Water flux estimation in SPAC system of farmland using Hydrus-1d model: A case of Dongcun Farm in Yuncheng City, Shanxi Province
2011, 30 (4):
Studies on the water flux in SPAC system of farmland are vital to improve the utilization efficiency of agricultural water, and alleviate water shortage in China. In this paper, the Dongcun Farm in Yuncheng, Shanxi Province is taken as an example to estimate the water flux for three main crops (summer corn, cotton and winter wheat) using Hydrus-1d model. For the growing season of summer corn, cotton and winter wheat, the model is built based on soil water movement, root water uptake model and evapotranspiration model, in combination of the initial and boundary conditions. The estimation results for water flux are listed as follows. The transpiration of summer corn accounts for 84.7% of the total evapotranspiration in the whole growing season, and 9.5%, 75.6%, 92.6%, 96.7% and 75.1% in June, July, August, September and October (1st-7th), respectively; transpiration of cotton accounts for 71.6% of the total evapotranspiration in the whole growing season, and 13.1%, 49.7%, 79.7%, 84.6%, 87.4% and 21.5% in May, June, July, August, September and October (1st-24th), respectively; and transpiration of winter wheat accounts for 79.1% of the total evapotranspiration in the whole studying season, and 53.0%, 89.2% and 79.7% in March (10th-31st), April and May, respectively. The deep percolation takes up a great part of water consumption, which is 112 mm, 148 mm and 136 mm for summer corn, cotton and winter wheat, respectively. The deep percolation mainly occurs after irrigation or storm, and after irrigation is up to 74.2 mm, 70.8 mm and 90.0 mm in simulation period, respectively, which undermines the efficiency of irrigation water and need to be reduced by measures. The recharge from groundwater by capillary for soil water is influenced by the depth to water table and the soil water content, and the water amount is 149 mm, 128 mm and 65 mm for summer corn, cotton and winter wheat in simulation period.
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