Measurement and Estimation of Evaporation from Water Surfaces: Application to Dams in Arid and Semi Arid Areas in Algeria

Many methods exist for either measuring or estimating evaporation from free water surfaces. Evaporation pans provide one of the simplest, inexpensive, and most widely used methods of estimating evaporative losses. In this study, the rate of evaporation starting from a water surface was calculated by modeling with application to dams in wet, arid and semi arid areas in Algeria. We calculate the evaporation rate from the pan using the energy budget equation, which offers the advantage of an ease of use, but our results do not agree completely with the measurements taken by the National Agency of areas carried out using dams located in areas of different climates. For that, we develop a mathematical model to simulate evaporation. This simulation uses an energy budget on the level of a vat of measurement and a Computational Fluid Dynamics (Fluent). Our calculation of evaporation rate is compared then by the two methods and with the measures of areas in situ.

Authors:

• Malika Fekih
• Mohamed Saighi

Keywords:

• Evaporation
• Energy budget
• Surface water temperature
• CFD
• Dams

References:

[1] Craig, I.P, Mossad, R., and Hancock, N. Development of a CFD based
Dam Evaporation Model. International Symposium on Environmental
Health Climate Change and Sustainability. (2006).
[2] Craig, I.P, Literature Review of Methods for Assessing Dam
Evaporation. Draft report for the Rural Water Use Efficiency Initiative
Evaporation Control Project, NCEA Draft Report, University of
Southern Queensland (2004).
[3] Jones Frank. E. Evaporation of water with Emphasis on Applications
and Measurements, Lewis Publishers, Michigan, USA, 1992.
[4] Oroud I.M, The influence of heat conduction on evaporation from
sunken pans in hot, dry environment. Journal of Hydrology, Vol. 210,
pp. 1-10 (1998).
[5] Martinez. M.J.M, Alvarez Martinez V, Gonzalez-Real M.M., Baille. A.
A simulation model for predicting hourly pan evaporation from
meteorological data. Journal of Hydrology, Vol. 318, pp250-261, 2006.
[6] Fennessey. N. M, Vogel. R.M. Regional models of potential evaporation
and reference evapotranspiration for the northeast USA, J Hydrology,
Vol.184, pp. 337-354.
[7] Saïghi. M, Nouveau modèle de transfert hydrique dans le système
sol- plante- atmosphère, Thèse de Doctorat USTHB, Alger (2002).
[8] Eichinger.W.E., Nichols. J, Prueger .J.H, Hipps. L.E., Neale .C.M.U,
Cooper. D.I, and Bawazir.A. S. Lake evaporation estimation in arid
environments: Final Report, IIHR - Hydroscience & Engineering, IIHR
Report No. 430, University of Iowa, pp1-29, July 2003.
[9] Sartori. E, Convection coefficient equations for forced air flow over flat
surfaces. J Solar Energy, Vol. 80, pp. 1063-1071(2006).
[10] Mosner. M.S. and Aulenbach .B.T, (2003). Comparison of methods
used to estimate lake evaporation for a water budget of Lake Seminole,
southern Georgia and northwestern Florida. Proceedings of the 2003
Georgia Water Resources (2003). Conference, held April 23-24, 2003,
at the University of Georgia. Kathryn J. Hatcher, editor, Institute of
Ecology, the University of Georgia, Athens, Georgia, pp.1-4.
[11] Lewis. J.M. The history behind the Bowen ratio, Bulletin of the
American Society, Vol.76, No.12, December 1995.
[12] Bowen, I.S. 1926 .The ratio of heat losses by conduction and by
evaporation from any water surface. Phys. Rev. 27 779-787.