Sukhna Lake catchment area filled with too many reservoirs: Study

The study was given to SPACE,a city-based NGO,through the Directorate of Environment. The report of the findings is being prepared and is likely to be ready by next month.

The water retention capacity of the reservoirs and its impact on Sukhna Lake has been an issue of constant debate in the city. The NGO was,therefore,assigned

the task of finding out the amount of water being retained in

the reservoirs.

Spanning over a period of one year,the members of the NGO measured the water levels in the reservoirs at different intervals of time. It was found that by the end of September,the capacity of the reservoirs was at its peak. Data has also been collected on the period when the water fills the reservoirs and then overflows to enter Sukhna Lake.

The study covers 154 reservoirs built in the catchment of the lake,of which 27 were found to be completely filled with silt. These would need to be desilted.

In fact desilting of all the dams needs to be carried out at regular intervals so that these remain functional. It was also found that some of the reservoirs had developed leakages,which was leading to seepage of water.

SPACE Chairman Dr S S Grewal said that this is the first time such an extensive study of the capacity of the reservoirs has been undertaken.

“The issue of water retention capacity of the reservoirs and the impact on the lake has been much debated. We have collected data on the capacity of all the

reservoirs. These reservoirs were found to be well-made. However,there are too many of these reservoirs that have been built. At every 17 to 18 hectares,one dam has been made. We will be making recommendations pertaining to the dams in the report,” said Dr Grewal.

When the lake was created in an area of 2.28 sq km in 1958,its water-bearing capacity was 10.74 million cubic metres and water inflow was 8,310 acre feet. In the first 20 years,the inflow decreased to 7,370 acre feet.

The Shivaliks,known to be the most erodable hills,led to a large amount of silt entering the lake. When the problem was realised in 1975,silt retention dams were created in the catchment area.

Dr Grewal said that the Sukhna basin is floating on water. Some of this could be released into the lake.

Wildlife in the catchment area would be able to sustain themselves even if the water maintained in the reservoirs is around 2 to 3 feet.

This would add more water to Sukhna Lake.