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

In order to understand the exploitation yield formation in the North China Plain with problems of intensive over exploitation, a study is conducted using the field data collected from borehole geophysical logs with deep groundwater depression cone bcated in the Dezhou region.The data collection includes groundwater sampling and dynamic monitoring, as well as land subsidencemonibring in the region.Both elastic release ofwater from sandymaterials and water released through aquifer compression in the confined aquifer are calculated for both rate and intensity in different soil layers and partition ones, together with latter flow and aquifer recharge due to ground water exploitation.Results show both elastic release ofwater and water released through aquifer compression are inconstant due to the intensive overeaploitation effect on confined aquifers, which increase with the drop of deep groundwater levels.The longer the intensive over exploitation 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 ofwater 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 sub sidence in the region.