Divitar.
Along a northern section of CH 14 – 36, road slope geology comprises of the Lesser Himalayan meta-sedimentary rocks of the Precambrian – Upper Paleozoic. Those Lesser Himalayan rocks are a part of the Nawakot Complex.
The rocks of the Nawakot Complex expose along road cut-slopes between CH 16 – 36 and as well as riverbeds. The Nawakot Complex is covered by the Quaternary terrace deposits and talus deposits along a section of CH 14 – 16. The bedrocks expose on the upper half of mountain slopes along this 2 km section.
Strata of the Nawakot Complex is generally distributed in a direction of E-W and dipping north with angles of 45 – 75 degrees along a section of CH 14 – 27.
Nearby CH 27, strata of the Nawakot Complex dip toward north with low angles. Around CH 28+500 m, strata of the complex show horizontal bedding planes. Form CH 28+500 m to CH 36, the Nawakot Complex dips toward south with moderate – high angles of 50 – 80 degrees.
Therefore a syncline is assumed through the Nawakot Complex. Its synclinal axis is also assumed in a direction of E-W (See Figure 2.1.6).
1.01.0 - - 2.5％2.5 %
2.52.5 ? - 5.05.0 % %
5.05.0 - - 7.57.5 % %
7.57.5 ? - 15.015.0 % %
Assumed synclinal axis of Nawakot Complex
(Schmidt net; lower hemisphere projection)
Figure 2.1.6 Contour Map of bedding planes of the Nawakot Complex
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At around CH 20, the complex is covered by the Quaternary terrace deposits.
The Nawakot Complex is basically classified into the Lower Nawakot Group and the Upper Nawakoto Group. Of the two groups, the following strata and rocks are distributed within the section of CH 10 – 36.
Table 2.1.2 General Geology of Road Slopes (CH 10 – CH 36) Chainage Length Geology CH 10 – 14 4.00 km Siwalik Group, Terrace deposits CH 14 – 16 2.00 km Quaternary unconsolidated sediments, Nourpul Formation CH 16 – 16+400 m 0.40 km Dhading Dolomites CH 16+400 m – 16+700 m 0.30 km Benighat Slate CH 16+700 m – 16+800 m 0.10 km Purebesi Quartzite Member CH 16+800 m – 18+600 m 1.80 km Nourpul Formation CH 18+600 m – 20+300 m 1.70 km Quaternary terrace deposits, Nourpul Formation CH 20+300 m – 33+100 m 12.8 km Nourpul Formation CH 33+100 m – 34+350 m 1.25 km Purebesi Quartzite Member CH 34+350 m – 34+500 m 0.15 km Dandagaon Phyllites CH 34+500 m – 35+900 m 1.40 km Kuncha Formation CH 35+900 m – 36 0.10 km Quaternary terrace deposits
2.1.2 Climate
(1) Climates in Nepal Climate is the collected weather patterns of an area. The climate of Nepal differs drastically in different places and seasons, it has cosmopolitan climates. In general, Nepal has cold and dry winter, hot and dry summer, and heavy monsoon periods. Globally most of the regions have four seasons, however, Nepal has six, they are: Spring or Vasant (Mid-March to Mid-May), Summer or Grishma (Mid-May to Mid-July), Monsoon or Varsa (Mid-July to Mid-September), Autumn or Sharad (Mid-September to Mid-November), Hemant (Mid-November to Mid- January) and Shishir (Mid-January to Mid-March). Further, Nepal has mainly five types of climates which are determined based on altitude ranges (Figure 2.1.7). The climates found in Nepal are as mentioned below:
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(Modified by materials in Home Page in Department of Hydrology and Meteorology)
Figure 2.1.7 Climatic Types in Nepal
Tundra Climate: This climate is found in the Himalayan region which falls above 5000 m from the mean sea level (MSL). The temperature in winter is quite less than the freezing point, while in summer it is slightly less than the freezing point. No vegetation is found in this climate.
Alpine Climate: This climate is prevailed in higher hilly region which falls in the range of 3300-5000 m from the MSL. The temperature in winter is less than the freezing point but in summer it ranges from 5-15 oC. Alpine forests are found in this climate.
Cool Temperate Climate: This climate is found in central hilly region between 2100-3300 m from the MSL. In winter, temperature is less than freezing point while in summer it ranges from 15-20 oC. Coniferous forests are found in this climate.
Warm Temperate Climate: This climate is found in lower hilly region and in the valley which ranges from 900-2100 m from MSL. In winter, temperature ranges from 0-18 oC while in summer it ranges from 17-30 oC. Deciduous forests are found in this climate.
Sub-Tropical Climate: This climate is found in the Mahabharat hills and Terai which ranges below 900 m from the MSL. The temperature in winter ranges from 6-25 oC, while in summer it is 25-40 oC. Evergreen forests are found in this climate.
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(2) Annual Rainfall Distribution in Nepal Rainfall in Nepal is primarily affected by the summer monsoon developed over the Bay of Bengal. Therefore, high rainfall, about 80% of total annual rainfall, receives during the summer monsoon period between June and September. The remaining period receives about 20% of total annual rainfall. In Nepal, rainfall has wide temporal and spatial variability. Several pocket areas in Nepal receive high rainfall more than 3000 mm in a year. Such high annual rainfall receiving areas lies close to Num in eastern Nepal, Gumthang in Central Nepal and Pokhara in western Nepal. The highest rainfall receiving area is Pokhara with more than 4000 mm rainfall in a year.
The topographic effect as well as windward and leeward effect in rainfall is quite significant in Nepal. This is illustrated by the annual rainfalls observed in Pokhara and Mustang areas. Pokhara area lies in windward side. So it has annual rainfall more than 3000 mm whereas Mustang area lies in leeward side which receives annual rainfall less than 250 mm.
(Modified by materials in Home Page in Department of Hydrology and Meteorology)
Figure 2.1.8 Annual Rainfall in Nepal
(3) Climate in Narayangharh-Mugling Highway Elevation of the adjoining areas along the highway ranges from 200-900 m from the MSL, therefore, sub-tropical climate prevails within the vicinity of the highway. In winter, temperature ranges from 6-25oC in the surrounding areas of the highway. Meanwhile, in summer, temperature at the southernmost and depressed part of the highway (i.e Narayangharh
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and surrounding areas) rises considerably high while at the areas lying on elevated places on the northernmost part of the highway are with fair climate. Moreover in summer, temperature ranges from 25-40 oC in the surrounding areas of the highway. Green forests prevail throughout the highway. For reference purposes, the monthly maximum temperature and daily rainfall recorded at Bharatpur station during 2002-06 were analyzed. A highest maximum temperature of 41.2oC was recorded in May, 2004. It was found that April, May and June are the hottest months with average maximum temperature of 37.8 oC, 39.3 oC and 38.6 oC, respectively. The mean annual rainfall in the area is about 2650 mm.
