Hydrography of Dhaka City Catchment and Impact of Urbanization on Water Flows: A Review

Dhaka has one of the fastest urban growth rates of the world with around 12 million people in 2006. It is located on extensive sub-continental floodplains of the Ganges and the Brahmaputra with average elevation of 6 m above mean sea level (MSL). It is surrounded by four rivers with well distributed streams, drainage channels, inland and open waters. Physiographical, spatial and temporal environments of these waters profoundly influence inhabitants' life. Mass shrinkage has occurred during the last four decades due to encroachment and filling-up, man-made changes in elevation pattern and siltation with debris from urban development activities. Groundwater storage is on the verge of mass threat because of increasing pollution of surface waters. Water logging has become every-rainy season phenomenon due to unplanned urbanization. Development activities are required to enhance the water environments safe and sustained, and regulations are needed to be imposed to protect these environments.