井灌粮区地下水对农业用水变化的响应及分异规律研究

It is utilization of groundwater resources that support the continuous increasing of grain production in well irrigation areas. But with the sharp rapid of grain and vegetables production increasing, groundwater resources were strongly over exploited. So it is significant to study the impact of agricultural irrigation on variation of groundwater table. This study will make Hufu Plain as the main research area. It will first analyze evolution characteristics of shallow groundwater system, find out the dominant factors which induced groundwater table changing. Then it will take research on the interactive relationship among precipitation, quantity of agricultural irrigation and regional groundwater table. Baded on the interactive relationship, it will study the process of groundwater table variation with agricultural groundwater exploitation changing, as well as the mechanism and the models. Next it will identify the mutation nodes of the process. Through studying the reasons that make groundwater table change obviously different from other period, it will reveal the differentiation regularity. Finally, it will establish the three-dimensional numerical model of groundwater flow. Using the model, this study will verify the differentiation regularity and put forwards up the upper agricultural groundwater exploitation. Make clear of this study will be benefit to regional groundwater reasonable use, as well as groundwater conservation in well irrigation areas.

地下水资源的开发利用是支撑井灌粮区农业产量持续增长的必要条件，但随着粮蔬规模的持续扩大，地下水资源被严重超采。因此，研究井灌粮区地下水对农业灌溉用水量变化的响应过程和响应机制对地下水资源的涵养和保护具有重要意义。本次研究以滹滏平原作为研究区，首先分析地下水位异常变化的时段节点以及地下水系统演变的主导驱动因素，判断不同时期农业地下水开采量对区域地下水位变化的影响程度；其次通过地下水位、降水量、农业地下水开采量之间的互动关系研究，分析地下水位对农业地下水开采量变化的响应过程，提出相应的响应机制和响应模式；然后识别响应过程的突变节点，围绕突变节点处地下水系统补给项和排泄项特征，开展地下水位随农业地下水开采量变化规律分异研究；最后建立研究区三维地下水流数值模型，对分异规律进行模拟验证，从而提出农业地下水开采量上限，为井灌粮区充分利用自然降水条件下地下水资源合理开采和涵养模式的研究提供参考依据。

（1）分析了降水特征与农作物需水特征之间的适应性状况，解释了研究区地下水开采的必要性及超采问题严重性。（2）分析了地下水位年际、年内、及月地下水位年际间变化特征及趋势，揭示了地下水系统补给项、排泄项动态变化规律及对地下水位变化影响的主导因素。（3）阐明了地下水系统主要补给项（降水）、地下水系统主要排泄项（开采）以及地下水位之间的互动关系，并研究了降水和开采对地下水影响的分异节点、分异机制及分异程度。（4）研究了农业活动（种植面积及产量）对地下水位的影响，揭示了农业活动驱动地下水位演变的过程及机制，验证了地下水开采是20世纪80年代后决定地下水位演变的关键因子。（5）建立了地下水流模型，对地下水位对开采及降水变化响应规律进行模拟验证。（6）基于地下水位自身演变特征、降水对地下水位影响分异节点及规律、开采对地下水位影响分异节点及规律，划分了地下水位演变阶段及原因，为进一步量化地下水危机程度提供重要支撑。