ANNUAL FLOOD REPORT 2019 FLOOD FORECASTING & WARNING CENTRE PROCESSING & FLOOD FORECASTING CIRCLE BANGLADESH WATER DEVELOPMENT BOARD Annual Flood Report 2019 Flood Forecasting and Warning Centre (FFWC) Bangladesh Water Development Board (BWDB) WAPDA Building (8th Floor), Motijheel C/A, Dhaka-1000 Phone : 9550755; 9553118 Fax : 9557386 Email ; [email protected] ; [email protected] Web : www.ffwc.gov.bd Editing & Compilation: Md. Arifuzzaman Bhuyan, Executive Engineer, FFWC, BWDB Sarder Udoy Raihan, Sub-Divisional Engineer, FFWC, BWDB Contribution: Md. Alraji Leon, Assistant Engineer, FFWC, BWDB Partho Protim Barua, Assistant Engineer, FFWC, BWDB Preetom Kumar Sarker, Assistant Engineer, FFWC, BWDB Mehadi Hasan, Assistant Engineer, FFWC, BWDB Review: Md. Saiful Hossain, Superintending Engineer, PFFC, BWDB Published by the FFWC, BWDB, Ministry of Water Resources, Dhaka TABLE OF CONTENTS LIST OF TABLES .......................................................................................................................... 5 LIST OF FIGURES ........................................................................................................................ 7 PREFACE ..................................................................................................................................... 10 EXECUTIVE SUMMARY .......................................................................................................... 12 LIST OF ABBREVIATIONS ..................................................................................................... 13 CHAPTER 1 : INTRODUCTION ............................................................................................. 15 1.1. THE PHYSICAL SETTING .................................................................................................................. 15 1.2. THE RIVER SYSTEM ......................................................................................................................... 15 1.3. ACTIVITIES OF FFWC ...................................................................................................................... 17 1.4. OPERATIONAL STAGES BEFORE FORECAST MODEL RUN ................................................................ 19 1.5. NATURE AND CAUSES OF FLOODING ............................................................................................. 20 1.5.1. Causative Factors ............................................................................................................................ 20 1.5.2. Statistics of Flooding ...................................................................................................................... 21 CHAPTER 2 : RAINFALL SITUATION ................................................................................. 22 2.1 MARCH .......................................................................................................................................... 23 2.2 APRIL ............................................................................................................................................. 23 2.3 MAY ............................................................................................................................................... 24 2.4 JUNE .............................................................................................................................................. 25 2.5 JULY ............................................................................................................................................... 26 2.6 AUGUST ......................................................................................................................................... 28 2.7 SEPTEMBER .................................................................................................................................... 29 2.8 OCTOBER ....................................................................................................................................... 30 CHAPTER 3 : RIVER SITUATION ......................................................................................... 38 3.1 THE BRAHMAPUTRA BASIN ............................................................................................................. 38 3.2 THE GANGES BASIN ......................................................................................................................... 41 3.3 THE MEGHNA BASIN ........................................................................................................................ 45 3.4 THE SOUTH EASTERN HILL BASIN ..................................................................................................... 50 3.5 PEAK AND RECORDED HIGHEST WATER LEVELS ............................................................................... 52 CHAPTER 4 : FORECAST EVALUATION, 2019 ................................................................ 77 4.1 EVALUATION CRITERIA OF FORECAST PERFORMANCE ..................................................................... 78 4.1.1 Mean Absolute Error (MAE) ......................................................................................................... 78 4.1.2 Co-efficient of Determination, r2 ................................................................................................... 78 4.2 PRE-DEFINED SCALES TO EVALUATE FORECAST PERFORMANCE ...................................................... 79 4.3 DETERMINISTIC FORECAST STATISTICS AND PERFORMANCE, 2019 .................................................. 79 4.3.1 Deterministic Forecast Performance ................................................................................................ 79 4.3.2 Medium Range (upto 10-days) Probabilistic Forecast Performance ............................................... 90 CHAPTER 5 : INUNDATION STATUS .................................................................................. 90 5.1 BASINWISE INUNDATION STATUS ..................................................................................................... 95 5.2 COUNTRYWIDE INUNDATION 2019 ................................................................................................... 98 CHAPTER 6 : CHARACTERISTICS AND SPECIAL EVENTS OF 2019 FLOOD ........ 106 6.1 Characteristics of 2019 Flood .......................................................................................................... 106 6.2 Special Events of 2019 Flood Season ............................................................................................... 107 6.2.1 The Severe Flood of Brahmaputra-Jamuna River .......................................................................... 107 6.2.2 The Late Monsoon Normal Flood of Ganges River ...................................................................... 111 Annual Flood Report 2019 Page- 3 CHAPTER 7 : RESEARCH AND DEVELOPMENT ........................................................... 114 7.1 Operational Flash Flood Forecasting System for the North-Eastern Region ..................................... 114 7.2 Initiative with Google for Improved Flood Inundation Mapping ...................................................... 114 CHAPTER 8 : CONCLUSION ................................................................................................ 116 ANNEX-1 .................................................................................................................................. 119 ANNEX-2 .................................................................................................................................. 120 ANNEX-3 .................................................................................................................................. 121 ANNEX-4 .................................................................................................................................. 122 ANNEX-5 .................................................................................................................................. 123 ANNEX-6 .................................................................................................................................. 124 ANNEX-7 .................................................................................................................................. 125 ANNEX-8 .................................................................................................................................. 126 Annual Flood Report 2019 Page- 4 LIST OF TABLES TABLE 1.1 :YEAR-WISE FLOOD AFFECTED AREA IN BANGLADESH ................ 21 TABLE 2.1: RAINFALL STATISTICS FOR THE MONSOON-2019 OVER THE FOUR BASINS ..................................................................................................................... 22 TABLE 2.2: SUMMARY OF THE RAINFALL SITUATION DURING THE MONTH OF MARCH-2019 ..................................................................................................... 23 TABLE 2.3: SUMMARY OF THE RAINFALL SITUATION DURING THE MONTH OF APRIL-2019......................................................................................................... 24 TABLE 2.4: SUMMARY OF THE RAINFALL SITUATION DURING THE MONTH OF MAY-2019 ........................................................................................................... 24 TABLE 2.5: SUMMARY OF THE RAINFALL SITUATION DURING THE MONTH OF JUNE -2019 ......................................................................................................... 26 TABLE 2.6: SUMMARY OF THE RAINFALL SITUATION DURING THE