基于BEPS生态模型模拟农田土壤水分动态

Simulation of soil water content in farm lands with the BEPS ecological model

为了提高农田水分动态的模拟精度,以提高农田水管理的效率,该文研究验证了BEPS机理生态模型模拟季风气候区农田土壤水分的能力,分析了导致模型误差的原因。结果表明,BEPS模型能较好地模拟江苏省徐州农业气象试验站冬小麦生长季根层土壤水分动态,2000-2004年模拟结果与实际观测值的决定系数R2的范围在0.1339～0.9225之间,均方根误差和平均绝对误差分别在0.026113～0.06317和0.0232～0.0525之间。土壤水分饱和传导率和决定土壤水分传导率变化的参数对模拟结果有较大影响。模拟结果的可靠性及其对土壤水分饱和传导率和决定土壤水分传导率变化的参数的敏感性与降水和土壤含水率条件有关,当降水长期偏少、土壤含水率下降时,模拟的上层土壤含水率会较观测数据偏低,对2个参数的敏感性上升。

Soil water content（SWC） is an important factor which affects the growth of crops and also a valuable parameter required for scientific agricultural water management.Therefore,simulation and prediction of SWC are of significance for agriculture.The aim of the paper was to validate the ability of the mechanistic ecosystem model BEPS to simulate SWC of farm lands in areas with a monsoon climate and to investigate the major factors causing uncertainties in simulated SWC.Simulated SWC was compared with measurements in the growing seasons of winter wheat during 2000 to 2004 at Xuzhou agrometeorological station,Jiangsu province.The results showed that BEPS model was in general able to capture the seasonal and interannual variations of SWC,with R2 in the range from 0.1339 to 0.9225,root mean square error and mean absolute error in the range from 0.026113 to 0.06317 and 0.0232 to 0.0525,respectively.Simulated SWC was sensitive to saturated hydraulic conductivity（K） and the parameter b.The reliability and sensitivity of the simulated results depended on the condition of SWC and prepipitation.Simulated SWC was underestimated by the model and its sensitivity to K and b increased during the period with continuously sparse precipitation and low SWC.