49-Hydrological study for the rehabilitation of Chetpet Tank Chennai

Abstract

An attempt is made to study the hydrology of Chetpet tank located in Chennai and to recommend designs for rehabilitation. A topographical survey was carried out to study the Cooum river influence. The level difference between the Chetpet tank and Cooum river bed is 5.025 m, which is safe depth upto which the pond can be excavated preventing Cooum river water seepage. The catchment area and existing capacity of the tank was surveyed. Runoff was estimated by SCS method using 22 years of rainfall data, which yields 0.28275 Mm3of runoff. Soil samples were collected and tested to obtain the permeability factor for the analysis of recharge mechanism. The proposed pond depth is 3.4 m upto the layer of sandy-clay with gravel with a recharge rate of 71.594 m3/day. It is suggested to provide 8 numbers of recharge trenches cum shaft for enhancing the recharge rate. The proposed pond, after the rehabilitation will be having the recharge rate as 481.76 e/day, which is 6.73 times higher.