Study On The Movement And Consumption Of SPAC Water In Sandy Artificial Pasture With Shallow Groundwater Table

In this dissertation,the present status and existing problems of water transport mechanisms and its simulation in SPAC system were analyzed firstly.In 2006-2007 years,experiments were conducted in the Irrigation Experiment Station of Institute of Water Resources for Pastoral Areas at Maowusu desert to investigate the soil water movement, root water uptake, sapflow in trunks, evapotranspiration process of areificial pasture with Shallow Water.The main results as follow:(1) The water characteristic curves of soil changed fastly with low suction(<0.1Mpa), volumetric soil water content increased from saturated value to 10%.And at middle suction section, the cures becomes flat, close to straight line. The effectiveness of Soil moisture retentionefor plant, Is not in the level of water content, but because of the suction force.People have the same views about the lower limit effective water, most of them thought that it is 1.5Mpa, but have different views about the upper limit effective water(field moisture capacity), According to the experimental data , the upper limit effective water is 0.01 Mpa in this dissertation.(2) The relationship of Water potential in SPAC. In time domain, daily variation amplitude of soil water potential is relatively small. The daily variation amplitude of leaf water potential and atmosphere water potential are larger. The daily variation amplitude of soil water potential is much larger than the daily variation amplitude of leaf water potential and atmosphere water potential., the difference among them are 1～3 orders of magnitude at least.In SPACe, atmosphere water potential is much larger than leda water potential and soil water potential, just because of the water potential difference, water movement has driving force.(3) Soil water movment, root water uptake, soil evaporation, crop canopy water moment were comprehensive considered in the SPAC water movement model of Mu Us Sandy Land Artificial Pasture. We can use this model to simulate the temporal and spatial variation of Mu Us Sandy Land Artificial Pasture soil water; analysis the evapotranspiration law of Alfalfa; analysis the impact of groundwater table variation on Alfalfa growth condition, get the ideal groundwater table for Alfalfa gorwth.