The report presents a study on the Sagar lake wherein the various water balance components like inputs and outputs have been quantified to visualize the influence of these parameters on the storage changes. Lakes play an important role in shaping the hydrological, ecological and environmental balance of the region by developing the flora, fauna and habitation of the aquatic biota. Like other lakes, Sagar lake too faces manifold problems of siltation and deterioration of water quality, thus threatening its survival.

Previously most of the scientific studies carried out on Sagar lake have focused on the physico-chemical properties of the lake water and the possible inert-relationship and interaction between their properties and biological factors like plankton, macrophytes, macrofauna etc. Therefore to understand various hydrological processes of the lake, water balance study has been carried out.

The study reveals that the major inflow to the lake is surface runoff, which accounts for nearly 56 per cent of the total annual inflow. Of the total annual inflow, about 98 per cent inflow to the lake takes place during monsoon period. The major outflow component from the lake is weir overflow, which occurs in monsoon season only and accounts for about 85 per cent of the total annual outflow. Of the total annual outflow about 92 per cent outflow from the lake takes place during monsoon period.

Since there is heavy inflow into the lake even with normal rainfall in monsoon season, there will be no scarcity of water to fill the lake up to full tank level in any hydrologic year even if the rainfall is below normal, provided the water withdrawal trend from the lake is not disturbed.

The study makes the following points in conclusion -

• A huge quantity of water overflows every year from the Mogha weir and goes waste. So a storage basin on the downstream side of the nalla can be thought of to utilise the overflowing water.
• Nallahs carrying city waste should be diverted away from the lake. For this, awareness of nearby population and some alternative arrangements for drains would be required.

The outcome of the study will be helpful in proper management of the lake water and in conducting other relevant hydrological studies.

Download the report here: