Threat of land subsidence to the groundwater supply capacity of a multi-layer aquifer system

Abstract

Study region: The study area was the Cangzhou area in the central-eastern North China Plain (NCP). Study focus: Compaction of the aquifer system leads to a change in hydraulic parameters, including the storage coefficient and hydraulic conductivity. This further reduces its groundwater storage and supply capacity. This study aimed to evaluate the non-linear variation in hydraulic parameters and feedback to the aquifer system during land subsidence. The aquifer system in Cangzhou has suffered severe land subsidence caused by groundwater overexploitation and was chosen to demonstrate this effect. A one-dimensional non-linear compaction and water drainage model was developed considering the changes in the storage coefficient and hydraulic conductivity. New hydrological insights: Based on the physical characteristics of the Cangzhou aquifer system, a compaction model was applied to establish a quantitative relationship between deep groundwater abstraction, hydraulic parameter change, groundwater storage, and supply capacity change during land subsidence. Results show that the inelastic storage coefficient was reduced by 0.005–0.032 for the deep aquifer system in the subsiding area. This represents a reduction of 220 million m3 of groundwater that can be exploited per meter decline in the confined water level. The permanent loss of groundwater storage capacity is estimated to be 9.41 billion m3. These research results have important reference significance for the scientific evaluation of aquifer water supply capacity change in subsiding regions.

Keywords

• Land subsidence
• Storage coefficient
• Non-linear compaction
• Groundwater supply capacity