INSAR: Land-Surface Subsidence
Subsidence in the greater Houston area has been identified as a contributor to loss of wetlands, increased shoreline erosion and conversion of freshwater marshes to brackish and saline marshes around the Galveston Bay system. Subsidence has resulted from subsurface liquid withdrawal, primarily groundwater, and in some areas measured at more than twelve feet. Conventional methods of measuring areal changes in land-surface elevations are labor intensive, time consuming, and costly. Technological advancements that offer better spatial detail with comparable or increased precision may enhance the ability to monitor and predict subsidence. Remote-sensing techniques such as interferometric synthetic aperture radar (INSAR) may provide a means of producing a synoptic interpolation of land-surface elevation change in a timely and cost effective manner. The greater Houston area, with its subsidence studies program and networks of traditional measuring systems, provides an ideal standard and relevant opportunity to evaluate the INSAR technology for monitoring land subsidence in a humid coastal environment.
Historical Shoreline Change along shorelines of Texas Bays, 1930s to 1982
The objective of this research is to determine the feasibility and suitability of using INSAR techniques to characterize land-surface elevation changes in the Houston area and compare the INSAR results with maps of land-surface elevation changes obtained using conventional methods. This evaluation will include comparing the INSAR results with regional water-level change maps and the results of groundwater and land-surface subsidence modeling studies. If INSAR techniques are validated by this trial, INSAR may be used to detect coastal erosion by tropical storms, classify landcover, chart siltation, and map water temperature, roughness and marine life concentrations which provide useful tools for the planning and implementation of coastal ecosystem research, management and restoration projects.
The maps and data above were provided by the Bureau of Economic Geology at the University of Texas at Austin.