Max. Temperature at Bharatpur (Records used: 2002-2006) 45.0 40.0 35.0 C) o 30.0 25.0 20.0 15.0 Mean of Max. Temp
Temperature ( Temperature 10.0 Highest Max. Temp 5.0 0.0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Figure 2.1.9 Maximum Air Temperature of Bharatpur Station
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2.2 Social and Natural Condition
The social conditions in each VDCs are studied to formulate practical approaches for the slope disasters management.
2.2.1 Outline of the Study Area
(1) Location of the Study Area The Study area is composed of the Kabilash, Darechok, Dahakhani and Chandi Bhanjyang VDCs and Bharatpur Municipality in Chitwan district. Most areas along the Nayarangharh-Mugling Highway which are prone to disaster, include Kabilash VDC that stretches between the sections CH 10 km to 26 km of the highway. Thus studies on social conditions are mainly concentrated in the Kabilash VDC. Its location is highlighted in the map.
Figure 2.2.1 Location of Study Area
(a) Kabilash VDC The Kabilash VDC is one of the major landslides and debris flow disasters prone village along the N-M Highway. The total area of Kabilash VDC is approximately 62 km2. The Kabilash VDC is bounded by the Trishuli river in the north and west; Bharatpur Municipality and Jutpani VDC in the south; and Dahakhani VDC in the east.
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(b) Dahakhani VDC The total area of Darechok VDC is about 39 km2. The boundary of the VDC is Kabilash VDC in the west.
(c) Chandi Bhanjyang VDC The total area of Chandi Bhanjyang VDC is about 48 km2. The VDC is bounded by Dahakhani and Shaktikhor VDCs in the south.
(d) Darechok VDC The total area of Darechok VDC is about 39 km2. The boundary of the VDC is Trishushuli River in the west; Chandi Chandibanjyang VDCs in the south; Saktikhor and Gorka District in the north.
(2) Population According to the Central Bureau of Statistics (CBS) of 2003, the total number of households in the Kabilash, Darechok, Dahakhani and Chandi Bhanjyang VDCs were 985, 1648, 589 and 813, respectively as shown in Table 2.2.1.
Table 2.2.1 Household and Population in the Study Area VDC Household Population Male Female Total Kabilash 985 2767 2748 5513 Dahakhani 589 1807 1764 3571 Chandi Bhanjyang 813 2279 2274 4553 Darechok 1648 4790 4319 9109 Total 4035 11641 11105 22746 Source: CBS2003 (3) Economic Condition (a) Sources of Income In the study area, only 24 % of total households have been engaged in some sorts of economic activities where as 76 % of households are depended on traditional agriculture farming for their livelihood in the study area as shown in Table 2.2.2.
Table2.2.2 Economic Activities in the Study Area VDC Household Nos. Type of Economic Activity Total Having Not having Manuf Trade Trans Servic Other Total Economic Economic acture Activity Activity port Kabilash 985 326 659 11 89 2 3 221 326 Dahakhani 589 17 572 1 6 0 8 2 17 Chandi 813 83 730 o 53 0 20 10 83 Bhanjyang Darechok 1648 549 1099 11 339 14 111 74 549 Total 4035 975 3060 23 487 16 142 307 975 Source: CBS2003
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Rain-fed agriculture is being practiced in the Study area due to lack of irrigation facilities. Similarly, method of raising livestock is conventional using available local breeds which seem less productive. Therefore, income generated from the agricultural production and raising livestock is not enough to maintain the livelihood. Hence, it is common for the youths in the area to leave their village and seek opportunities either to other domestic cities or overseas, working as unskilled labors in order to support the families.
(b) Income Due to steep geographical condition, the cultivated area is very limited. Therefore, income from agricultural sources is insignificant and is difficult to sustain for a period of six months. The estimated average annual incomes of households in four VDCs is shown in Table 2.2.3
Table 2.2.3 Estimated Annual Income per Households in Study Areas Estimated Average Annual Income VDC Total Households (NRs) Kabilash 985 18000 Dahakhani 589 12000 Chandi Bhanjyang 813 15000 Darechok 1648 25000 Total 4035 (average) 17500 Source: CBS2003
(4) Agriculture Condition (a) Cultivated Land and Irrigation Status Total cultivated land of the Study areas is estimated as 1326 hectare with only 108.8 hectares (8.2 percent) under irrigation. Table 2.2.4 shows the estimated cultivated land and irrigation status in four VDCs.
Table 2.2.4 Estimated Cultivated Land and Irrigation Status in Study Areas VDC Estimated Irrigated Irrigation Percent of Irrigation Available Cultivated Area (ha) Method Irrigation Wards Land (ha) Available Kabilash 68.0 61.2 Small Irrigation 90 1, 2, 4, 5, 6 and 7 (2, 4, 5 and 6 are affected from water disaster) Dahakhani 510.0 6.8 Small Irrigation 2 7,3 and 9 Chandi 278.8 27.2 Small Irrigation10 3 Bhanjyang Darechok 476.0 13.6 Pipe 3 9 and 2 Total 1326.0 108.8 8.2 Source: Field Survey, September, 2007
(b) Cropping Pattern and Yield Rates The yearly cropping pattern of the study areas is presented in Table 2.2.5.
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Table 2.2.5 Cropping Pattern in the Study Area Crops Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Monsoon Paddy Spring Paddy Monsoon Maize Spring Maize Wheat Mustard Pulses Vegetables Source: Field Survey, September, 2007 The following Table 2.2.6 shows the cropped areas and their productivity in four VDCs.
