Economic effects of land subsidence due to excessive groundwater withdrawal in the Texas Gulf Coast area
The Texas Gulf Coast area is experiencing subsidence of the land surface due to excessive withdrawals of groundwater. Damages and property losses are significant, especially along the upper Galveston Bay area, including Houston, Baytown, Clear Lake City and other developments. The study estimates total annual damages and losses for a 945 square mile study area to be $31.7 million. Temporary flooding, permanent inundation, bulkheading and landfilling were the major subsidence-related causes of cost and/or losses in property value. Structural damages from subsidence aggrevated faults were also significant. Damages and losses were more intensive in areas adjacent to Galveston Bay and major waterways. Breakeven analysis implies economic justification for withdrawing only that quantity of water that would result in no subsidence. Water needs above that rate should be imported to minimize total costs to the area. Importation of up to 198 billion gallons per year would be justified to meet demand and avoid subsidence. At current water use rates and prices of surface and groundwater, the area could save as much as $11.4 million annually, even if all water needs were met from surface sources.