TR-14 : Estimating evaporation losses from lakes and reservoirs

Abstract

Engineers, planners and all concerned with water resources require an estimate of evaporation losses from lakes and reservoirs for the efficient reservoir operation and the water balance studies, specially in arid and semi arid regions and in drought affected areas While designing drought alleviation schemes. The exhaustive and detailed review of literature indicates that the methods of mass transfer and Penman equation can be considered as good alternative to provide relatively better estimates of evaporation losses from lakes and reservoirs in the absence of large amount of data required for the energy budget method. The evaporation losses obtained for Bhadra Reservoir Project by using mass transfer method generally points towards a lower value. Estimates obtained by Penman method appear to be relatively more reliable and in this method pan coefficient is also relatively more in winter period (i.e.0.99) as compared to that of summer period (i.e.0. 88) Which is same as the normally accepted trend.