The validity of mathematical and computer models for estimating the non-steady evaporation from bare soil surface using evaporation evaluation field operations

Subject Areas : environmental management

Ali Neshat ¹ , Mansour Parehkar ²

1 - Assistant Professor, Islamic Azad University, Kerman, Iran
2 - Assistant Professor, Soil Conservation & Watershed Management Research Institute

Received: 2007-11-01 Accepted : 2008-03-03 Published : 2009-09-23

Keywords: Bare soil evaporation, non-steady evaporation, LEACHM computer model, Richard’s&#x0D, &#x0D, Equation, water balance model,

Abstract :

The main problem for the exact estimation of evaporation in field conditions is the lack of basic relations with the least amount of information needed for considering water loss in water balance models. The main goal of this study is to examine the available methods of evaporation calculation from bare soil surface and to suggest the best method. Most of these relations are empirical; to deduce them, simplifying hypotheses have been used to analytically solve the Richard’s equation with relatively constant border and initial conditions which don’t have a physical basis. In regions where the ground water surface is low, the results of these relations do not coincide with reality. Evaporation from bare soil area was calculated through the numerical solution of Richard’s equation in a one-dimension, non-steady form with border and initial conditions different from those of other methods using computer LEACHM model. There is a strong relationship between the results of the computer model and the water balance model carried out using field experiments in certain time intervals and specific areas.