Measure to reduce evaporation losses from reservoir
1. Surface area reduction
If the exposed surface area is reduced the evaporation can be put under control.
It is possible to reduce the surface area by adopting following measures:
(a) The reservoir site may be selected in such a way that area to storage ratio is minimum.
(b) To avoid water loss water could be stored below ground.
(c) When there are number of reservoirs on one river the water may be stored in one large reservoir when possible rather than in several small reservoirs.
2. Covering water bodies
Covering the surface of water bodies with a fixed or floating covers considerably reduces evaporation losses. These covers reflect energy inputs from the atmosphere and create a layer that prevent transfer of water vapour to the atmosphere. Fixed covers have been used for small and medium storage.
3. By spreading surface films on the reservoirs and lakes
Though still under experiment stage this method when used will prove to be most economical and of practical utility. The method is based on the principle that a thin layer of oil film when spread on the water surface is capable of reducing evaporation to significant extent.
4. Wind Shields
The velocity of the wind is directly proportional to the rate of evaporation. So, if the velocity of wind near the surface of the reservoir is reduced, by creating obstruction (like plants around the banks of the reservoir), the rate of evaporation will be put under control. This is an eco-friendly method.
