农业节水措施对地下水涵养的作用及其敏感性分析

以北京市大兴区为研究区,利用经校验的水平衡模型,通过调整灌溉满足率和灌溉水利用系数,探讨了不同农业节水措施对增加地下水补给量和减少地下水开采量的作用及其敏感性。结果表明,不同水文年型下,降低灌溉满足率及提高灌溉水利用系数都能减少地下水开采量,且降低灌溉满足率对减少地下净开采量的作用更为显著,有利于区域地下水涵养。在参数取值范围内,地下水净开采量对灌溉满足率的敏感性较大,而地下水补给量对灌溉水利用系数的敏感性较高。与提高灌溉水利用系数相比,对资源性缺水区域,采用先进节水技术,适度降低区域灌溉满足率,对促进水资源持续有效利用及加大地下水涵养具有更显著的效果。

Effect of Agricultural Water-saving Measures on the Quantity of Groundwater Extraction and Recharge and Its Sensitivity

Daxing distict of Beijing was selected as the study area, the effect of agricultural water-saving measures on the quantity of groundwater extraction and recharge was studied by rejusting irrigation water supply rates and irrigation water supply rates based on the calibrated water balance model. The main results were as follows: when irrigation water supply rates decreased and water use efficiency increased, groundwater extraction was decreased significantly in different hydrological years. When irrigation water supply rates decreased, the net groundwater extraction was decreased much more than when irrigation water use efficiency increased. The sensitivity analysis showed that irrigation water supply rate is much more sensitive variable to the groundwater extraction. On the other hand, irrigation water use efficiency is much more sensitive to groundwater recharge. Within the value of index level selection, the variation of irrigation water supply rate is much more sensitive to groundwater extraction and exchange. With the increace of irrigation water use efficiency, the sensitivity to groundwater extraction and exchange is decreased. Therefore, compared with the increase of irrigation water use efficiency, the decrease of regional irrigation water supply rates is much better to promote regional water resource continuously and effectively as well as to reduce groundwater extraction for water shortage region under any water-saving condition.