Table 2.2.6 Estimated Cropped Areas and Yield Rates
Crops Kabilash Dahakhani Chandi Bhanjyang Darechok Area Yield No.of Area Yield No.of Area Yield No.of Area Yield No.of (ha) Rate House (ha) Rate House (ha) Rate House (ha) Rate House (mt/ha) (mt/ha) (mt/ha) (mt/ha) Paddy 61.2 2.0 325 6.8 0.9 200 54.4 1.5 60 13.6 1.0 85 Wheat 68.0 1.0 380 2.7 0.6 250 23.8 0.6 125 - - - Maize 204.0 1.0 680 510.0 1.0 540 200.0 1.0 650 476.0 0.5 120 Millet 15.7 0.5 620 346.8 0.5 550 102.0 0.4 700 272.0 0.3 950 Pulses 15.7 0.5 870 34.0 0.2 500 12.6 0.3 90 13.6 0.2 800 Vegetable 12.0 200 25.0 150 5.0 50 10.0 300 Source: Field Survey, September, 2007
(5) Drinking Water Situation About 83.0 percent of the households obtain drinking water from pipes linked to water sources. The remaning 17 .0 percent obtain water directly from other sources such as wells, river etc. Table 2.2.7 shows status of households using pipe water and other sources.
Table 2.2.7 Drinking Water Situation VDC % Households Using % Households Using Estimated Time of walking Pipe Water Others Sources (Wells, Distance River etc) (Minutes) Kabilash 70 30 20 Dahakhani 97 3 10 Chandi Bhanjyang 90 10 30 Darechok 75 25 10 Total 83 17 17 Source: Field Survey- September, 2007
(6) Education (a) Literacy Status In the study area, only 46.6 % of the population can read and write. Moreover, male has higher literacy rate of 59 % while female with 41 %.
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Table 2.2.8 Literacy Status in the Study Area
Population of School Age Can't Read and Write Can Read Only Can Read and Write S. N. VDC Male Female Total Male Female Total Male Female Total Male Female Total 1 Kabilas 2342 2364 4706 861 1290 2151 308 301 609 1164 764 1928 2 Dahakhani 1500 1396 2896 638 885 1523 230 186 416 614 310 924 3 Darechok 4125 3708 7833 1056 1455 2511 102 104 206 2944 2148 5092 4 Chandi Bhanjyang 1859 1989 3848 1217 1474 2691 47 49 96 585 455 1040 Total 9826 9457 19283 3772 5104 8876 687 640 1327 5307 3677 8984 Source: CBS 2003 (b) Educational and other Service Institutions Available in Study Areas Education and service institutions are important for uplifting the socio-economic conditions. These are also essential in rendering institutional services during planning and implementation of development programs in above study areas. Table 2.2.9 shows about educational and service institutions in 4 VDCs.
Table 2.2.9 Educational and other Service Institutions Available in Study Areas VDC Schools Health Posts Animal Health NGOs/ Private Services Posts Institutions Kabilash 12 1 - NGOs (Practical Action, Red Cross) Dahakhani 8 1 - - Chandi Bhanjyang 13 2 - - Darechok 15 2 1 1Finance Institution Total 48 6 1 3 Source: VDC Profiles and Field Survey- September, 2007
(7) Environmental Condition Environmental condition in adjoining villages along the N-M Highway has degraded. Natural disasters like landslides, floods and debris flows occur frequently during rainy seasons. Fragile geology is the main reason that affect environmental situation in the Study area. The social and economic conditions of the people in the areas are also affecting the environmental degradation and induce water disasters. Poverty is realized as the primary cause while lack of awareness and education are secondary factors in affecting the current environmental condition. Similarly, deforestation and excessive grazing are the main reasons that cause slope disasters.
(a) Deforestation People are clearing forests for cultivation to produce more to meet their family’s yearly food requirements, and are cutting trees intensively for fuel wood. Therefore, deforestation is one of the key factors for slope disasters.
(b) Haphazard and Over Grazing Cattle, sheep and goats are found almost in each household. People let their cattle, sheep and goats graze haphazardly and freely without any control regardless of carrying capacity of the forests. As a result, forest area has been reducing and damaging day by day. This is also one of the major reasons of natural disasters made by human activities.
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(c) Migration and Land Encroachment People migrating from neighboring districts in Kabilash VDC is in increasing trend. Among them, majority are settling illegally along the road sides of N-M Highway and upper hill areas. Migrants are clearing the forests to settle their houses and cultivating slope lands which are government lands. Due to this, the risk of slope disasters has increased in study areas. Therefore, to reduce the risk of slope disasters the local government should have policy to check the settlements in slope and forest areas. Further, the local government should formulate effective policy to shift the settlements from risky areas which is very challenging.
(8) Heritage and Monuments to be protected in Study Areas There are few monuments and heritage in study areas. These are as follows:
Table 2.2.10 Heritage and Monuments to be Protected in Study Areas
VDC Types Location Number
Kabilash 1. Gadhi Buddhist Ward No -7 1 2. Japanese Remberance Ward No- 1 1 Dahakhani 1. Temple Ward No -5 1 2. Gadhi Chandi Bhanjyang 1. Gadhi Tundikhel 1 2. Temple Ichha Kamana Mandir 1 Darechok 1. Temple Wards-3,9,4 4 2. Gumba Total 9
Source: Field Survey- September, 2007
2.2.2 Social Condition of Kabilash Village
(1) Administrative Structure of Village Kabilash VDC represented by a Chairman, a Vice- Chairman, and nine Ward Chair Persons (one from each ward) and 36 Ward Members (four from each ward). The VDC is entrusted with powers, functions and responsibilities within the village development area:
(a) Relating to planning, administration and finance (b) Relating to development (c) Miscellaneous Currently, there is absence of elected VDC Chairperson. Therefore, VDC Secretary who is an employee of Ministry of Local Government is responsible to carry out the administrative and development works. Political and administrative Charts of Kabilash VDC are presented as given below in the Figure 2.2.2 and 2.2.3.
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Secretary of VDC
Assist. Secretary
Decentralized Decentralized Sub-Health Sub-Center Local Govt. Action Post Support Child &Women Figure 2.2.2 Administrative Chart of Kabilash VDC
Chair Person
Vice Chair Person
Ward 1 Ward 2 Ward 3 Ward 4 Ward 5 Ward 6 Ward 7 Ward 8 Ward 9 Chair Chair Chair Chair Chair Chair Chair Chair Chair Person Person Person Person Person Person Person Person Person
Ward 1 Ward 2 Ward 3 Ward 4 Ward 5 Ward 6 Ward 7 Ward 8 Ward 9 Member Member Member Member Member Member Member Member Member 4 4 4 4 4 4 4 4 4
Figure 2.2.3 Political Organization of Kabilash VDC
The development projects completed by Kabilash VDC in 2006/2007 include construction of primary school buildings, procurement of electric posts, provision of trail roads, drinking water and small scale irrigation system. These projects were implemented under the financial assistance of District Development Committee of Chitwan. The total estimated budget of VDC in 2007/2008 is Rs 2,265,000.
