Comparative study on land subsidence monitoring and control in the Shandong Plain, China and the Greater Houston Area, USA

Both the Shandong Plain in China and the Greater Houston Area in the United States have land subsidence problems that were caused by excessive groundwater pumping. Houston has accumulated more than 100 years of monitoring results and more than 50 years of prevention and control experience, which has certain similarities with the ground subsidence monitoring and control experience of Shandong Plain area in the past 30 years. To further promote and strengthen land subsidence monitoring and prevention, groundwater resource management, digital empowerment, and data sharing in Shandong Province, in this article a comparative study was conducted on the causes of land subsidence, monitoring techniques, groundwater management, and land subsidence prevention and control in the Shandong Plain and the Greater Houston Area. The results indicate that excessive extraction of groundwater is the main cause of land subsidence, and land subsidence management measures based on limiting groundwater extraction have been taken. Currently, the area and rate of subsidence are decreasing in both places. The monitoring methods and techniques used in two places are basically the same, mainly using precision leveling surveying, bench mark fixed on different stratum or borehole extensometers, Global Navigation Satellite Systems (GNSS), and Interferometric Synthetic Aperture Radar (InSAR) techniques, and the density and frequency of observations are gradually increasing. Meanwhile, the management and sharing of observation data is different. The land subsidence management administration agencies in the Houston area are mainly responsible for the collection and sharing of observation data, and do not undertake data processing and research tasks. All observation data are open to the public, and scientific researches based on observation data is mainly undertaken by the U.S. Geological Survey (USGS) and universities. Research results are published on USGS reports or journal articles. Differently, land subsidence and groundwater level monitoring in Shandong Plain are undertaken by the Ministry of Natural Resources and the Ministry of Water Resources, and its affiliated institutions are responsible for field observation, data storage, data analysis and research, as well as formulating regulations for groundwater management. There are certain difficulties in data sharing and integration between departments, which limits in-depth and systematic research on land subsidence.