Analysis of Soil-Water Movement by Using HYDRUS-1D In a Maize Field In the Arid Region of China.

One-dimensional analysis of water movement in a maize field in the arid region of China during 2008-2009 was done by using HYDRUS-1D software package. The potential values of evaporation and transpiration from the evapotranspiration calculated by the FAO Penman-Monteith method were separated by the FAO dual crop coefficient method. The evaporation part was assigned as a surface boundary and the transpiration part as an intake term. The hydrostatic pressures measured at a fixed depth in a well at the center of the field were dispensed as the bottom boundary. The simulated soil-water content at 0.1, 0.2 and 0.4 m below the soil surface agreed well with the measured values when the soil profile was divided into three layers: a top silt layer with high hydraulic conductivity, a middle silt layer with low hydraulic conductivity and a bottom sandy loam layer. The two silt layers with different hydraulic conductivity could reveal the truth of crack formation at the surface layer. In addition to soil-water content, the actual evapotranspiration calculated by the HYDRUS-1D was compared with that calculated by Bowen-ratio method. Under the order of ten days’ values, both evapotranspiration values agreed very well during the two years of investigation.