Thamarai Kulam (Kavangarai)
This pond was known as Thamarai Kulam in the olden days when the water was filled with the growth of lotus flowers. Then as the time passed, and the area was subjected to changes and development, the pond was named as kavangarai. The pond has in-situ catchment. When this water body was identified by GCC, it was evident that the waste water flow can be avoided and the pond can be brought to its original form. Now the pond is fully restored under the Chennai Smart City Project funds
AREA: 5260.918000000001 Sq.mtrs ZONE: 3 DIVISION: 22
This pond is in Division 22 of Zone 3 and is located on the Valluvar Street, Kavangarai. It is located to the North of the road. The pond is located at North Latitude 1310'16.57"and East Longitude 8011'48.81".
The pond is roughly rectangular in shape. There is water in the pond at the time of survey. There is no revetment, inlet, outlet or steps provided in the pond. The pond is covered by compound wall on three sides with the road on one side. The bund is encroached. The water spread is under encroachment. Earlier sullage was diverted into the pond but stopped about an year back with the local communities initiative. The surrounding houses on the bund still diverts sullage into the pond. The water spread area is infested with weeds. At present, there is no specific catchment to the pond but for its own in-situ catchment. Shallow wells and borewells are the common groundwater extraction structures in the area. The depth of well varies from 5 8m and that of the borewell from 30m to 40m below ground level (bgl). The depth to water level is at around 1.5m bgl. Based on the interaction with the local community, it is inferred that the local youngsters wanted the pond to be closed and converted as a play ground. Based on the Total Station Survey output, it is inferred that the total area of the pond is 5163.908 sq.m and the total length of the bund is 307m and the depth as about 1m.
The imagery extracted from google earth on 21.03.2016 and 07.05.2007 is presented below shows no appreciable change but at site it is evident that the pond is subjected to severe dumping of solid waste and liquid waste diversion.
Google Image of the pond as on 21.03.2016 (LEFT) and 01.06.2002 (RIGHT)
The actual volume stored in the tank during 1987 a normal rainfall year - after losses due to evaporation and recharge is given in the following Graph.
The total storage of the tank in its present condition is estimated at 5163.908 cu.m Based on this estimate, there will be water available in the pond for almost 131 days in a year. At no point of time, the pond overflows in a normal rainfall year. The total inflow to the tank in a normal rainfall year is estimated at 49,814.48 cu.m; the net groundwater recharge in a normal rainfall year is estimated at 5455.69 cu.m. The estimate made for an excess rainfall year is presented below :
Based on this estimate, there will be water available in the pond for 139 days. The pond in its present volume does over flows for less than a week in an excess rainfall period for the assumed catchment. The total net inflow to the tank in an excess normal rainfall year is estimated at 424,761 cu.m; the total groundwater recharge is 6051.61 cu.m.
Based on the field observations and inferences, followed by the data analysis, following were the list of activities proposed for renovating the pond.
- The sullage diversion and solid waste dumping should be stopped first
- The waste water in the pond should be dewatered and disposed.
- The pond can be desilted and cleaned in the water spread area. evetment need to be provided with toe wall and binding wall along with steps.
- Bund should be formed all around the pond and strengthened;
- Bush clearance all around the pond should be done
- The pond should be provided with a proper fence with a gate