Simulation Of Water Dynamics Using The HYDRUS Model

Soil water refers to the water stored in unsaturated zone, soil water is not only the connection of surface water and groundwater, but also the guarantee of crops, under the background of the increasing contradiction of water resources, that how to ensure the normal growth of corps in the condition of saving water resources is one of the problem should be solved in modern times, so it is particularly important to analyze and study the movement rule of soil water under the condition of natural and human motion. This article was on the basis of the applicability about HYDRUS-1D model in rained area under the condition of corn in the field, and then to analyze soil water movement rule and soil water resources dynamic changes.First of all, the soil water movement mechanism and HYDRUS-1D model principle is analyzed, and optimization back analysis of HYDRUS-1D parameters is carried out based on the data of practical measure. Three indicators, simulation efficiency coefficient, relative error, root mean square error between the measured soil moisture content and simulated soil moisture content, are used to analyze the simulation effect of HYDRUS-1D model, the results show the simulation results agreed with the measures data.Secondly, the simulation results of HYDRUS-1D were used to analyze the movement of soil water, then summarize the law of soil water according to the variation of soil water content and water flux at different soil layer, with infiltration and evaporation, soil water content are fluctuating condition in the whole growth period, and the volatility reduce as the soil layer deepen gradually, at the same time, rainfall infiltration quantity also reduce gradually with the deepening of the soil,; Also analyzed evaporation data in the whole growth period and different reproductive period, from the point of actual transpiration of potential transpiration rate, actual transpiration by 509.3 mm accounted for 86.6% of potential transpiration by 588.17 mm, the effect of water stress is relatively small for corn in the whole growth period.Then, according to the results of the model, the soil water supply situation from rainfall is analyzed emphatically in corn whole growth period, especially on the soil water supply situation in the root affected layer, for the root affected layer the soil water resources recharge amount of 486.17mm, the deep seepage loss of infiltration is 61.34mm. The soil water supply from rainfall mainly distributed within 0-30cm soil layer, only after large rainfall process, rainwater can infiltrate into deep soil, then supply water resources of deep soil layer.Finally, puts forward the soil reservoir and related evaluation indexes(usable capacity, actual capacity, capacity of the empty and so on), discusses the regulation principle and measures of soil reservoir, and some irrigation techniques are raises on rain-fed agriculture.