Vadose Zone Of Moisture Migration In Numerical Analysis

The thesis rely on the state' s keystone item- experimental study on precipitation infiltration recharge intensity and evaporation intensity of water table in Erdos Basin in Cretaceous which is assumed by environmental science and engineering institute of Chang' an university. According to the generally demand of item, the thesis mainly research moisture migration character of wet layer and dry layer which play an important role in studying on precipitation infiltration recharge intensity and evaporation intensity of water table in Erdos Basin. The context as following:Onerbased on the analysis and generalization of the eastern one area' s lithology of field test site, , mainly studying on the effect of wet layer (relative dense layer)which was acted by precipitation feature and dryness degree of experimental field, on precipitation infiltration and evaporation of water table(average depth of years is about 6.8 meter ) by numerical simulation.Two:According to the aerated zone' s lithology of the Erdos basin, research response character of water table (assumption at 10 meter) based on precipitation feature and dryness degree of experimental field by numerical stimulation and probe into condition of come into being dry layer.The auther think that aerated zone' s variability and configuration of physical parameters and estate varible is the bottleneck problem to deep research moisture migration though consulting abundance literatue and viewing moisture migration of aerated zone' s history and actuality from north to south, but resolve this problem still need some time because thereare some concrete problems not only theory but also practice not resolved. Right anylysis and organization weather information is the necessary condition to research infiltration recharge intensity and evaporation intensity of water table by numerical anylysis .The author analyzed available weather information completely by, variability analysis and concluded that variability of infiltration intensity .evaporation intensity and no infiltration days is belong to midding trend to weak. According to this, the author put forward linearity difference of median years of different frequency to improve the precision of using weather information.In order to research response character of aerated zone to infiltration and evoparation, I choice two kind of compute projects:the first'.Original state section of eastern one area was estabilished by item teams of precipitation infiltration recharge intensity and evaporation intensity of water table in Erdos Basin, the secondly:typical section. Two projects adapted hydrus-lD software which is prublished by international ground water modelling center and consulted aerated zone lithology parameter of America agriculture departemen, by fully make use of 20 years' s weather information of Wu sheng qi climate station.The result of numerical analysis of the experimental field indicate that:the wet layer of the experimental field is a double roles sword to water table, either limit the recharge to water table by precipitation infiltration or protect water resource no consumption by evaporation, when a wet layer is exited, the marginal evaporation depth is no more than two meters, below two meters is dry layer and the water content is near residual water content. A wet layer plays an important role in self-restraint of ecological environment up wet layer.The character of wet layer can beexplained by bottleneck effect.In order to better known respond character of precipitation and evaporation of other lithology, the context choice five kinds of lithologies from silt to sand, namely silt, silt loam, loam, sandy loam and sand, the result of numerical simulation show that water table will receive some recharge under the condition that a singleness lithology which saturated hydraulic conductivity is less than 0. 157m/d and depth is no more than 7-8 meters and there is a margin evaporation depth which is no more than two meters. Water content near to residual water content below a marginal evaporation depth which is regard as dry layer. For a sake of saturated zone has strong moisture migration capacity, a singleness lithology which saturated hydraulic conductivity is more than 0.157m/d don' t exit marginal evaporation depth from a angle of water equilibrium.