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information. More data <strong>and</strong> information <strong>of</strong> the basin were available in different organizations <strong>and</strong> publications, which <strong>of</strong>fered further scope <strong>of</strong> development. Tracing <strong>of</strong> Rivers All Tributaries <strong>of</strong> the Ganges <strong>and</strong> Brahmaputra rivers were traced using tool <strong>of</strong> MIKE BASIN. The traced river alignments were somewhat different from that procured from different maps <strong>and</strong> GIS data sets. However, this difference did not entertain any discrepancy in the simulation <strong>of</strong> model. Delineation <strong>of</strong> Sub Catchments Sub catchments <strong>of</strong> the GBM basin were re-delineated using version 3 Digital Elevation Model (DEM) developed by USGS based on SRTM data. The new DEM (3 Arc-second grid) was more representative than previous GTOPO30 DEM (30 Arc-second grid). Sub Catchments were delineated considering variability <strong>of</strong> topography, hydrometeorology <strong>and</strong> l<strong>and</strong> use pattern in the basin area. The GBM basin model comprises 95 sub catchments out <strong>of</strong> which 33 were in Brahmaputra basin, 55 were in Ganges basin <strong>and</strong> the rest 7 were in Meghna basin. Model Boundaries Rainfall <strong>and</strong> evaporation are requisite boundaries for rain fed sub catchments. Rain fed catchments subjected to irrigation require irrigation records which were ignored in this study. Temperature data were incorporated as additional boundary for snow fed catchments. Simulation <strong>of</strong> Base Model Base model was simulated for three rainfall data sets: TRMM satellite rainfall, Gatech rainfall was used in CFAN project, <strong>and</strong> mixed rainfall data were obtained through processing <strong>of</strong> ground measured rainfall filling missing period or location with TRMM rainfall. Model simulation was continued from 2004 to 2007. Calibration & Validation <strong>of</strong> Model The GBM Basin model has been calibrated using round the year hydrological feature <strong>of</strong> 2005. The model has been validated for two subsequent years (2006 <strong>and</strong> 2007). Sample plots <strong>of</strong> calibration <strong>and</strong> validation have been shown in the Figure 2.1. Simulated run<strong>of</strong>f <strong>of</strong> the Ganges basin was compared with measured discharges at Hardinge Bridge on the Padma river. It is observed that simulated run<strong>of</strong>f could not closely follow the measured discharge, rather there is disagreement in phase <strong>and</strong> magnitudes. Simulated discharge follows the trend <strong>of</strong> rated discharge for bulk <strong>of</strong> the simulation period. During July to September period, simulated monthly flow volume differs from actual by ranging from (-) 8 % to (+) 20 %. It is anticipated that consistent rainfall <strong>and</strong> evaporation inputs would improve the performance <strong>of</strong> model. Measured discharges at Bahadurabad on the Brahmaputra river were compared against simulated run<strong>of</strong>f <strong>of</strong> the Brahmaputra basin. Simulated flow was found in satisfactory agreement with the observed data. 18
Run<strong>of</strong>f (m 3 /s) Run<strong>of</strong>f (m 3 /s) Figure 2.1: Simulated <strong>and</strong> Observed flow <strong>of</strong> the Brahmaputra Basin at Bahadurabad 2.2.2 Bay <strong>of</strong> Bengal Model The s<strong>of</strong>tware used for the development <strong>of</strong> the mathematical model <strong>of</strong> Bay <strong>of</strong> Bengal is MIKE21 FM module <strong>of</strong> DHI Water <strong>and</strong> Environment. The MIKE 21 FM model system is based on an unstructured flexible mesh consisting <strong>of</strong> linear triangular elements. Hydrodynamic Model The numerical hydrodynamic model is founded on a combination <strong>of</strong> specific regional information (data) <strong>and</strong> a generic numerical modelling system MIKE 21 FM. A 2D depth integrated numerical model <strong>of</strong> the Meghna Estuary <strong>and</strong> Bay <strong>of</strong> Bengal have been applied. The coverage <strong>of</strong> the model area starts from Ch<strong>and</strong>pur on Lower Meghna river to 16 0 Latitude in the Bay <strong>of</strong> Bengal. The model applies PWD datum, i.e. level 0.46m is MSL. The grid or mesh size decreases (or the resolution increases) towards coastlines <strong>and</strong> isl<strong>and</strong>s. Inter-tidal areas are flooded <strong>and</strong> dried during a tidal cycle, both in nature <strong>and</strong> in the model. Two open boundaries are identified in the model, one in the north in the Lower Meghna River at Ch<strong>and</strong>pur <strong>and</strong> one in the south in the Southern Bay <strong>of</strong> Bengal. The Bay <strong>of</strong> Bengal is quite deep <strong>and</strong> the maximum depth along the southern open boundary is more than 2000m. 19
Page 1: Impact Ass
Page 4 and 5: Impact Ass
Page 7: Foreword The impacts of</st
Page 11 and 12: Table of Contents
Page 13: List of Figures Fi
Page 16 and 17: Sea level rise for
Page 18 and 19: E.5 IMPACT OF CLIMATE CHANGE ON MON
Page 21 and 22: 1. INTRODUCTION 1.1.1 Background Ba
Page 23 and 24: 1.3 Review of Past
Page 25 and 26: affected more and
Page 27 and 28: was to reduce the vulnerability <st
Page 29 and 30: 2. DATA and MODEL
Page 31 and 32: The Yamuna The Yamuna (sometimes ca
Page 33 and 34: Ganges Basin The Upper Ganges basin
Page 35 and 36: The southwest summer monsoon, a fou
Page 37: seconds (0.008333333333333 degrees,
Page 41 and 42: Figure 2.4: Calibration of<
Page 43 and 44: tidal estuary systems, the largest
Page 45 and 46: unoff catchments w
Page 47 and 48: Historic peak flow record o
Page 49 and 50: 5. BASELINE CONDITION OF MONSOON FL
Page 51 and 52: Sirajganj: Sirajganj is situated on
Page 53 and 54: Table 5.6: Inundated area in modera
Page 55 and 56: Model results were analyzed to find
Page 57 and 58: Sunamganj: The total area o
Page 59 and 60: Jamuna river. It is also seen that
Page 61 and 62: Figure 6.1: Inundated Area Base Con
Page 67 and 68: Impact on l<strong
Page 69 and 70: according to 4 th IPCC, in reality
Page 71 and 72: REFERENCES 1. 4 th IPCC (2007), Reg
Page 73: Appendix-A Impact
Page 76 and 77: Table A.2: Impact
Page 83: Appendix-B Impact
Page 86 and 87: Figure B3: Inundated Area Base Cond
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Figure B7: Inundated Area Base Cond
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Figure B11: Inundated Area Base Con
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Table C1: Change <
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