2019 Flash Flood Early Warning System for North Eastern Part of Bangladesh FINAL REPORT DECEMBER 2019 i Government of the People’s Republic of Bangladesh Ministry of Water Resources Bangladesh Water Development Board Flood Forecasting and Warning Centre Flash Flood Early Warning System for North Eastern Part of Bangladesh Final Report December 2019 FLASH FLOOD EARLY WARNING SYSTEM FOR NORTH FINAL REPORT EASTERN PART OF BANGLADESH DECEMBER 2019 ii Institute of Water Modelling House # 496, Road # 32, New DOHS Mohakhali, Dhaka-1206, Bangladesh Phone: (8802) 9844590, 9847902, 9842105 Fax: 9847901, Web: www.iwmbd.org Flood Forecasting & Component Project Director Warning Center (FFWC), HILIP-BWDB Part & Executive Bangladesh Water Engineer, Flood Forecasting & Client's Client: Development Board Warning Center (FFWC), Bangladesh Contact: (BWDB) Water Development Board (BWDB), WAPDA Building (8th Floor), Motijheel C/A, Dhaka-1000 Project Title: Flash Flood Early Warning System for Project No. 51521 North Eastern Part of Bangladesh Division: Flood Management (FMG) Date: 15 December, 2019 Contributors Md. Sohel Masud (Director, FMG) Approved by: Md. Yusuf Mamun (SS, FMG) Tarun Kanti Magumdar (SS, FMG) Abdulla Hel Kafi (SS, FMG) Md. Tohidul Islam (AS, FMG) Md. Mahbubur Rahman (AS, ICT) (Abu Saleh Khan) Tashrifa Sultana (AS, FMG) Deputy Executive Director (Opn.) Md. Shahadat Hossain (AS, FMG) IWM Fouzia Khanam (JE, GIS) Report type: Final Report Author Checked by: Tarun Kanti Magumdar (Md. Sohel Masud) Director, Md. Shahadat Hossain Flood Management Division, IWM Key words: Flash Flood, Forecast Station, Forecast Classification: Bulletin, QPF, Pre-monsoon Danger Open Level. Internal Restricted within the parties concerned✓ Confidential This report has been prepared by Institute of Water Modelling (IWM) for FFWC, Bangladesh Water Development Board (BWDB) for their sole and specific use. The report is restricted within the parties concerned. Any other person who uses any information contained herein does so at his or her own risk. FLASH FLOOD EARLY WARNING SYSTEM FOR NORTH FINAL REPORT EASTERN PART OF BANGLADESH DECEMBER 2019 iii Contents List of Figures .............................................................................................................................................. v List of Tables ............................................................................................................................................. vii Acronyms & Abbreviations ........................................................................................................................ ix Glossary x EXECUTIVE SUMMARY ............................................................................................................................... xi 1. INTRODUCTION .................................................................................................................................. 1 1.1 Background .................................................................................................................................... 1 1.2 Objectives ....................................................................................................................................... 3 1.3 Scope of Works .............................................................................................................................. 3 1.4 Study Outputs ................................................................................................................................ 4 1.5 Structure of the Report .................................................................................................................. 5 2. DATA COLLECTION AND ANALYSIS ..................................................................................................... 6 2.1 General ........................................................................................................................................... 6 2.2 Primary Data Collection ................................................................................................................. 6 2.2.1 Water Level Data from Auto-gauges .......................................................................................... 6 2.2.2 Discharge Measurements for Rating Curves .............................................................................. 9 2.2.3 Cross-Sections Survey ..............................................................................................................13 2.3 Secondary Data Collection ........................................................................................................... 15 2.3.1 Hydrometric Data .....................................................................................................................15 2.3.2 Indian Cross-Border Data .........................................................................................................20 2.4 Bench Mark Connection and Conversion to m MSL Datum ......................................................... 22 2.5 Pre-monsoon Danger Level .......................................................................................................... 26 2.6 BMD Radar Rainfall ...................................................................................................................... 29 2.7 Haor Database Management System .......................................................................................... 31 3. FLASH FLOOD FORECAST MODEL ..................................................................................................... 32 3.1 General ......................................................................................................................................... 32 3.2 Review of Past Models ................................................................................................................. 32 3.3 Updating of Flash Flood Forecast (FFF) Model ............................................................................. 35 3.3.1 Rainfall-Runoff Model ..............................................................................................................35 3.3.2 Hydrodynamic Model of North-East Bangladesh .....................................................................39 3.3.3 Hydrodynamic Model of Barak Basin .......................................................................................42 3.3.4 Flood Forecast Module (FF) .....................................................................................................45 3.4 Calibration and Validation of FFF Model ...................................................................................... 47 3.4 Weather Research and Forecast Model ....................................................................................... 57 FLASH FLOOD EARLY WARNING SYSTEM FOR NORTH FINAL REPORT EASTERN PART OF BANGLADESH DECEMBER 2019 iv 3.4.1 WRF Model Applied by IWM ....................................................................................................58 3.4.2 WRF Model Developed by BMD...............................................................................................62 3.5 Forecast Performance Evaluation ................................................................................................ 63 4. FLASH FLOOD FORECAST PRODUCTS & DISSEMINATION ................................................................ 79 4.1 General ......................................................................................................................................... 79 4.2 Automatic Flash Flood Forecast System ...................................................................................... 79 4.3 Forecast Hydrograph and Bulletin ............................................................................................... 87 4.3 Quantitative Precipitation Forecast (QPF), Outlook and Summary Bulletin ................................ 91 4.4 Embankment Based Forecast ....................................................................................................... 95 4.5 Website and Mobile Apps for Forecast Dissemination ................................................................ 98 5. TRAINING AND TECHNOLOGY TRANSFER, WORKSHOPS AND FIELD VISITS ................................... 105 5.1 Intensive Training on Developed System ................................................................................... 105 5.2 Training on WRF Model .............................................................................................................. 107 5.3 On-the-Job Training of FFWC Professionals ............................................................................... 108 5.3 Gauge Readers Training ............................................................................................................. 109 5.5 Dissemination Workshop ........................................................................................................... 110 5.5.1 Netrokona Workshop .............................................................................................................111 5.5.2 Habiganj Workshop ................................................................................................................111 5.5.3 Sunamganj Workshop ............................................................................................................112 5.6 Field Visits .................................................................................................................................. 115 6.