SR-11 : Evaporation reduction measures from water and land surfaces for drought management

Abstract

The evaporation losses from water and land surfaces form a substantial amount. The evaporation loss from shallow lakes and small tanks & reservoirs alone comes to almost 50% of the capacity of the tank. Almost one-fourth to one-half of the water lost from a cropped area is through evaporation from the soil surface. Evaporation reduction from water and soil surfaces is one of the supply oriented drought management measures as it conserves water and enhance or augment available water supplies without creating a new sources of water supply in drought prone areas. The use of commercially available Water Evaporation Retardant Chemicals (WERCs) has been demonstrated by various State Governments and research organisations in saving water against evaporation from water bodies. Surface mulches with mulching materials like crop residues, grasses, leaf litter, straw, gravel, polythene sheets, asphalt etc. have been tried and tested at different places by research institutes & field organisations to reduce evaporation from soil surfaces in cropped areas by restricting air movement and maintaining high vapour pressure near soil surface. The present status of such studies, limitations, adoptability and usefulness in relation to drought management including recommendations for further research would be discussed in this report under Indian conditions.