(2) Land Use The land-use pattern in Kabilash is presented in the following figure. Most of the land areas are covered with forests.
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Figure 2.2.4 Land-use Map of Kabilash VDC
(3) Disaster Prone Areas in the Kabilash Village Disasters prone areas in Kabilash are in wards 1, 6, 8 and 9 (Figure 2.2.5). In 2003 and 2006, disasters occurred in these wards, with many lives and properties lost due to landslides and debris flows. Therefore, much attention should be paid on these areas concerning disasters risk management.
Figure 2.2.5 Disasters Risk Areas of Kabilash Village
(4) Organizations Involved in Disaster Management in Kabilash Village Disasters management programs from various organizations are being launched in the Kabilash VDC through local community group or through school students. Some of the organizations involved in the disasters management and their on-going programs in the
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Kabilash VDC are briefly discussed.
(a) Forests Committees In the past, 6 forests committees were formed in the VDC to conserve and manage the forests. Among them only 3 forests committees are active at present. The forests committees have been requesting to the Government to handover these forests to local community management. Still no any decision has been taken in this connection.
(b) Climate Change Impact Disaster Management Group and Practical Action (INGO) Some energetic youths of the VDC have formed the group in the VDC. The group had made some studies on the causes of deforestation in the VDC and concluded that poverty is the main cause of deforestation as they found, people have been cutting timbers to earn money by selling them in local markets and to use them as fuel by themselves. Therefore, the group is launching some income generation programs including goats keeping in the VDC since 2004 to raise the income level of the people to support on the conservation of the forests. The group is also making some check dams in the streams in the VDC with people participation.
(c) Red Cross Red Cross organized Disaster Risk Reduction Training to Kabilash High School students of classes above grade six. The training was organized to teach some preventive and safeguard measures from the landslides, debris flows and earthquake disasters to the students.
(d) Mugling Narayangharh Water Induced Disaster Prevention Project (MNWIDPP): The MNWIDPP has been carrying out major landslides and debris flows prevention works in the catchments of the cross streams along the M-N Highway. The project has emphasized on non-structural and structural measures for slope disasters prevention. Similarly, the project has been focusing on immediate and long-term countermeasure works for slope stabilization.
2.2.3 Disaster Management in National Level
The detail on this content is described in “Volume III DATA AND DRAWING”. The outline on the content is mentioned in this section.
(1) Institutional Arrangements for Natural Disaster Relief In general, Nepal is highly prone to various types of disasters with major ones induced by water. Each year after occurrence of disasters, approximately a thousand people are killed, about one
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The Study on Disaster Risk Management for Narayangharh-Mugling Highway Main Report hundred were lost and thousands of families are demoralized. In addition, properties worth millions are ruined. To cope with such natural calamity, a disaster management system has been formulated in the national level.
The Natural Disaster Relief Act (NDRA) has been established to constitute the organizational structure through which the various activities of disaster management are being carried out effectively and efficiently.
(2) National Action Plan on Disaster Management The major programs on disaster preparedness, response, reconstruction, and mitigation action plan have been formulated in 2001 as follows.
1) Measures related Geological, Hydrological and Metrological Hazard Assessment Executing organization: MOFSC, TU, DWIDP, and DMG 2) Awareness Raising Programs Executing organization: MOIC and MOHA 3) Training/Rehearsals/Simulations Executing organization: NRCS, MOHA, Local NGOs 4) Disaster Management Information System Executing organization: MOIC, NA, Police, INGOs, NGOs 5) National Land Use and Cover Plan Executing organization: MOFSC, MOWR 6) Policy on Disaster Reduction Measures Executing organization: MOFSC, MOWR 7) Promotion of Regional and Sub-regional Cooperation between Countries exposed to same Natural Hazards Executing organization: MOFA, MOWR, and MOI 8) Establishment of Documentation Centre on Disaster Management Executing organization: MOFA, MOWR, and MOI
(3) Activity of DWIDP on Sediment- Related Disaster Water Induced Disaster Prevention Technical Centre (DPTC) was established in 1991. Eventually, it became the DWIDP in February 2000 under the Ministry of Water Resources as the lead agency. The Government of Japan through JICA has been assisting to promote the capacity of Government of Nepal and the communities to cope with water induced disasters.
The Disaster Mitigation Support Program Project (DMSP) through JICA cooperation was an attempt to manage these water induced disasters in a comprehensive manner with community involvement through model mitigation works.
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The three major activities in DWIDP that contribute to mitigation and reduction of water induced disaster in Nepal. (Source: DWIDP, an Introduction)
(a) Technology Development Work (b) Training, Study and Introduction Work (c) Water Induced Disaster Mitigation Work Activities mentioned in the former clause are carried out by human resources of total 231 which are shown in the Table 2.2.11. (Source: DWIDP, an Introduction)
Table 2.2.11 Manpower of DWIDP
Unit GI GII GIII NG I NGII NC Total Department 3 7 24 29 2 5 70 Division - 7 22 58 9 30 126 Subdivision - - 5 10 10 10 35 3 14 51 148 21 45 231 G: Gazetted, NG: Non-Gazetted, NC: Non-classified (4) Activities for Road Maintenance Work of Work of Division Road Office (DRO), Bharatpur, Chitwan (a) Organization of Division Office Bharatpur, Chitwan DRO, Bharatpur is responsible for disaster management and maintenance of strategic roads in Chitwan and Dhading districts of Nepal. These roads comprise 186 km national highways and 23 km feeder roads. In addition to this, the office is also involved in construction of major bridges in said two districts.
DOR is responsible to carry out on and off -road works within 25m from the Highway. However, DOR and DWIDP are carrying out their preventive and maintenance works in close collaboration. (Source: Road Division Office, Bharatpur, 2007)
N-M Highway lies under the supervision and maintenance of Division Road Office in Bharatpur, Chitwan district. Under the Technical Section, Division Office, Bharatpur, 4 Engineers, 12 sub Engineers, 5 Driver Operators, 1 Lab Technician and 2 Lab boys have been employed on permanent basis. In addition, 11 Supervisors and 75 Length workers have been deployed on temporary basis. In case of urgent disaster, equipment from other offices such as Hetauda, Janakpur, Naubishe and Gajuri have been used in disaster sites within N-M Highway.
