Abstract :
Knowledge of evaporation losses is important as it may be a deciding factor in the water availability of many of the water bodies in tropical and subtropical regions. In the present study evaporation losses and their relative significance in the overall water budget of Sukhna Lake in India have been studied. Evaporation has been estimated using Penman-Monteith method and its relative contribution has been studied using water balance of the lake. During the study period average monthly evaporation rate was found to vary between 2.03 mm/d for January to 10.21 mm/d during May. The total volume of water lost through the process of evaporation from the lake varied from low losses of 8.87 Ham in January 2012 to high losses of 40.93 Ham during May 2013. The volume of water loss was found to depend not only on the rate of evaporation but also on the water availability in the lake which determines the water spread area of the lake. The contribution of evaporation losses in total losses from the lake in different months was found to be different. The contribution depends on relative contribution from other losses. The losses were as high as about 95% during 2012 summer and were comparatively lower during 2013 summer. Comparative analysis of evaporation losses in total losses from the lake in monsoon and post-monsoon seasons indicates that evaporation losses could vary between 48-90%, depending upon the relative contribution from seepage, which is higher at higher lake water levels and negligible below the water level of 351.74 m above mean sea level. The study concludes that evaporation losses are a deciding factor in total water losses from the lake during deficit rainfall year. However, its relative significance is reduced due to seepage losses in a normal rainfall year.
Keyword :
Evaporation; Penman-Monteith Method; Sukhna Lake; Water balance.