河网区不同尺度灌区节水潜力分析

Analysis of water-saving potential of different scale irrigation fields in river network districts

针对河网地区回归水的存在及其重复利用加大了节水潜力的尺度效应,也导致了关于真实节水潜力的诸多争论的问题,采用首尾法对比研究了河网区不同尺度灌区灌溉水利用系数,并对不同尺度灌区灌溉水利用系数提高阈值与真实节水潜力进行了综合评价.结果表明,大中型灌区灌溉水利用系数显著低于小型灌区的,且各小型灌区之间的灌溉水利用系数变异系数大.影响灌溉水利用系数的各因素中,节水灌溉因子所占的比重较大,可通过实施节水灌溉工程以提高灌溉水利用系数.大中型灌区单位面积的真实节水潜力显著低于小型灌区的.但同时,由于试验区灌区大中型灌区面积大,节水潜力主要依赖于大中型灌区,特别是大型灌区,试验区各大型样点灌区的近期真实节水潜力为(0.800~6.372)×10~7m^3;远期真实节水潜力为(1.095~8.201)×10~7m^3.不同尺度灌区应采取不同的相应节水措施,以提高灌溉水利用系数.

The existence and reuse of return water in river network districts can intensifies scale effect of water-saving potential,and results in arguments about what the actual water-saving potential is. Irrigation water utilization coefficients of different scale irrigation fields in river network districts are studied by making use of head- tail analysis method. Additionally,the improved threshold of utilization coefficient and actual water-saving potential are evaluated comprehensively. The results show that the utilization coefficients of irrigation water in large- and medium- sized irrigation fields are significantly lower than those of small- sized fields,and the utilization coefficient varies across small- sized irrigation fields obviously. Since the effects of water-saving irrigation factor on utilization coefficient of irrigation water is higher than the other factors,the utilization coefficient of irrigation water should be im-proved by implementing water-saving irrigation projects. The actual water-saving potential per unit area in large- and medium- sized irrigation fields is considerably lower than that of small sized irrigation areas. However,because the area of large- and medium- sized experimental irrigation fields is huge,the water-saving potential mainly depends on those fields,especially in the large- sized irrigation fields which are with 8. 00- 63. 72 million m^3 recent actual water-saving potential and 10. 95- 82. 01 million m^3 forward actual potential,respectively. Therefore,various water-saving measures should be taken for different scale irrigation fields to improve utilization coefficient of irrigation water.