沟(河)水利用对宁夏惠农渠灌区水均衡影响的模拟分析

近年来宁夏惠农渠引水量减小,灌溉缺口增大,从排水沟道和黄河提水补充灌溉成为多水源利用的重要模式,但目前对沟(河)水利用对灌区水均衡影响的认识并不清晰。本文利用平原绿洲散耗型水文模型对惠农渠灌区2007—2011年水均衡进行模拟,分析了沟(河)水利用对水均衡的影响。研究区水平衡受引黄河水、降水、沟(河)水和地下水等多种水源的影响,在以水稻为主的上游地区和引水相对困难的下游地区,沟(河)水占灌溉地总补给水量的比例超过30%。以位于上游的第二管理所和位于下游的第七管理所为例,如不利用沟(河)水灌溉,模拟得到的两个分区作物蒸散发量分别减少12.6%和7.7%,且主要发生在6—8月。对于利用50%现状沟(河)水和不利用沟(河)水两种情景,模拟得到的2011年第二管理所灌溉地平均地下水埋深分别下降0.25 m和0.54 m,而第七管理所灌溉地平均地下水埋深分别下降0.22 m和0.50 m。沟(河)水利用对于惠农渠灌区作物耗水具有重要作用,也与地下水等其它水源存在相互转化。本研究可以为惠农渠灌区的多水源综合利用和配置提供科学依据。

Analyzing the impact of drainage water reuse on the water balance in Huinong Irrigation District in Ningxia using the runoff-evaporation hydrological model

The water balance of Huinong Irrigation District from 2007 to 2011 was simulated using the run-off-evaporation hydrological model, and the impacts of drainage water reuse were evaluated. The water bal-ance in the study area was influenced by the irrigation water withdrawal from the Yellow River, precipita-tion, drainage water reuse and groundwater exploitation. For the up-and down-streams, the drainage water reuse is more than 30 % of the total inflow into the irrigated area. Taking the sub-regions 2 and 7 as ex-amples, the impact of drainage water reuse on the water balance was analyzed according to the compari-sons with two scenarios with decreased drainage water reuse. The simulated crop evapotranspiration was re-duced by 12.6 % and 7.7 % respectivety under the scenario with no drainage water reuse. The changes mainly happened from June to August. The simulated average groundwater table fell by 0.27 m and 0.54 m for sub-region 2,and 0.22 m and 0.50 m for sub-region 7,under the scenario with 50 % of current drain-age water reuse and the scenario with no drainage water reuse, respectively. The study indicates that the drainage water reuse has important impact on the water balance in Huinong Irrigation District.