Evaporation from the farm pond

Published on by in Business


I am from Asia and after working in industries for 10 years have switched to farming in my area. The area where I live   receives an average of 950 mm rainfall annually and has good potential for run-off harvesting. So I decided to go for a farm pond. Considering the slopes of the fields, an appropriate location was identified for a dug out pond (8m x 8 m x 3 m). We have taken a good care for pitching so the percolation is very less but the evaporation is very high. Can anyone suggest me some economic ways to reduce the evaporation from our farm pond?

4 Answers

  3. hope this info helps you

    Factors affecting Evaporation

    Evaporation from water bodies depends on a number of factors. The main factors affecting evaporation are surface water area, temperature, vapour pressure difference, wind velocity, atmospheric pressure and quality of water. Since evaporation is a surface phenomenon, the quantity of water lost through evaporation is directly proportional to the surface area of water exposed to the atmosphere. In view of this, for conservation of water through evaporation control, efforts need to be made to reduce the exposed surface area of water by various means.

    (i) Evaporation Control Methods

    Evaporation being one of the major causes for loss of water from reservoirs, lakes and tanks, a number of methods have been experimented by engineers and scientists to reduce evaporation losses from water bodies. Since the basic meteorological factors affecting evaporation cannot be controlled under normal conditions, efforts have so far been restricted to managing the suppression or inhibition of evaporation from water surfaces by physical or chemical means. The following methods are generally used for evaporation control:

    1 .Wind breakers;

    2 .Covering the water surface;

    3 .Reduction of exposed water surface;

    4 .Underground storage;

    5.Integrated operation of reservoirs and

    6 .Use of Chemical Water Evapo-Retardants (WERs).

    ( CWC, 1995, Bhagirath - Indian Water Resources Quarterly , Vol. XXXXII, January-March, 1995, pp 11-12)

    Although, the chemical method of evaporation control has certain limitations and disadvantage of its high cost of application in normal conditions, yet this method has evoked maximum attention all over the world as a practical solution for conservation of fresh water. In view of this, chemical WERs have been described in detail. These materials can be used in powder, liquid or emulsion forms.

    (ii) Chemical Water Evapo-Retardants (WERs)

    Compounds in use

    A non-toxic chemical, capable of forming a thin monomolecular film on the water surface is applied, which prevents energy inputs from the atmosphere from reducing evaporation. The film allows passage of enough air through it and thus aquatic life is not affected for want of oxygen. A film formed by fatty alcohols of different grades, is found most suitable for evaporation control.  The compounds generally used are Cetyl alcohol or Hesadecanol (C16-H33-OH), Stearyl alcohol or Octadecanol  (C18-H37-OH) and Biphenyl alcohol or Docosanol (C22-H45-OH) or a mixture of these compounds. National Chemical Laboratory (NCL), Pune have developed one more compound by synthesizing Alkoxy Ethanols. All these alcohols should be 99 per cent pure for getting the desired properties of monolayer.

    Long-term evaporation control measures like plantation of trees as wind breakers, reduction of exposed water surface, increasing  the underground storage of water, integrated operation of reservoirs etc. need to be employed. Therefore, it is better to store water underground without letting it to evaporate, pollute, log and get confined to one place. Hence, rain water which is the primary source of water, has to be managed in such a way that there should be maximum utility of it.

  4. Depending on resources available, put at roof over it, on an angle that would be suitable to attach solar panels at a later date. It does not have to be a high roof, just enough for the right pitch. You will still catch all the rain fall as it will run of the roof into gutter into pond. Seal the sides to restrict sunlight. Otherwise make a floating platform from 44 gall drums? join with timber and place a cover over it of some kind. Make peaks in the cover where the drums are so that you create a valley for the rain to run to and drain through, this will also reduce the surface area the sun can see.