The 1996 Ganges Water Sharing Treaty was an important breakthrough in solving disputes over sharing Ganges water between India and Bangladesh. This study evaluates cooperation reflected in the Treaty by performing a quantitative analysis on available water sharing data. The study recognized that inaccurate projection of future flow and the obligation of allocating guaranteed 991 m3/s flows perpetuate the ongoing water sharing conflicts. The provision of guaranteed minimal flow alternately to India and Bangladesh during critical periods leads to frequent occurrences of low-flow events. Results indicated that the Treaty underestimated the impact of climate variability and possibly increasing upstream water abstraction. Statistical analysis of the post-Treaty data (1997–2016) also indicated that 65% of the time Bangladesh did not receive its guaranteed share during critical dry periods with high water demand. It is advised to project the reliable water availability using a combination of modelling and improved observation of river flows. In addition, the condition of minimum guaranteed share should be removed to reduce the frequency of low-flow events in future. Although our analyses show a number of weaknesses, the Treaty could still enhance the future regional cooperation if some adjustments are made to the current terms and conditions.

Bangladesh is prone to severe flooding as being located at the confluence of three mighty rivers named the Ganges, Brahmaputra, and Meghna. As a consequence, river flooding and erosion are common natural disasters that severely affect the landscape, lives and economy of the country. Dharla River, one of the trans-boundary rivers originated in the Himalayas, along with Brahmaputra River has a great influence on the recurring floods and erosion in north-western Bangladesh. Almost in every year, excessive erosion and embankment damages caused by Dharla render a thousand of people homeless with massive loss of crops and poultries. As per the environmentalists, this is a matter of huge concern as development of accurate flood maps and erosion prediction for Dharla River has been very challenging. In this study, the flood map and Dharla River bank shifting study have been developed by using HEC-RAS 4.1.0 hydrodynamic model and Landsat satellite images. In addition, the HEC-GeoRAS was used to establish the river reach for HEC-RAS. The calibration and validation have been performed using the observed and simulated water levels for the years of 2013 and 2014 respectively. The HEC-RAS flood water level output was used in HEC-GeoRAS for raster interpolation followed by overlain onto the land surface elevation of the study area. Then, the difference between water level interpolation and land elevation surfaces has been considered as a depth of inundation which is performed in Arc-Map 10.2. Flood maps have been generated for the years 2010, 2013, and 2014 for highest water level of each year. The erosion prone areas have been indicated by analyzing bank shifting of Dharla River for the years 1987, 1997, 2007, and 2017 by digitizing the satellite images in Arc-GIS 10.2. From the observation it has been found that the course of the Dharla River has been shifted vastly since 1987 to 2017 due to erosion.

Climate change is the burning issue and utmost environmental challenge for the world today and Bangladesh is considered as the most vulnerable in recent days. Besides, due to its geophysical setting Bangladesh coast is frequently visited by the cyclone-induced storm surge. The assessment of impact of climate change induced cyclonic storm surge and evaluation of potential adaptive measures requires use of scientifically based and tested state-of-the-art mathematical modelling tools. In this study SIDR (a severe cyclone that hit the coast of Bangladesh in 2007) has been selected to assess the vulnerability of selected two islands Sandwip and Kutubdia. Three different tracks were simulated to assess the effect of position of Landfall for each island. It is evident from the model results that if SIDR comes with 0.59m Sea Level Rise (SLR) and 1.0m SLR during high tide, maximum surge height above land level will be 5.1 m and 5.5 m for Kutubdia island and 6.5 m and 6.9 m for Sandwip island respectively. If the same cyclone comes with 10% increased wind speed during high tide with 59 cm SLR, surge height may increase by 0.9 m for Sandwip island and 0.45m for Kutubdia island. Again, it has been found from the study that 200m, 400m and 600 m width of Mangrove can reduce the surge height by 12 cm, 15 cm and 18 cm respectively. This reduction is not enough but it reduces current speed to one-third from 1.8 m/s to 0.65 m/s at Sandwip island. As it reduces the current speed to a larger extent it is favourable for the stability of the coastal embankment and other coastal infrastructure. In view of the above it is the high time to revisit the coastal infrastructure to make it climate resilient.

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Bangladesh is located at the head of the Bay of Bengal. The coast of Bangladesh is known as a zone of vulnerabilities as well as opportunities which involves coast and island boundaries. The eastern coastal zone consists of sandy beaches and hilly areas and is morphologically very dynamic. This shoreline is an important zone which facilitates tourism opportunity, fishing industry, natural resources and regional highway. Cox’s Bazar-Teknaf shoreline has been experiencing severe erosion at a number of places due to wave action. Wave and wind induced motion results in sediment distribution and shaping of nearshore morphology. The study has been performed by using Remote Sensing and GIS techniques. The shoreline shifting analysis has been performed by the process of open source Landsat images from 1980 to 2017. Satellite derived band algebra; Normalized Difference Vegetation Index has been utilized to identify the vegetation cover. The satellite images of an object carry a unique index property. In this study the index property of vegetation cover has been used to delineate more stable shorelines. At different locations, the average change in shoreline goes up to 120 m in erosion and 100 m in deposition. Based on the coastline shifting the erosion behaviour and the vulnerable areas are identified. Journal of Engineering Science 12(1), 2021, 21-28