Experimental Research & Numerical Stimulation Of Evaporation On The Condition Of Water Storage Pit Irrigation

Soil moisture evaporation is the important portion of water circle in the nature. The soil evaporation has important position in farmland water balance and energy balance. hydrology calculate,water conservancy,farmland irrigation management,crop yield estimate,soil moisture prediction and the research of water resource depended on the measure of evaporation quantity. To research for soil evaporation characteristic under water storage pit irrigation condition has greatly significance for perfect water storage pit irrigation and establish the ration and period of irrigation water. In this paper, the technical route is to combine theoretical analyses with laboratory and numerical stimulation. The main results are as follows:(1) Through the experiment of soil column in lab, the results: In the experiment the transformation of soil moisture from high to low during the evaporation course, The transformation of soil moisture from high to low with the distance increase form surface; the soil accumulative evaporation capacity dwindled away with the increment of the bulk density of soil; the relation of average soil evaporation intensity and surface layer soil moisture is beeline function.(2) Through the experimental study of soil evaporation under water storage pit irrigation condition, the results: In the experiment the transformation of soil moisture from high to low during the evaporation course, The transformation of soil moisture from high to low then to high with the distance increase form surface. The transformation of soil moisture is sharp near the surface(0～5cm), the transformation of soil moisture is slender when the distance from surface below 5 centimeter, the transformation of soil moisture gradually enhance when the distance from surface below 35 centimeter; under the same levels of wetting front in soil profile and different light intensity, the decrease of soil accumulation evaporation along with the decrease of light intensity and their relation is exponential; under the same light intensity and the different levels of wetting front in soil profile, the increase of soil accumulation evaporation along with the wetting front in soil profile became shallow and their relation is power; the relation of average soil evaporation intensity and surface layer soil moisture is beeline function.(3) The effect to the soil evaporation of different temperature potential gradient under water storage pit irrigation condition is With the increase of distance from the warm end, the temperature potential gradient is gradually reduced. The value of temperature potential gradient approach zero when the distance from the warm end below 25 centimeter. With the increase of the distance from the warm end the effect to the soil evaporation from high to low. (4) Established the mathematic model of soil moisture movement under the evaporation condition, The implicit schemc method is used to solve the numerical stimulation of soil moisture movement under the evaporation condition in this paper. Contrast analysis has been done to the experiment data. The numerical results are satisfied.