(b) Routine Maintenance Total 75 length workers are employed in Chitwan district and each worker is assigned a section of road and is responsible for the routine maintenance. At the beginning of fiscal year, agreement of each length worker is updated for the period of one year. A site of mechanical
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office with 3 loader machines is responsible for routine maintenance of N-M Highway. However, considering the nature of urgency, the required number of operators and machines are deployed in site from other Civil Division Offices situated in Hetauda, Janakpur and Bharatpur.
(c) Response on Urgent Disaster and Reopening As mentioned in above (b) in order to response on urgent disaster and reopening considering the nature of urgency, the required number of operators and machines are deployed in disaster sites from the Division offices Hetauda, Janakpur and Bharatpur. Currently, the road maintenance sites are located in Mugling, Naubise and Gajuri. Currently, in Technical Section of the Road Division office, Bharatpur, 4 Engineers, 12 Sub-engineers, 5 Driver Operators, 1 Lab Technicians and 2 Lab boys are working on permanent basis. In addition, 11 Supervisors and 75 Length workers are working as temporary. The manpower is responsible to look after Chitwan and Dhading districts.
(d) Road Maintenance Expenditure at the Project Office Level Budget allocation for N-M Highway for Fiscal Year 2006/2007 is as follows:
Table 2.2.12 Road Maintenance Expenditure for N-M Highway for Fiscal Year 2006/2007 Routine Maintenance NRs 606,513.00 Recurrent Maintenance NRs 460,206.24 Recurrent Major NRs 1027,564.80 Khahare Bridge Maintenance (Retaining/other NRs 360,877.00 structure/plumb concrete works) Source: DOR
2.2.4 Rainfall Feature in the Study Area
The detail on this content is described in “Volume III DATA AND DRAWING”. The outline on the content is mentioned in this section.
(1) Spatial Distribution The spatial distribution of rainfall stations in and around study area is prepared (Figure 2.2.6). There is one station at Khahare Khola and other nearby stations from the highway is Devghat and Bharatpur. All these 3 stations lie on the southern part of the highway.
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Figure 2.2.6 Rainfall stations in and around the study area.
(2) Operational Conditions and Data Availability The stations in the study area are illustrated briefly.
Khahare Khola Station: This station was established after 2003 disaster by the Divisional Road Office, Bharatpur at 11 km on N-M Highway. Non-recording rain gauge was installed and daily rainfalls are being measured since 2004. Present operational condition of the station seems satisfactory.
Devghat Station: This station is located at downstream of confluence of Kali Gandaki. At this station, both non-recording and recording types of rain gauges are installed by the Department of Hydrology and Meteorology (DHM). The hourly and daily rainfalls are being recorded at this station since 1998. Operational condition of the station at present is satisfactory. Daily rainfalls data of 1998-2006 of this station were made available.
Bharatpur Station: The station has non-recording rain gauge and is located in Bharatpur Municipality compound. This station is managed by Department of Hydrology and Meteorology (DHM). Discontinuous daily rainfall records of 2002-06 were made available; however, operational condition of the station seems satisfactory.
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(3) Analysis of 2003 Disaster Rainfall The rainfall distribution pattern of 31 July 2003 was studied. The rainfall chart of recording rain gauge of Devghat station showed rain started at 8:45 AM of 30 July and continued until 5:00 AM of 31 July, and the total rainfall amount was 446.2 mm in 20.25 hours (Figure 2.2.7). It showed about 25% of total rainfall (i.e. 114.5 mm) had occurred in the first 10 hours (between 8:45 AM and 18:45 PM), about 50% of total rainfall (i.e. 221.5 mm) had occurred in 12.5 hours (between 8:45 AM and 21:15 PM), and about 75% of total rainfall (i.e. 339.5 mm) had occurred in 14 hours (between 8:45 AM and 22:45 PM). It indicates that in 4 hours period (between 18.45 PM and 22.45 PM) 225.5 mm of rainfall occurred, and it devastated the highway with landslides and debris flows.
Rainfall Distribution
500 100
450 Cumulative rainfall 90
400 % of total rainfall 80
350 70
300 60
250 50
200 40 Rainfall (mm)
150 30 rainfall total % of
100 20
50 10
0 0 8.45 9.45 1.45 2.45 3.45 4.45 10.45 11.45 12.45 13.45 14.45 15.45 16.45 17.45 18.45 19.45 20.45 21.45 22.45 23.45 24.45 Rain started time: 8:45 AM Time (hr) Date: 31 July 2003
Figure 2.2.7 Rainfall Distribution on 31 July 2003 at Devghat station
Similarly, rainfall intensity curve of 2003 disastrous rainfall is developed to use as a reference for getting ideas on devastating intensity of rain and thereby develop the warning system for the possibility of the highway disasters (Figure 2.2.8). The relation used for developing rainfall intensity curve is given below.
C I = (1) ()t + a b Where, I = Rainfall intensity (mm/hr) t = Time duration (min) a, b, C = Constants
From the above analysis, it can be concluded that occurrence of very high intensity rain (i.e. more than 80 mm/hr) after almost 12 hours of continuous rainfall with considerable amount can cause devastating debris flow along the streams crossing the highway.
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Rainfall Intensity Curve (Date: 31 July 2003) 100 90 80 70 60 I = 5385.55 / (t + 141)0.759 50 40 30
Intensity (mm/hr) 20 10 0 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.00 11.00 12.00 13.00 14.00 15.00 16.00 17.00 18.00 19.00 20.00 t = time (min) Hours
Figure 2.2.8 Rainfall Intensity Curve for 31 July 2003 (Devghat Station)
(4) Daily Rainfall Patterns during Past Disasters The daily rainfall patterns during 2003, 2006 and 2006 disasters and the pattern of recent heavy rainfall day were analyzed.
Daily Rainfall Pattern (2003) 600
500 446.2 400 364.5
300
200
Rainfall (mm) 71.6 100 39.8 5.9 6.3 11.5 23.8 0 29-Jul 30-Jul 31-Jul 1-Aug 29-Jul 30-Jul 31-Jul 1-Aug Devghat Bharatpur
Daily Rainfall Pattern (2006) 500
376.4 400 346.0 289.6 300 256.0 236.0 200
Rainfall (mm) 99.0 100 0.0 0.0 0.0 0 8-Sep 9-Sep 10-Sep 8-Sep 9-Sep 10-Sep 8-Sep 9-Sep 10-Sep Devghat Bharatpur Khahare Khola
Daily Rainfall Pattern (2007) 400
298 300 229.4 197.4 200
94 Rainfall (mm) 100 58.7 38.1
0 16-Aug 17-Aug 16-Aug 17-Aug 16-Aug 17-Aug Devghat Bharatpur Khahare Khola
Figure 2.2.9 Daily Rainfall Pattern during 2006 Disaster
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With analyzing daily rainfall pattern of Devghat stations during 2003 and 2006 disaster, it can be concluded that landslides and debris flow occur on the highway if rainfall continued for 2 days with considerable amount of rainfall on the first day and heavy rainfall of more than 300 mm on the second day. From the inspection of the highway during 2007, it can be concluded that highway is vulnerable to landslides when rainfall continues for 2 days with considerable amount of rainfall on the first day and heavy rainfall of more than 200 mm on the second day.
