Final Evaporation Control in reservoirs

8.2
 
Other Evaporation Retardation Measures 
8.2.1
 
Compartmentalisation of Reservoirs 
Water harvesting agri-systems or the coupling of artificially collected rain water with 
agriculture and surface storage system, offer a promising way of increasing both the 
quantity and the dependability of water in arid and semi arid lands. The use of 
compartmented reservoir in conjunction with appropriate agri-systems provides a 
relatively low cost and efficient method of storage as compared with conventional 
storage methods. Based on the principle that the division of a conventional reservoir 
into compartments with systematic pumping of water to the deeper compartments can 
achieve evaporation control through reduction of surface area. Few reservoirs were 
analysed by a computer model and it was found that savings of 50-60% can easily be 
obtained (Cluff, 1978). 
8.2.2
 
Floating Granular Material 
Investigations were conducted to determine the feasibility of reducing evaporation 
from open water surfaces with white, floating granular material. These studies were 
conducted on buried 7.2m dia. tanks where almost all energy exchange occur through 
the water surface. Materials evaluated were Calcium Carbonate dust, silica sand, 
polystyrene beads, chopped Styrofoam, and Perlite. Evaporation reduction for one 
week ranged from 21% for silica sand to 64% for chopped Styrofoam (Myers & 
Frasier, 1970). 
8.2.3
 
Floating Rubber Sheets 
Evaporation control for stock tanks in Utah was investigated using floating sheets of 
foam rubber which is highly resistant to weathering and can be formed into a 
continuous cover by lap jointing using contact cement. Evaporation reduction of 
about 75% was achieved by covering 95% of water surface (Dedrick et al., 1973)