Simulation Study, Based On The Swap Model Of Water Dynamics Of Farmland

Based on data of soil moisture in field experiments of the water irrigation which have been conducted in the Luancheng Agriculture Experimental Station of CAS, SWAP(Soil-Water-Atmosphere-Plant) Model developed by Wageningen Agricultural College was used as an analysis tool. The parameters in the model were calibrated with the data of irrigation experiment. It is of a great significance to know field evapotranspiration and establish reasonable irrigation scheduling and improve ecological environment. The main researchresults are summarized as following:(1) Analyzed measured soil moisture.The 0-2m soil profiles could be divided into threechanges layer, there were quickly changing layer(0-40cm), slow changing layer(40-120cm) and transition layer(120-200cm).(2) The parameters in the SWAP were calibrated with the data of irrigation experiment The calibrated model represented preferably the field soil water movement.(3) The result calculated By SWAP shows irrigation is key on field evapotranspiration in winter wheat period. How much and what time irrigate water decided evapotranspiration of winter wheat. To summer maize, enough rainfall suffice plant requirement to water. evapotranspiration of each experiment field is similar.(4) The result show that the great irrigation and high rainfall is the major factor to cause deep seepage in this region. But hydraulic conductivity of bottom layer in experiment field is low. So gross seepage is little.(5) The simulated result show that 0-2m soil layer water change is negative.in winter wheat period, soil saving-water minish. Average is -87.6mm .In summer maize 0-2m soil water change is positive. soil saving-water increase greatly. Average is 77.6mm. In a crop rotation year, the 0-2m soil moisture basically achieves balance.