Government of India DFID Ministry of Water Resources, River Development and Ganga Rejuvenation Asian National Water Mission Development Bank Central Water Commission Policy and Advisory Technical Assistance 8089 IND Phase II Operational Research to Support Mainstreaming of Integrated Flood Management under Climate Change Volume 5b Modelling Report Brahmani-Baitarani, Odisha Final December 2015 Deltares in association with RMSI and JPS Operational Research to Support Mainstreaming Integrated Flood Management in India under Climate Change Vol. 5b Modelling Report Brahmani-Baitarani – Final December 2015 Cover: SOBEK Schematisation Brahmani-Baitarani River ii Operational Research to Support Mainstreaming Integrated Flood Management in India under Climate Change Vol. 5b Modelling Report Brahmani-Baitarani – Final December 2015 CONTENTS Abbreviations .................................................................................................................................. vii Units ............................................................................................................................................... viii Chapter 1 Introduction ................................................................................................................. 1 1.1 Flood Risk Modelling and Mapping .................................................................................. 1 1.2 The role of the consortium............................................................................................... 1 1.3 The purpose of probabilistic analysis ............................................................................... 2 1.4 Outline .............................................................................................................................. 2 Chapter 2 Basin description: Brahmani-Baitarani ........................................................................ 3 2.1 Brahmani river basin ........................................................................................................ 3 2.2 Baitarani River Basin ........................................................................................................ 6 2.3 Rainfall distribution .......................................................................................................... 6 2.4 Flooding ............................................................................................................................ 6 2.5 Recent floods.................................................................................................................... 8 2.6 Current flood mitigation................................................................................................... 9 2.6.1 Embankments .......................................................................................................... 9 2.6.2 Storage dams ......................................................................................................... 10 Chapter 3 Topographical data .................................................................................................... 14 3.1 General ........................................................................................................................... 14 3.1.1 River Network ........................................................................................................ 14 3.1.2 Digital Elevation Model .......................................................................................... 14 3.1.3 Bhuvan Cartosat 30m DEM .................................................................................... 15 3.1.4 SRTM DEM ............................................................................................................. 16 3.2 Geography ...................................................................................................................... 16 3.3 Land use ......................................................................................................................... 17 3.4 Inventory of cross sections............................................................................................. 19 3.5 Inventory of modelled structures .................................................................................. 20 3.6 Inventory of civil line elements ...................................................................................... 20 3.6.1 Embankments ........................................................................................................ 20 3.6.2 Roads ..................................................................................................................... 21 Chapter 4 Hydrological models and Rengali reservoir model .................................................... 22 4.1 General ........................................................................................................................... 22 iii Operational Research to Support Mainstreaming Integrated Flood Management in India under Climate Change Vol. 5b Modelling Report Brahmani-Baitarani – Final December 2015 4.2 The Nedbor Afstromnings Model (NAM) concept ......................................................... 22 4.3 Drainage area definition................................................................................................. 22 4.3.1 Catchment delineation .......................................................................................... 22 4.3.2 Sub-catchment delineation.................................................................................... 23 4.3.3 Muskingum routing ................................................................................................ 24 4.4 Calibration approach ...................................................................................................... 26 4.4.1 General................................................................................................................... 26 4.4.2 Selection of calibration periods ............................................................................. 27 4.4.3 Meteorological forcing........................................................................................... 27 4.4.4 Goodness of Fit criteria .......................................................................................... 28 4.5 Calibration ...................................................................................................................... 29 4.5.1 Model input ........................................................................................................... 29 4.5.2 Calibration results of Rengali inflow ...................................................................... 30 4.5.3 Evaluation of GoF criteria ...................................................................................... 31 4.6 Validation ....................................................................................................................... 32 4.6.1 Model input ........................................................................................................... 32 4.6.2 Validation results of Rengali inflow ....................................................................... 32 4.6.3 Evaluation of GoF criteria ...................................................................................... 33 4.7 Conclusions on calibration and validation ..................................................................... 33 Chapter 5 1D/2D Hydrodynamic model ..................................................................................... 35 5.1 Introduction ................................................................................................................... 35 5.1.1 Integrated 1D/2D modelling .................................................................................. 35 5.1.2 Rationale for model selection ................................................................................ 35 5.2 Setup of the 1D/2D hydrodynamic model ..................................................................... 37 5.2.1 The schematised river system ............................................................................... 37 5.2.2 Cross-sections ........................................................................................................ 38 5.2.3 Structures............................................................................................................... 39 5.2.4 Overland flow......................................................................................................... 39 5.2.4.1 Digital Elevation Model (DEM) preparation ...................................................... 39 5.2.4.2 Line elements..................................................................................................... 40 5.2.4.3 Friction ............................................................................................................... 41 5.2.5 Boundary conditions .............................................................................................. 43 5.2.6 Sea boundaries ...................................................................................................... 43 iv Operational Research to Support Mainstreaming Integrated Flood Management in India under Climate Change Vol. 5b Modelling Report Brahmani-Baitarani – Final December 2015 5.2.7 Initial conditions .................................................................................................... 45 5.2.8 Salt intrusion .........................................................................................................