Evaluation of Some Mathematical Models for Estimating Evaluation of Some Mathematical Models for Estimating

Quantifying evaporation from bare soil is critical for water resources development in arid regions and for bare or fallow agricultural land. Some researchers have commented on typical characteristics of arid regions most potential evaporation is extremely high and available water is limited, thus emphasizing the need for accurate and robust potential evaporation models. The purpose of this paper is to review the abilities of three models to describe diurnal variation of potential evaporations over bare soils. The models discussed are the Penman – Brutsaert, Priestley and Taylor and the advection aridity-actual evaporation model by Brutsaert and Stricker. These three models require atmospheric measurements at only one level and no calibration of surface properties is required. The critical results of the application of these models showed that under a variety of atmospheric conditions Penman-Brutsaert model gave the best description of the measured fluxes. Priestley – Taylor with α = 1.26 performed best under unstable atmospheric conditions especially where radiation is the primary mechanism forcing the evaporation. The Advective – Aridity equation, which relies on complementary relationship between actual and potential evaporation, and could underestimate evaporation but performed best at higher wind speed. Keywords : Evaporation, Water Vapour, Bare soil, Models Journal of Applied Science, Engineering and Technology Vol. 6 (1) 2006 pp. 81-86