(5) Threshold Rainfall Amount Determination for Early Warning The accumulated rainfall amounts and intensities have been used for threshold rainfall amount in Japan. However, it is has been pointed out that they do not have enough accuracy for the prediction. In this study, the modified rainfall amounts of 6, 12 and 24-hour half-value, which were estimated using annual maximum daily rainfalls of 1998-2006 during at Devghat station, instead of accumulated rainfall amount for early warning employ for the purpose of increasing the reliability of early warning against the rainfall triggered disasters. The daily rainfall amounts were divided by 24 to convert it to hourly rainfall amounts because H-hour half-value rainfall amounts are estimated based on hourly rainfalls. However, hourly rainfall data on the day of maximum rainfall in 2003 were derived from the rainfall recording chart. The relation used for estimation of T-hour half-value rainfall amounts is as shown in the following equation.
i/H RAHhv(t) = 0.5 x HR(i) Where,
RAHhv(t) = rainfall amount of H-hour half-value of time ‘t’ i = ‘i' hour before from time ‘t’ (hour) H = H-hour half-value: Half-value period of hourly rainfall reduction (hour) H = 6, 12, 24 HR(i) = Hourly rainfall of ‘i +1’ to ‘i' hour before from time ‘t’
The maximum modified rainfall amounts of 6, 12 and 24-hour half-value were computed for the maximum annual daily rainfall days during 1998-2006 at Devghat station. The return periods of 6, 12 and 24-hour half-value rainfall amounts and 24-hour maximum recorded rainfall amounts were analyzed. The return periods of 6, 12 and 24-hour half-value rainfall amounts of 2003 disaster are 85, 58 and 25 years, respectively. Similarly, the return periods of 6, 12 and 24-hour half-value rainfall amounts of 2006 disaster are 4, 5 and 9 years, respectively. The 12-hour half-life rainfall amounts have in-between values of return period for both 2003 and 2006 years among the 6, 12 and 24-hour half-value modified rainfall amounts (Table 2.2.13). As 12-hour half-value modified rainfall has in-between value of return period, it can
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be used effectively for early warning of disasters which occur due to high intensity rainfall as well as gentle and long duration rainfall. Therefore, 12-hour half-value modified rainfall amount is decided to use as threshold value in early warning for traffic control and residents evacuation on the N-M Highway.
Table 2.2.13 Return Periods of Each Type of Rainfall Amounts
MaximumMaximum Rainfall of of ModifiedMaximum Rainfall of 6-hour of ModifiedMaximum Rainfall of of ModifiedMaximum Rainfall of of 24-hour Rainfall half-value Rainfall 12-hour half-value 24-hour half-value Year Date 24-houAmountr 6-hourAmount Half Life 12-hourRainfall Half Amount Life 24-hourRainfall Half Amount Life mm (yr) mm (yr) mm (yr) mm (yr) 1998 5-Jul 162.3 (1) 31 (1) 60.2 (1) 118.8 (1) 1999 25-Aug 250 (3) 47.7 (2) 92.8 (2) 182.9 (3) 2000 24-May 131 (1) 25 (1) 48.6 (1) 95.9 (1) 2001 30-Jul 224.9 (2) 42.9 (2) 83.5 (2) 164.6 (2) 2002 12-Jul 180.2 (2) 34.4 (2) 66.9 (2) 131.9 (2) 2003 31-Jul 446.2 (16) 224 (85) 303 (58) 362 (25) 2004 3-Sep 152.3 (1) 29.1 (1) 56.5 (1) 111.4 (1) 2005 7-Aug 100.3 (1) 19.1 (1) 37.2 (1) 73.4 (1) 2006 9-Sep 376.4 (9) 71.8 (4) 139.7 (5) 275.4 (9) Note: Values in parentheses indicate return periods
The early warning/ evacuation system should be developed for minimizing the loss of properties and lives from rainfall triggered disasters on the highway and villages. Therefore, two separate early warning criteria are proposed for traffic control on the highway and for evacuation of village residents.
Table 2.2.14 Warning Levels by the Modified Rainfall Amounts
Warning Threshold rainfall amount Action Level for the Highway for Residents Evacuation 24-hour half-value modified Warning: Warning: rainfall amount : 180mm Recommendation Recommendation for evacuation Level IV Return periods: 10-year mentioning road is unsafe 24-hour half-value modified Caution: rainfall amount : 140mm Recommendation Level III Return periods: 5-year mentioning careful road passage 24-hour half-value modified Preparation: Caution: Level II rainfall amount : 80mm (DRO)Calling up staff/ Recommendation to prepare for Return periods: 2-year workers/equipment for evacuation 24-hour half-value modified emergency action Preparation: rainfall amount : 60mm Upload to web-page of Informing the committee, Return periods: 1-year DRO and Kabilash monitoring team, Ward Level I VDC the amount of 1 representative in VDC. Upload to hour rainfall web-page of DRO and Kabilash VDC the amount 1 hour rainfall
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In this system using the modified rainfall amounts, the predicted hourly rainfall values are employed. The predicted value means a predicted amount as one hour later at a certain point in time. The result of the analysis for the rainfall of June 31, 2003 is indicated following equation and Figure 2.2.10.The correlation coefficient between the observed value and the predicted value is 0.909.
Rprd = Robs (mm)
Where,
Rprd: Predicted hourly value as one hour later at a certain point in time
Robs: Observed hourly value at a certain point in time
Observed VS Predicted Hourly Rainfall (31 July 2003) 70
60
50 RPr ed/RObs = 1 40
30
20 r2 = 0.909 10 Predicted Hourly Rainfall (mm) Rainfall Hourly Predicted 0 0 10203040506070 Observed Hourly Rainfall (mm)
Figure 2.2.10 Observed hourly rainfall and predicted hourly rainfall on the rainfall of June 31, 2003
The threshold rainfall amounts and the predicted values in this study are preferable to be renewing by new data.
