UPGRADED FEASIBILITY STUDY REPORT Volume I: Main Report Prepared By: C S E P T N A A D T CONSUL Mahalaxmisthan, Lalitpur 977 1 5527469, email: [email protected] June 2015 Upgraded Feasibility Study Report Suri Khola Hydropower Project Table of content Salient Features of the Project ........................................................................... X 1 INTRODUCTION ........................................................................................ 1 1.1 GENERAL .................................................................................................. 1 1.2 OBJECTIVE OF THE STUDY ..................................................................... 2 1.3 SCOPE OF WORK ..................................................................................... 2 1.4 STUDY METHODOLOGY ........................................................................... 3 1.5 ORGANIZATION OF THE REPORT ............................................................ 3 2 DESCRIPTION OF PROJECT AREA .......................................................... 5 2.1 LOCATION ................................................................................................. 5 2.2 PHYSICAL FEATURES .............................................................................. 5 2.3 ACCESSIBILITY ......................................................................................... 6 2.4 INFRASTRUCTURE FACILITIES ................................................................ 7 3 FIELD INVESTIGATION AND DATA COLLECTION ................................... 8 3.1 TOPOGRAPHICAL SURVEY AND MAPPING ............................................. 8 3.1.1 Objectives and scope of works .................................................................... 8 3.1.2 Available Maps ........................................................................................... 8 3.1.3 Surveying ................................................................................................... 9 3.1.4 Mapping ................................................................................................... 12 3.2 HYDROLOGICAL INVESTIGATIONS ........................................................ 12 3.2.1 Collection of Available Meteorological and Hydrological Data ..................... 12 3.3 GEOLOGICAL AND GEOTECHNICAL INVESTIGATIONS......................... 15 3.3.1 Collection of Available Data and Map ........................................................ 15 3.3.2 Geotechnical Investigations....................................................................... 15 3.4 CONSTRUCTION MATERIAL SURVEY AND TESTING ............................ 15 3.5 TRANSMISSION LINE ROUTE SURVEY .................................................. 16 3.6 FINDINGS & REMARKS ........................................................................... 16 4 HYDROLOGICAL STUDIES ..................................................................... 17 4.1 GENERAL ................................................................................................ 17 4.2 HYDRO-METEOROLOGICAL CHARACTERISTICS OF NEPAL ................ 17 4.3 BASIN PHYSIOGRAPHY AND DRAINAGE ............................................... 18 4.4 CLIMATOLOGICAL DATA ........................................................................ 18 4.4.1 Long Term Mean Monthly and Annual Rainfall ........................................... 18 4.4.2 Temperature ............................................................................................. 19 4.5 HYDROLOGICAL DATA COLLECTION..................................................... 19 4.5.1 Measured Flow Data ................................................................................. 19 4.5.2 Long Term Flow Series ............................................................................. 20 4.6 LONG TERM FLOW ANALYSIS ................................................................ 20 4.6.1 Regional Regression Method .................................................................... 21 4.6.2 Similar Catchment Area Method ................................................................ 26 4.6.3 MIP Method .............................................................................................. 27 4.6.4 WECS/DHM Method ................................................................................. 28 4.6.5 Actually Gauged and Measured Data ........................................................ 29 4.6.6 Summary, Comparison and Adoption of Mean Monthly Flow ...................... 29 4.6.7 Adopted Mean Monthly Flow for Suri Intake ............................................... 30 4.7 FLOW DURATION CURVE ....................................................................... 31 4.8 RIPARIAN RELEASE ............................................................................... 32 4.9 DESIGN FLOODS .................................................................................... 32 4.9.1 Correlation method (flood analysis using Khimti Khola, G.S. 650) ............... 33 4.9.2 Regional Flood Frequency Analysis ........................................................... 34 4.9.3 Flood Frequency Analysis Using WECS-DHM Method ............................... 35 i Upgraded Feasibility Study Report Suri Khola Hydropower Project 4.10 DIVERSION FLOOD ................................................................................. 36 4.11 LOW FLOW ANALYSIS ............................................................................ 36 4.12 SEDIMENT INVESTIGATION AND ANALYSIS .......................................... 37 4.12.1 Sediment yield studies in Nepal ................................................................. 37 Some Assumptions of the Suri Basin .................................................................... 38 4.12.2 Sediment Yield of Nepalese Rivers ............................................................ 38 4.12.3 Estimate of Sediment Yield ....................................................................... 39 4.13 CONCLUSION AND RECOMMENDATION ............................................... 41 5 GEOLOGICAL AND GEOTECHNICAL STUDIES ..................................... 42 5.1 INTRODUCTION ...................................................................................... 42 5.2 OBJECTIVES OF PRESENT STUDY ........................................................ 42 5.3 METHODOLOGY ..................................................................................... 42 5.4 REGIONAL GEOLOGY ............................................................................. 43 5.5 GENERAL GEOLOGY OF PROJECT AREA ............................................. 44 5.5.1 Geomorphology ........................................................................................ 44 5.5.2 River Terraces .......................................................................................... 45 5.5.3 Recent Riverbeds ..................................................................................... 45 5.5.4 Geological Formation ................................................................................ 45 5.6 SEISMICITY ............................................................................................. 45 5.7 GEOLOGY OF PROJECT AREA............................................................... 47 5.7.1 Headworks site ......................................................................................... 47 5.7.2 Settling Basin ........................................................................................... 48 5.7.3 Water Conveyance System ....................................................................... 49 5.7.4 Powerhouse ............................................................................................. 52 5.8 CONSTRUCTION MATERIAL SURVEY .................................................... 52 5.8.1 Tests of Construction Materials ................................................................. 54 5.9 CONCLUSIONS AND RECOMMENDATIONS ........................................... 55 6 PROJECT DESIGN AND DESCRIPTION .................................................. 57 6.1 GENERAL ................................................................................................ 57 6.2 CIVIL WORKS .......................................................................................... 57 6.2.1 Headworks ............................................................................................... 57 6.2.2 Head Pond ............................................................................................... 60 6.2.3 Water Conveyance System ....................................................................... 60 6.2.4 Powerhouse and Tailrace .......................................................................... 60 6.3 HYDRO-MECHANICAL WORKS ............................................................... 61 6.3.1 Steel Penstock Pipe .................................................................................. 61 6.3.2 Base Plates & HDPE sheet ....................................................................... 62 6.3.3 Expansion Joints ...................................................................................... 62 6.3.4 Gates and stoplogs ................................................................................... 63 6.3.5 Trash Racks ............................................................................................. 64 6.4 ELECTRO-MECHANICAL EQUIPMENT.................................................... 64 6.4.1 Turbine....................................................................................................