Impacts of land use and climate change on hydrologic processes in shallow aquatic ecosystems

Mobile Bay is a significant resource for human uses with important implications on commercial fisheries, coastal development, industry and tourism. Submerged aquatic vegetation (SAV) provides habitat in the littoral zone important to Gulf fisheries. Alabama coastal systems have been increasing in population and this with LCLU change in the surrounding areas of the coast are causing changes in streamflow discharges. The change in river outflow can affect the quality of the water in the bay, which is essential to the health of the ecosystem. Watershed and hydrodynamic modeling has been performed to evaluate the impact of land use and climate change in Mobile and Baldwin counties on the aquatic ecosystem in Mobile Bay. Remote sensing data (Landsat Images) were used as model input for the LCLU scenarios for the years of 1992 and 2001. The Prescott Spatial Growth Model (PSGM) was used to project the 2030 land use scenario based on observed trends. The data provided by Intergovernmental Panel on Climate Change (IPCC) for the South region on future temperature and precipitation projections were used to create future climate scenarios of 2025 and 2050. Results indicate that the LCLU changes are increasing the freshwater flows into the Bay. The projected drier and hotter climate will decrease the freshwater flows into the Bay too. Variations in flow into the Bay can change the sediment loads, salinity and temperature of the water. These changes affect the normal conditions of the habitat, distribution and abundance of particular species of plants and the amount of light that SAVs need for survival.