运用SWAT模型评估海河平原井灌限采条件下浅层地下水动态与粮食产量变化

Groundwater overdraft due to extensive irrigation has led to a shallow aquifer depletion crisis in the Haihe River basin. The shallow groundwater table in large well-irrigation area in this basin is declining continuously. The piedmont plain of Taihang Mountains in Hebei province, which is located in the Haihe River basin, is a typical shallow groundwater overexploited region. This study would focus on this well-irrigated plain to solve the dilemma between groundwater depletion and crop production demand. A modified Soil and Water Assessment Tool (SWAT) model would be used to conduct simulations under different limited irrigation schemes for winter wheat. By comparing the shallow groundwater dynamics, crop yields, crop water productivities, soil water and groundwater balances under different scenarios, the effects of different limited irrigation schemes would be assessed quantitatively. Considering the trade-off between shallow groundwater conservation and crop production, the optimal irrigation schedule that could minimize winter wheat yield loss under the constraint of stopping groundwater drawdown, and the optimal irrigation schedule that could minimize shallow groundwater depletion under the constraint of restricting crop yield reduction would be explored in each subbasin. The results should provide a quantitative reference for the groundwater management policies aimed at limited irrigation schedule for winter wheat to this well-irrigated plain.

高强度农业灌溉导致海河流域井灌区已经大范围出现浅层地下水位持续下降、含水层储水量持续消耗等生态环境问题。本项目以该流域内典型的浅层地下水超采区——河北省太行山山前平原为研究区，拟应用改进了地下水模块的分布式水文模型SWAT，对冬小麦不同的限水灌溉方案进行模拟研究，对比和分析多种限水灌溉情景下该区域的浅层地下水动态、作物产量和水分生产力的变化及土壤水和地下水的均衡态势，进而评估这些限水灌溉方案对浅层地下水压采与农田节水的效应。并从权衡地下水涵养与粮食生产的角度，分别以浅层地下水位不再继续下降为约束条件、冬小麦减产幅度最小为目标函数和以冬小麦适度减产为约束条件、浅层地下水位下降程度最小为目标函数，优化各子流域在冬小麦生育期不同降水水平下的灌溉方案之组合，获得可供推荐的冬小麦生育期的优化灌溉模式。研究结果将为这个亟需实施地下水压采措施的井灌平原在实施不同的冬小麦限水灌溉方案时提供决策依据。