SESSION-16: College Students
PAPER-11: Redesigning of Storm-water Drains Leading to Kukkarahalli Lake
and Suggesting Mitigative Measures - A Case Study
Nisha.S, Mamatha a.s. and Pavithra.M.

Abstract:

Storm-water drains are designed mainly to control the quantity, quality of runoff, resulting from storm events. Stormwater drains are also designed for erosion control, boosting natural ground water table, prevention of eutrophication and safeguarding other aquatic bodies life, enrichment of fresh water resources, maintenance of hygiene and aesthetic appeal of the lake. In order to achieve the above goals, a detailed study of the existing stormwater drains leading to kukkkarahalli lake was carried out and it was found out that 3 out of 4 drains required redesigning. 

The catchment area was divided into 3 subcatchments, district A, district B, district C, having an area of 37.5 ha, 75 ha and 75 ha each respectively. The peak discharge was found to be 8.43 cum, 16.87 cum and 16.87cum respectively. The depth of flow was calculated and was found that all the drains A, B and C had sufficient total depth to carry the discharge, whereas drain D was short by 0.82 m. Hence redesigning is done to increase the total depth of the drain. 

In the next aspect, it was observed that actual shape of the drain was not maintained due to erosion. It was found that drain A was completely distorted for about a length of 315 m, and drain B has lost its shape at different chainages. Hence by retaining the bedwidth and side slope the same as the existing. Redesigning with respect to earth filling and earth cutting was done as per the redesigned data. As the result of redesigning, an additional flow of 15 cum can be allowed to the lake along with the present inflow, which helps to increase the fresh water resource in the lake.