农田水分生产率估算方法及应用

水分生产率是评价农业灌溉用水管理水平和节水效果的一个重要指标.本文利用遥感数据定量估算了流域平原区的蒸散量和干物质量,采用经验的收获指数计算了海河流域2003-2008多年平均水分生产率.通过在水资源三级分区的统计结果分析表明：遥感估算的水分生产率可以反映单方水产出的空间差异，海河流域平原平均水分生产率为0.99kg/m3，变化范围为0.02-2.13kg/m3，总体水平较低，南北差异较大。通过ET,产量和水分生产率关系的分析表明水分生产率与产量线性相关(R＝0.97),提高产量将一直是流域提高水分生产率的重要研究方向。水分生产率与产量随ET变化均为先线性增加后减小的特点,在两季作物区当年耗水量在335-575mm范围变化时,水分是影响产量和水分产出效益的关键因子,要着重提高中低产区域的水分生产率; 当耗水量超过575mm,水分不是唯一的限制因子，以提高作物的收获指数为重点。

Estimation of agricultural water productivity and application

Agricultural water productivity is an important indicator to assess the effect of irrigation water management and water conservation. In this paper, a method to calculate water productivity based on evapotranspiration(ET) and dry matter(DM) estimated by remote sensing data is presented. Water productivity data are calculated and analyzed in the plain of Hai River Basin from 2003 to 2008. The results show that water productivity data estimated by remote sensing can reflect spatial differences in output per cubic meter amount of water. The average water productivity for the plain of Hai River Basin is 0.99kg/m3,the range is 0.22~2.13kg/m3, and the overall level is low with big difference between north and south. The relationship between yield and water productivity shows higher linear correlation (R = 0.97), and increasing yield production remains an important direction to improve the water productivity level in the basin. The curves between water productivity changes with ET and yield changes with ET are similar: keeping stable after the linear increasing trend. When the water consumption of wheat and maize rotation region is between 335 ~ 575mm, the water is main limit factor for yield production. While the water consumption is higer than 575mm, the harvest index is an important limit factor except for available water.