漳河灌区灌溉用水量及水分生产率变化分析

根据湖北省漳河灌区长系列灌溉用水量、作物产量及灌溉面积等资料 ,从田间、灌溉系统及整个灌区3个不同尺度分析了漳河灌区历年来灌溉用水量及灌溉水分生产率变化情况。结果表明 ,漳河水库农业灌溉供水从第一阶段的 8.5亿 m3减少到第三阶段的 3.94亿 m3 ,单位面积灌溉供水量从第一阶段的 5 94 6m3 /hm2减少到第三阶段的 30 91 m3 /hm2 ,灌溉水分生产率从第一阶段的 0 .6 5 kg/m3提高到第三阶段的 2 .37kg/m3。相应的在灌溉系统和田间尺度 ,单位面积灌溉供水量及灌溉水分生产率呈现同样变化规律。由于灌溉系统和灌区尺度水的重复利用程度逐渐提高 ,使从田间、灌溉系统到灌区灌溉水分生产率逐渐提高。分析灌溉水利用率及水分生产率提高的原因表明 ,节水灌溉技术的推广应用以及通过各类调蓄设施提高水的重复利用率等占一半 ,农业结构的调整及作物品种改进使粮食单产提高等占另一半。

Changes of Irrigation Water Use and Productivity in Zhanghe Irrigation System

With long-term data of irrigation water use, crop yields and irrigated area in Zhanghe Irrigation System (ZIS), the irrigation water requirement and water productivity (WP) at three different scales (field, irrigation system, and irrigation district) were analyzed. It was shown that total irrigation water use in ZIS decreased from 0.85 billion m 3 in the first period to 0.394 billion m 3 in the third period with irrigated area keeping nearly no change. Irrigation water Application per unit of land decreased from 5946 m 3/hm 2 to 3091 m 3/hm 2, and WP from 0.65 kg/m 3 to 2.37 kg/m 2. On field and irrigation system scales, all numbers changed as the same. WP increased gradually from field scale, irrigation system scale, to district scale, because of the potentials of water reuse increased obviously from field scale to district scale. It can be considered, with comprehensive analysis, that one half of the WP increment was owed to water saving practice, and another half owed to agricultural production condition improvement and raising crop yields.