Objective of Drainage Plan is to find out present functions of main and secondary drains and natural streams within the Bauphal Pourashava. Secondly, level of encroachment over drainage reservations responsible for flooding, water-logging of neighbourhoods during heavy rains also analyzes. Thirdly, information collects on existing roadside drains including capacities and collected gradients. Since planned development of Pourashava is very much desirable, Drainage Master Plan is necessary to ensure operation and maintenance of the present facilities including new proposal for future. For this, short and long term project improvement plan, area-based drainage master plan is necessary to ensure proper drainage of the Pourashava.

Methodology and Approach to Planning

In implementing infrastructural developments, drainage is generally given less priority and normally considers as last or final steps of development. Such scenario particularly true for Bangladesh. Although different types of drainage infrastructures, among others by far the heaviest impacts on physical infrastructure network. As a result, physical environment, health, hygiene and standard of living suffer seriously. In development projects, Government, Semi-government and Public sector allocate funds. Those funds mostly spends on buildings, roads and other more visible infrastructures, drainage comes as the last item of development. By the time, drainage development starts. Appears shortage of fund, consequently as a matter of policy-do little or do-nothing situation appears. As eyewash very little performs for drainage development. In case of urban development, if drainage not emphasizes, sufferings of the inhabitants will continuously increase with the passage of time.

Drainage development for urbanization starts with drain. Drains are classified as Plot drains, Block drains, Tertiary drains, Secondary drains and Primary drains. Other natural drainage infrastructure is lowland, outfall areas, khals and rivers. Man-made drains are Plot, Block, Tertiary, Secondary and Primary drains and others are natural drainage infrastructures. In planning for drainage network, care has given on road network in terms of conflict of drainage and waterways with roads. Drainage and environmental survey follows a proto-type questionnaire.

Natural Drainage System

The natural drainage network is composed with 5 canals plying within the Pourashava. Those canals are flowing towards north to south. Covered area of those canals are 32.98 acres and length 1692.83 meter. An important canal named Kalaia flows on the northern part from west to east of the Pourashava. Generally, over the year, this canal came to calm. During monsoon, all drainage water release through this canal and becomes flooded almost every year.

Table-12.1: Water Bodies in the Pourashava (area in acre)

Source: Drainage Survey, 2011.

There are linkages between natural and man-made drains. But how much effective and active the linkage is with the poorly maintained man-made drains is a question. Almost half of the depth of the man-made drain is filled with solid garbage; as a result, the channel is not functioning properly.

Five important canals are playing important role in the natural drainage system. Those canals need to be preserved from any type of development activity. All type of encroachment must be controlled for the sake of smooth flow of rain and flood water. Length of the canal is varied from 104.09 meter to 4064.00 meter.