降水和开采变化对滹滏农业区地下水流场影响特征与机制

Characteristics and Mechanism of Precipitation and Groundwater Exploitation Influence on Groundwater Flow Filed in Agricultural Field Hufu

准确认识地下水流场演变机制是开展地下水系统涵养修复的前提和基础。以滹滏农业区为典型区,基于该区逐月地下水动态观测和降水资料,采用区域地下水动态模型及时间序列趋势分析等方法,开展了降水和开采变化对农业区地下水流场影响特征与机制研究。结果表明:降水变化是驱动地下水位变幅的重要因素,在枯水年份地下水位下降阈值介于0.5~4.0 m,在平水年份下降阈值介于0~2.0 m,在丰水年份地下水位大幅上升;地下水位与开采量关系不明显,但与区域累计超采量有显著的相关关系,地下水累计超采量每增加1.0亿m3正定农业区地下水位下降6.4 m、藁城农业区下降7.3 m。随降水量的增大,农业区开采强度呈幂函数减少趋势,地下水补给量呈幂函数增长趋势。农业开采减少趋势线和地下水补给增加趋势线的交会点为地下水系统平衡点,在平衡点左侧的年份地下水系统处于负均衡状态,离平衡点越远地下水位下降幅度越大;在平衡点右侧的年份地下水系统处于正均衡状态,离平衡点越远地下水位上升幅度越大。研究成果可为区域地下水开发利用提供理论指导。

Accurate understanding the groundwater flow field evolution mechanism is the precondition and foundation for the development of groundwater system conservation and restoration. Hufu agricuhural area as a typical area, based on the monthly dynamic observation data of groundwater and precipitation, the research of characteristics and mechanism of precipitation and groundwater exploitation influence on groundwater flow filed is carried out with the methods of regional groundwater dynamic model and time series trend analysis. The results showed that： the precipitation change is an important factor driving the ground water level, in dry years groundwater level decline between the threshold from 0.5 to 4.0 m, in normal flow year the threshold is in between 0-2.0 m, in wet year a rise of groundwater level; the relationship between groundwater level and amount of groundwater exploitation is not obvious, there is a significant correlation between the accumulated groundwater overexploitation, an increase of 100 million m^3 of accumulated groundwater overexploitation, the groundwater level will decrease 6.4 m in Zhengding agricultural area, and Gaocheng agricultural area decreased by 7.3 m.With the increase of precipitation, the exploitation intensity decrease by exponentially trend, groundwater recharge is increasing power function, the intersection of agricultural exploitation trend line and groundwater supply increase trend line is the equilibrium point of the groundwater system, on the left side of the point, the groundwater system is in negative balance. With the distance from the equilibrium point bigger, the groundwater level decline rate increase. On the right side of the equilibrium point, the groundwater system in a state of positive equilibrium, with the distance from the equilibrium point bigger, the groundwater level incline rate increase. This study can be served as guidance to regional groundwater development and utilization.