Estimating Net Gains and Losses of Coastal Wetlands in Galveston County and Cameron County, TX

Abstract

Coastal wetlands serve many important ecological services. One of these important ecological services is there use as storm buffers. Coastal wetlands provide habitat for migratory birds and aquatic species and can improve water quality. In the late 1990s, the US Fish and Wildlife Services published a study outlining the trends of coastal wetlands from the 1950s to early 1990s. In this thesis, wetland gains and losses are calculated for Galveston County and Cameron County between 2001 and 2011. Maps from the National Land Cover Database were used to determine wetland areas for the years 2001, 2006, and 2011. ArcGIS was used to compare land cover between the study periods to determine overall wetland losses and gains. A statistical analysis was performed between wetland loss and population data to determine if increased population density lead to a higher loss of wetlands. Our analysis indicates that wetlands loss is still occurring; however, at a lower rate of loss (0.14% -0.18% annually) than the USFWS study predicted earlier (2.7%). In addition, the majority of wetland losses were because of conversion to upland areas. We found a positive correlation between increased population density and decreased wetland area; however, the trend was not significant. This present study shows how the majority of wetland loss in Galveston and Cameron County is occurring as a result of increased upland areas. In addition, the study shows that the use of online mapping systems can be used as a low-cost alternative to assess land changes when field tests are not feasible.