REVIEW ON THE IMPORTANCE OF COASTAL RESERVOIRS AND THE FUTURE ASPECTS OF COASTAL RESERVOIR IN BANGLADESH
India is a sub-continent, a major fraction of the population of which remains in the water starved parts of the country which is estimated as 320 million people presently. According to the prediction of United Nations, this number can go upto 840 million by 2050. Though there is no significant change in the rainfall pattern, many parts of the country are victims of droughts every year due to a massive demand-supply mismatch. The major causes for this problem are drastic increase in population every year and insufficient management of the received precipitation. According to the WHO/UNICEF Joint Monitoring Program (JMP) (2012 Update), about 780 people lack access to an improved water source. Due to non-uniformity in the rainfall events, it is difficult to pre-plan large scale water storage at specific locations. Though India has availability of about 4000 billion cubic metres of freshwater, obtained from annual precipitation, a major portion of this water flows into the sea as runoff. So there is an urgent need for storing the monsoon water in coastal reservoirs, so that water from these reservoirs can be supplied to areas facing droughts or having insufficient rainfall throughout the year. Coastal reservoir aims at building a storage structure near the mouth of a river. It mainly focuses upon storage of the runoff. It helps in storage of the flood water that can be used for irrigation, domestic, agricultural purposes etc. The construction of a coastal reservoir does not involve risks and disadvantages, as compared to those faced by inland reservoirs. To connect these reservoirs, a new innovative concept is added, i.e, the concept of Sarovarmala - a chain of coastal reservoirs, inter–linked with each other, having the power to ensure water availability to different parts of India round the year. This system involves no land, forest submergence like that of inland reservoirs. Coastal reservoirs have been constructed in Netherlands, Singapore, Hong Kong, China, England, India, Japan etc.
In India, the Kalpsar Project in Gujarat has emerged as a well planned coastal reservoir with a length of 30 km, live storage of 10000mcm, spread over an area of 2000 sq.km. It has a life span of 300 years.
Like India, Bangladesh has also got some water scarcity issues, though numerous rivers including tributaries flow through the country, constituting a waterway of total length of around 24,140 km. Bangladesh is dominated by the Ganga - Brahmaputra delta. When it flows out of India, the Ganges’ main channel becomes Padma River and combining with the Teesta River, the Brahmaputra river channel becomes Jamuna river. Finally, both the rivers combine to form Meghna which falls into the Bay of Bengal. This huge water is to be utilized to meet the uprising need for water in Bangladesh.
Keywords: coastal reservoir, dam, storage, Shanghai, Marina Barrage, kaptai dam