A study of drainiage systems for selected cities in Bangladesh

Abstract

The planning and design of urban drainage system can not be successfully conducted without a variety of supporting data relating to the locality of the actual project as well as to the entire region that will be benefited or affected by the project. The drainage design should provide a balanced combination of natural and man-made drainage elements which offer an adequate flood protection for urban developments and minimize drainage impact on receiving waters. It has been noted that although there has been substantial progress made in development of design tools, the progress in the availability and acquisition of supporting data is lacking. Therefore, this study is concentrated on the acquisition of supporting data such as climatic condition, urbanization pattern, topography of land, surface water availability and socio-economic condition of Bangladesh. After conducting the survey on the existing drainage system in the selected towns, the problems were identified and summarized. Some probable solutions are also proposed to overcome the problems and difficulties. These will help in designing and taking decision in the field, in this regard. A new concept on the shape of drain has been suggested to construct the drains in flat areas which allows to flow sullage more efficiently. This shape provides better self cleansing velocity to the sullage flow. Run-off coefficient for some selected areas in Bangladesh have been determined, this may help in assuming run-off co-efficient for any area. Attempt is being made to identify the cost effective drain, over ditch or pond to minimize construction difficulties.