Relation between Land Subsidence and Deep Groundwater Exploitation in Cangzhou City

Due to long-term excessive exploitation of groundwater, serious land subsidence has been caused in Cangzhou City, Hebei Province, China. With GIS spatial analysis method, this paper conducted an analysis of the quantitative relationship between deep groundwater exploitation and the land subsidence in this area. This quantitative relation was analyzed by using data of both long-term and short-term time series. The long-term time series analysis indicates that the land subsidence volume accounts for 57.6% of the amount of deep groundwater exploitation, indirectly showing the proportion of released water from compressibility of the aquifers and the aquitards in deep groundwater exploitation. Some factors such as hysteresis effects of subsidence may be ignored in the short-term time series analysis, thus the calculated ratio becomes significantly large. From perspective of water resources evaluation, the long-term time series analysis is better to analyze the relation between land subsidence and deep groundwater exploitation.