基于温度效应的作物系数及蒸散量计算方法

Calculation of crop coefficient and evapotranspiration based on temperature effect

准确估算作物蒸散量对于制定合理的灌溉计划和提高水资源利用效率至关重要。为反映逐日需水量的动态变化,考虑温度对作物生长状态的影响,采用三基点温度(最适温度、上限温度、下限温度)计算作物系数及蒸散量,并对不同时间尺度上计算精度进行评价。利用五道沟水文实验站大型称重式蒸渗仪实验资料及气象资料,建立了全生育期冬小麦和夏玉米蒸散量模型,结果表明:通过温度模拟冬小麦和夏玉米作物系数变化拟合度均较高,相关系数均达0.80以上,平均绝对误差均约为0.10;不同时间尺度(1、3、5 d),蒸散量模型均具有良好的预报能力,冬小麦预测值与实测值相关系数分别为0.95、0.98、0.98,夏玉米为0.90、0.94、0.97。随着时间尺度由1 d升至5 d,冬小麦绝对误差由0.67 mm·d-1降至0.41 mm·d-1,预报准确率(<1 mm·d-1)由73%升至90%,夏玉米绝对误差由0.94 mm·d-1降至0.37 mm·d-1,预报准确率(<1 mm·d-1)由67%升至90%,预报精度提高。

It is of great significance to accurately estimate the crop evapotranspiration,for developing sound irrigation plans and improving water use efficiency. To explore the dynamic change of daily water demand,and temperature effect on crop growth,the three-point temperature(optimal temperature,upper limit temperature,lower limit temperature) were applied to calculate crop coefficient and evapotranspiration. The calculation models of evapotranspiration for winter wheat and summer maize were established based on the data of large-scale weighing lysimeters and weather monitoring station in Wudaogou Hydrological Experimental Station. The results show that crop coefficients of wheat and maize simulated through temperature had a high degree of fitness with the measured data. Both correlation coefficients are greater than 0.80 and both average absolute errors are about 0.10. The evapotranspiration model has reliable forecasting ability on different time scales,of 1 d,3 d and 5 d. The correlation coefficients of wheat are 0.95,0.98,and 0.98,respectively. With the time scale increasing from 1 d to 5 d,the absolute error decreased from 0.67 mm·d-1 to0.41 mm·d-1,the forecast accuracy rate(<1 mm·d-1) increased from 73% to 90%,and the forecast accuracy improved. Simultaneously,maize showed the same law.