AN ASSESSMENT OF SUSPENDED SEDIMENT TRANSPORT INTO WEEKS BAY RESERVE, BALDWIN COUNTY, ALABAMA, USING GEOSPATIAL MODELING AND FIELD SAMPLING METHODS

The health of an estuary is dependent upon the quantity of suspended sediments reaching the estuary through the watershed. Too much sediment can be detrimental to the system by clouding the water, infilling the system, stressing the aquatic life, and bringing non-point pollution into the estuary (Cronin, 1967). Excess sediment is especially problematic within estuaries that are undergoing rapid development, such as within the Weeks Bay Estuary in Alabama. The effect of this urban development on the sediment influx to Weeks Bay, though, has not yet been fully quantified, and the impact of this excess sediment on the estuary is still unknown. This current research examines the relationship between urban development and sedimentation in the Weeks Bay watershed.

Geospatial techniques will be used to identify areas within the Weeks Bay watershed that might have a high potential for excess sedimentation. Changes in landuse from 2001 to 2006 will be determined from Landsat 7 satellite imagery, and areas with an increase greater than 30% in landuse change to urban or a decrease greater than 15% in vegetation (forested and herbaceous) will be identified. The elevation, slope, and stream proximity will be derived from Digital Elevation Models. These topographic variables will be combined with landuse change to determine areas of high, medium, and low sedimentation potential. Field sampling of suspended sediment and stream discharge within the watershed will be compared to the sedimentation potential classes. Preliminary results show a correlative relationship between sedimentation and increase in urban development, yet more research is needed.