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2.3 Road Slope Disasters on Narayangharh-Mugling Highway in 2003
The N-M Highway was damaged badly due to landslides and debris flows because of heavy rainfall (446.2 mm at Devghat) on 31 July 2003. The damages caused by 2003 disasters in the villages along the highway and on the highway itself were studied.
In this section, the characteristics of the road slope disaster in 2003 is comprehensively described, that based on reference data and photo identification using satellite photos in 2005, aerial photos in 1992 and on-site photos after 2003 disaster. Next, the objective figures of the damages are reviewed.
2.3.1 The characteristics in 2003 disaster
The boundary of the debris movement characteristics in the slope is Station 15 as shown in Figure 2.3.1 below. Characteristics of the road slope disaster in each area are also shown in said figure.
(1) Station 10 to 15 The dip of stratum is opposite to the slope, and the upper portion of the slope is steep where as middle to the lower portion of the slope is relatively gentle and dominated by talus deposits, and the width of the stream is relatively broad. Some failures occur in the upper slope, which induce the collapse of the riverside and debris flow on the stream.
At the moment, there is no serious influence to the road because of substantial distance between the stream level and the road. However, it is possible that consecutive debris flow destroys the road due to rising stream level by the debris deposit in near future.
There is no deep failure (deep slide) in this area.
(2) Station 15 to 36 (to Mugling) The dip of stratum is parallel to the slope, and there are many clear features indicating large scale slide. Many failures were occurred along the streams around the slide features that were not moved themselves in 2003 disaster, especially between Station 17 to 28. It is possible that the failures induce some slide. Few failures like these types were occurred in 2003 between Station 28 to Mugling.
These failures that occurred along the streams between Station 17 to 28 flew over the N-M Highway as debris flows, and did not destroy the highway.
There is no deep failure (deep slide) in this area.
Other types of the debris movement there were occurred all over the highway in 2003 disaster,
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Road foundation failure: the failures were occurred by 1) flowing surface water over the road and 2) erosion along the Trishuli River.
Small slide movement: the slide movements were not accompanied by slide feature, which were occurred in the mountainside slope.
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CH 35km
CH 30km
CH 20km CH 25km
CH 15km
CH 10km
Figure 2.3.1 Hazard map for CH 10 – 36 of N-M Highway
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2.3.2 Damages in 2003 disaster
(1) Damages Caused in the Villages along the Highway The damages caused by 2003 and 2006 disasters in the villages lying along the highway were studied. In 2003 disaster, 18 people died and 69 houses were destroyed in Kabilash Village development committee (VDC). Similarly, in Chandi Bhanjyang VDC 9 people died, 5 injured and 5 houses were damaged (Table 2.3.1). In Darechok VDC, 1 person died and 2 houses were destroyed in 2003 disaster (Figure 2.3.2). However, in 2006 disaster, 3 people died and 15 houses destroyed in Kabilash VDC because of landslides and debris flows.
Table 2.3.1 Lives and Properties Lost in Villages during 2003 & 2006 Disasters People Affected Livestock House Public Estimated Year VDC/District Death Injured Family Loss Destroyed Properties Loss (Nos) (Nos) (Nos) (Nos) (Nos) Losses (NRs) Darechok 1 2 13 2 440,000.00 2003 Chandi Bhanjyang 9 5 4 44 5 Culvert, School-1 530,000.00 Kabilas 18 69 164 69 Road 2,022,000.00 2006 Kabilas 3 15 NA Source: Disaster Review 2003 & 2006, DWIDP & VDC Records
Lives and Properties Lost by 2003 Disaster 80 69 70 Death 60 Houses Destroyed 50 40
Numbers 30 18 20 9 10 5 1 2 0 Darechok Chandi Bhanjyang Kabilas VDCs
Figure 2.3.2 Lives and Properties Lost in 2003 Disaster in Villages
(2) Damages Caused on the Narayangharh-Mugling Highway Damages recorded caused on the N-M Highway are presented in Table 2.3.2. During 2003 disaster on the N-M Highway, 2 bridges, 9 culverts, 8675 m road pavement, 494 m retaining wall and 1480 m embankment were damaged. The bigger volumes of debris flow occurred in Mohore Khola (21+560), gullies of Ch. 23+760, Khahare Khola (11+300) and Gaighat Khola (18+460 ); and total estimated volume of debris at those locations were 60,268, 28,955, 22,837 and 15,089 m3 respectively as shown in Table 2.3.3.
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Table 2.3.2 Properties Lost on N-M Highway by 2003 Disaster S. N. Property Destroyed Units 1 Bridges Destroyed (Nos) 2 2 Culverts Destroyed (Nos) 9 3 Road Pavement Destroyed (m) 8675 4 Retaining Wall Damaged (m) 494 5 Embankment Damaged (m) 1480 Source: DWIDP Bulletin 2005-6
The Central Divisional Road Office (CDRO), Bharatpur played major role for rehabilitation of N-M Highway after 2003 disaster. The CDRO has cleared about 199,529 m3 of debris coming from up hill sides and cross streams. At some location vehicles movement was disturbed up to 28 days because of debris clearance works.
Table 2.3.3 Debris Deposited on N-M Highway in 2003 Disaster and CDRO’s Actions Contractors E/W Machinery Work (hr) Disturbed Volume Total S. N. Chainage 3 3 3 Work Volume (m ) Loader Excavator Days (m ) Volume (m ) 1 8+000 24 1 1560 1560 2 11+300 21075 10.5 9 3 1762 22837 3 16+800 5 325 325 4 17+560 1003 15 3 975 1978 5 18+460 10093 38 21 10 4990 15089 6 20+800 148 20 2 1300 1448 7 21+560 43938 134 63.5 28 16330 60268 8 23+550 707 4 260 967 9 23+760 2932 251.7 80.5 25 26023 28955 10 23+770 23 3.5 5 1915 1915 11 23+800 1715 35 12 2275 3990 12 24+400 1194 16.5 3 11 1432 2626 13 24+740 3671 16.75 8 1089 4760 14 27+060 3663 3663 15 27+850 3522 3522 16 29+500 1596 1596 17 30+890 654 29 15 1885 2539 18 31+400 2232 1.5 1 97.5 2329 19 31+890 3231 3231 20 32+400 6.5 422 422 21 34+090 139 139 Source: DWIDP Bulletin 2005-6
(3) N-M Highway Rehabilitation Works by CDRO after 2003 Disaster Besides debris clearance works to allow for vehicular movement on the N-M Highway after the 2003 disaster, CDRO has also constructed slope stabilization structures along the highway as preventive measures against slope disasters. As presented in Table 2.3.4, the CDOR has constructed breast walls (809 m), retaining walls (538 m), check dams (42), guide walls (104 m), spur (1), anchor walls (4), catch pits (7) and toe walls (269 m).
