华北平原地下水动态及其对不同开采量响应的计算——以河北省栾城县为例

自从20世纪60年代大规模开采地下水以来,栾城县的地下水位以每年大约0.65 m的速度下降.降雨量的减少、农业产量的大幅度提高、种植结构的变化以及上游水利工程的修建,都与地下水位的下降有着密切联系.利用Visual Modflow软件,在分析该县水文地质条件与水资源利用的前提下,运用三维地下水流模型,通过有限差分方法对栾城县的地下水系统进行了模拟,结果表明:5个观测孔的地下水位计算值与实测值拟合程度很好,模拟出的地下水流场与实际情况基本一致.利用掌握的水文地质资料,进行参数分区,通过实测资料的校正、调参,模拟出各分区参数值.利用校正后的数学模型,对栾城县地下水对不同开采量的响应进行了计算,结果如下:在现状农业开采量1.01×108m3基础上分别减少14%(0.14×108m3)、29%(0.29×108m3)和增加29%(0.29×108m3)的情况下,到12月份5个观测孔的平均地下水位分别比现状地下水位上升了0.33 m,0.64 m和下降了0.45 m.

Groundwater Dynamic Drift and Response to Different Exploitation in the North China Plain: A Case Study of Luancheng County, Hebei Province

The groundwater table has been declining at a rate of 0.65 m/yr in Luancheng County since pumping groundwater on a large scale in the 1960s. The decrease of the precipitation, large increase of the agricultural output, variation of the crop growing structure and the building of the hydraulic project in the headwater area all tie up with the decline of the groundwater table. On the basis of analyzing the hydrogeological condition and the water resources utilization of Luancheng County, we build a three-dimensional groundwater flow model, and simulate the groundwater flow through finite-difference method using Visual Modflow software. We divide the research field into four parts after analyzing the hydrogeological condition. After calibrating and adjusting parameters using measured data, we simulate the parameters of hydraulic conductivity and specific yield. Using the calibrated model, this article analyzes the agricultural water saving potentiality and its influence on the groundwater. The results are as follows: (1) if we decrease the pumping water by 0.14×108 m³, the average groundwater table of five observation wells in December will rise by 0.33 m; (2) if we decrease the pumping water by 0.29×108 m³, the average groundwater table of five observation wells in December will rise by 0.64 m; (3) if we increase the pumping water for 0.29×108 m³, the average groundwater table of five observation wells in December will decline by 0.45 m. So we can draw a conclusion that controlling the agricultural water use is an important way to prevent the groundwater table's decline.