深层水漏斗区开采量组成变化特征与机制

Variation characteristics and mechanisms of exploitation yield formation in the region with confined-groundwater depression cone

为阐明强烈开采条件下华北平原深层水的开采水量来源及组成问题,以德州地区深层水漏斗分布区为重点研究区,通过基于大量钻孔资料对含水层组及其粘性土夹层或透镜体的分析和野外地下水采样、动态监测及地面沉降测量资料等分析,采用分层、分区计算方法对漏斗中心至外围的各分区弹性释水量、粘性土压密释水量、侧向流入和越流补给量进行均衡计算。结果表明：在强烈开采条件下,深层水开采量中弹性释水量和压密释水量所占比率不是常量,随着深层水位下降的幅度和深度增大、超采释压持续时间愈长、开采层中粘性土夹层或透镜体愈多,则区内弹性释水和压密释水的强度及累积地面沉降量愈大;愈靠近漏斗中心,弹性和压密释水强度愈大,相同降深下平均单位降深的地面沉降量愈小。在深层水开采量中粘性土压密释水占35.5%-61.9%,与地面沉降密切相关。

In order to understand the exploitation yield formation in the North China Plain with problems of intensive overexploitation,a study is conducted using the field data collected from borehole geophysical logs with deep groundwater depression cone located in the Dezhou region.The data collection includes groundwater sampling and dynamic monitoring,as well as land subsidence monitoring in the region.Both elastic release of water from sandy materials and water released through aquifer compression in the confined aquifer are calculated for both rate and intensity in different soil layers and partition zones,together with latter flow and aquifer recharge due to groundwater exploitation.Results show both elastic release of water and water released through aquifer compression are inconstant due to the intensive overexploitation effect on confined aquifers,which increase with the drop of deep groundwater levels.The longer the intensive overexploitation of groundwater and the closer to the centre of deep groundwater depression cone are,the higher the clay soil component in confined aquifers will be,as well as the greater the elastic release of water and the water released through aquifer compression are.The calculated composition of elastic release of water varies from 14.2% to 17.5%,and the portion of water released through aquifer compression is from 35.5% to 61.9% and closely related to the condition of land subsidence in the region.