基于温度的作物需水量估算方法

科学准确地估算作物需水量是灌溉预报和农业用水管理的基础，本文探索如何充分利用温度这一定量信息估算作物需水量，并对不同时间尺度的估算精度进行评判分析，以更好地服务于灌区的灌溉预报和水土资源管理.利用新乡市1970—2010年的气象数据对Hargreaves公式的3个基本参数和McClound公式的2个参数进行了订正；针对冬小麦生育期，筛选出Hargreaves公式作为参考作物需水量（ET₀）的估算方法，然后结合基于温度的作物系数计算模型建立了基于温度的作物需水量计算模型，根据2011年10月—2012年5月新乡气象和灌溉试验资料对不同时间尺度（1、3、7 d）的ET_c进行了预测和精度评估.结果表明： 1、3、7 d ET_c的预测值与实测值的相关系数分别达到0.883、0.933、0.959，一致性指数分别达到0.94、0.95、0.97，预测误差随时间尺度增大而减小，误差<1 mm·d^-1的预报准确率均>80%，误差<2 mm·d^-1的预报准确率均>90%，各时间尺度的预报精度都较高，可为灌区灌溉预报和农业用水管理提供较为可靠的数据支撑.

Calculating method for crop water requirement based on air temperature.

The importance of accurately estimating crop water requirement for irrigation forecast and agricultural water management has been widely recognized. Although it has been broadly adopted to determine crop evapotranspiration (ET_c) via meteorological data and crop coefficient, most of the data in whether forecast are qualitative rather than quantitative except air temperature. Therefore, in this study, how to estimate ET_c precisely only using air temperature data in forecast was explored, the accuracy of estimation based on different time scales was also investigated, which was believed to be beneficial to local irrigation forecast as well as optimal management of water and soil resources. Three parameters of Hargreaves equation and two parameters of McClound equation were corrected by using meteorological data of Xinxiang from 1970 to 2010, and Hargreaves equation was selected to calculate reference evapotranspiration (ET₀) during the growth period of winter wheat. A model of calculating crop water requirement was developed to predict ET_c at time scales of 1, 3, and 7 d intervals through combining Hargreaves equation and crop coefficient model based on air temperature. Results showed that the correlation coefficients between measured and predicted values of ET_c reached 0.883 (1 d), 0.933 (3 d), and 0.959 (7 d), respectively. The consistency indexes were 0.94, 0.95 and 0.97, respectively, which showed that forecast error decreased with the increasing time scales. Forecasted accuracy with an error less than 1 mm·d^-1 was more than 80%, and that less than 2 mm·d^-1 was greater than 90%. This study provided sound basis for irrigation forecast and agricultural management in irrigated areas since the forecasted accuracy at each time scale was relatively high.