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Table 2.3.4 CDRO’s Rehabilitation Works after 2003 Disaster S. N. Structure Constructed Unit 1 Breast walls (m) 809 2 Retaining walls (m) 538 3 Check dams (Nos) 42 4 Guide walls (m) 104 5 Anchor walls (Nos) 4 6 Catch pits (Nos) 7 7 Toe walls (m) 269 8 Spur (Nos) 1 Source: DWIDP Bulletin 2005-6
The details on the slope stabilization structures constructed by the Central Divisional Road Office (CDRO) Bharatpur after 2003 disasters are presented with their locations (Table 2.3.5).
Table 2.3.5 CDRO’s Slope Stabilization Works after 2003 Disaster and their Locations S. N. Structure Constructed Location 1 Breast wall a. Gabion 8+930, 12+040, 15+360, 16+990, 17+115, 18+850, 20+350, 26+710, 30+550, 31+475, 31+810 b. Masonry 8+660, 13+035, 18+750, 18+790, 19+580, 20+350, 20+800, 21+130, 21+925, 24+000, 24+600, 26+710, 30+550 2 Retaining wall a. Gabion 9+500, 14+300, 18+696, 20+350, 20+850, 21+080, 21+642, 21+850, 20+800, 27+280 b. Masonry 11+620, 15+060, 17+850, 18+355, 18+415, 21+175, 21+850, 23+423, 23+570, 11+650, 17+050, 24+850, 27+160, 27+280, 28+080, 31+630, 31+810, 32+550, c. R.C.C. 21+040, 29+325 3 Toe Wall a. Concrete toe wall 16+850, 17+850, 19+450, 24+000 b. Masonry toe wall 23+785, 32+475 c. Gabion toe wall 26+250, 32+475 4 Catch pit wall 15+060, 24+750, 25+070, 27+070, 29+825, 30+456, 31+400 5 Check dam a. Gabion 11+100, 15+060, 16+950, 17+295, 17+560, 18+460, 20+200, 20+800, 21+130, 21+560, 22+150, 23+080, 23+550, 23+780, 24+400, 24+750, 25+070, 26+960, 27+070, 27+160, 27+200, 27+545, 27+600, 27+860, 29+825, 30+456, 30+890, 31+400, 32+890, 34+090, b. Masonry 15+930, 30+890 6 Gabion guide wall 11+300, 19+450, 18+460 7 Gabion spur 11+300 8 R. C. C. Anchor wall 17+115, 24+600, 31+875, 31+890 Source: DWIDP Bulletin 2005-6
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2.4 Debris Flow Disaster at Ruwa Khola in 2003
The 2003 heavy rainfall caused a lot of slope failures and associated debris flow in the Ruwa Khola, a branch of the Marsyangdi River, and other river valleys.
The Marsyangdi power house is located on the left side just at the confluence of the Marsyangdi River and its tributary, the Ruwa Khola about 4 km north from Mugling along the way to Pokhara. The Marsyangdi power house started operation and has an installed capacity of 69 MW.
The 2003 rainfall and its triggering debris flow in the Ruwa Khola on July 30 caused a large damage to the power house, stopping operation for nine days with a direct loss of about 1.0 billion Rs.
The following describes the 2003 sediment-related disaster and associated damage. In addition, the previous information is based on JICA Expert Report (Hiruma, Dec., 2003) titled “Debris Flow Disaster in Ruwa Khola in July 2003 and Its Affection to Marsyangdi Power House”.
2.4.1 Outline of Debris Flow Disaster
(1) Occurrence Time and Triggers Date and time of Occurrence: AM 2:00, July 30, 2003.
Trigger: Continuous rainfall from 17:00, July 29 (446.2 mm from 8:45 a,m., July 30 to 5:00 a.m., July 31, at Devghat Station)
(2) Debris Flow Disaster The debris flow occurrence is summarized, on the basis of the field reconnaissance after debris flow disaster, which are as follows:
a) Slope failures on the valley slopes upstream of the power house and associated debris flows produced a large amount of debris materials, which began to be deposited from about 300 m upstream of the power house. That raised riverbed of about 3 to 4 m.
b) Before debris flow disaster, there was a foot trail, which crosses the river just upstream of the mouth of the Ruwa Khola. The path road blocked the river, in turn leading to deposition of debris flow sediment behind the path road, consequently damming up the river and raising the riverbed.
c) With the rising of the riverbed, the debris flow sediment gradually spread out laterally and partially the inlet of cooling water tunnel and the power house.
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d) When the second debris flow occurred, the natural dam by the debris flow sediments was eroded by debris flow and failed, causing a larger debris flow. The bridge foundation and the box culvert were washed out by the associated debris flow
e) The failed sediments associated the debris flow materials flowed down into the Marsyangdi River, plugged the Marsyangdi River and dammed up river water again. This caused the river water and associated debris materials flowed into the tailrace tunnel.
a) Before debris flow b) When the first wave of c) After the second wave of debris flow occurrence debris flow occurrence
Figure 2.4.1 Conceptual Illustration of the 2003 Debris Flow Occurrence
2.4.2 Associated Damages
(1) Power plant a) The power plant building was buried under debris flow sediments. The building itself was not damaged, the debris flow and subsequent inundation stood at 30 cm in the first floor and at 1.2 m in the basement. Draining and cleaning took three days.
b) The building foundation was exposed due to debris flow. Emergency measures, using gabion walls were executed.
c) Debris flow from the Ruwa Khola blocked the Marsyangdi River. The river water and associated debris materials flowed into the tailrace tunnel which faces the Marsyangdi River. One of the three gates was deformed by hit of shoulders. Drainage and cleaning
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took about one month.
(2) Other facilities a) Outlet of cooling water tunnel facing the Ruwa Khola was buried under debris flow deposits.
b) Water supply pipe was washed out by debris flow.
c) Te box culvert just upstream of the confluence of the Marsyangdi River and the Ruwa Khola was completely washed out by the associated debris flow
d) The bridge foundation was partially washed out by the associated debris flow.
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