Investigating the Relationship Between Land Subsidence and Groundwater Depletion in the North China Plain Using GRACE and ICESat
The North China Plain (NCP), which encompasses the Hebei, Tianjin, and Beijing provinces, is known as the breadbasket of China and the country’s largest producer of wheat and maize. The NCP relies heavily on groundwater for agriculture, with 60% of its water supply relying on this resource. Such overreliance can result in groundwater depletion and water scarcity, as has been observed in many cases around the world. Land subsidence is often considered as a consequence of groundwater depletion, which has not been quantitatively confirmed, though such aquifer compaction can lead to public safety issues and water management problems by decreasing the holding capacity of important aquifers. In this study, we employed the commonly used Gravity Recovery and Climate Experiment (GRACE) data with well records to validate the groundwater depletion that has already been reported in the NCP, and found similar rates of -2.03 cm/yr water loss for 2002-2014. To quantify the effects of land subsidence, we used NASA’s Ice, Cloud, and land Elevation (ICESat) satellite to measure changes in land elevation in the NCP (5-8 cm/yr). The spatial patterns of groundwater depletion and land subsidence measured from the datasets do not exhibit a one-to-one match, which is to be expected for such processes, but both show the low-lying plains of north China to be a significant area of depletion/subsidence. The seasonality observed from the ICESat data is shown to be sensitive to vegetation height change during the growing season, and interpolated points showed increase subsidence in areas of winter wheat cropland. As confirmed by previous studies, the southern areas of Hebei province are experiencing the most significant groundwater depletion, land subsidence, and contain the most productive cropland, which is of concern to water management in the area and the future of agriculture for northern China.