Land Subsidence and Groundwater Level Changes in the Dickenson – La Marque Area, Galveston County, Texas During the Past Two Decades



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Subsidence has plagued the greater Houston Galveston area and prompted the creation of the Houston Galveston Subsidence District (HGSD). Subsidence in the cities of Dickenson and La Marque, in Galveston County, Texas, was extremely rapid (several centimeters per year) during the 1960s and 1970s but has declined to a rate of less than 5 mm per year since the 1990s as a result of the groundwater regulations enforced by HGSD. The United States Geological Survey (USGS), HGSD, National Geodetic Survey (NGS), and the University of Houston (UH) have been continuously monitoring land subsidence and groundwater levels in this area since the 1970s. This study investigated the long-period groundwater, extensometer, and GPS datasets and (1) delineated the regional groundwater heads, (2) studied the compaction and inflation of shallow aquifers, (3) studied the interaction of land subsidence and groundwater level changes in both short-term (days to seasonal) and long-term (several years to a decade), and (4) assessed the effectiveness of the groundwater regulations in the study area. According to this study, the ongoing subsidence rate derived from GPS observations in the area is below 5 mm per year. The regional preconsolidation heads of the Chicot and Evangeline aquifers are approximately at 30 meters below the land surface. The results of this study provide essential information for future urban development, utilization of groundwater resources, and the minimization of urban geological hazards, and guidelines for slowing and finally ceasing the ongoing moderate (a few millimeters per year) to rapid (a few centimeters per year) subsidence that is occurring in the western and northern parts of the Houston metropolitan region.



GPS, Subsidence, Houston, Texas, Groundwater, HoustonNet, Compaction, Aquifer Deformation, Geology