Studying the Impact of Land Use/Cover Changes on the Water Quality of Weeks Bay, AL: Model vs. Regression

This study focuses on Weeks Bay, a small sub-estuary of the Mobile Bay and one of only three designated Outstanding National Resource Waters in the state of Alabama. We assess the impact of LULC changes in its watershed through watershed modeling and regression equations. The watershed model is calibrated using USGS flow measurements on the main river. Water quality data collected between 1992 and 1996 is used in developing regression equations between TSS, NO₃, P and various LULC types. The 1992 NLCD has been used and assumed to represent the LULC conditions of the period from 1992 to 1996. Comparison of model simulations with observed data for the period [1990–2003] showed that urbanization caused increase in streamflows. The 2002 NLCD has been fed into Regression model and TSS, NO3, and TP concentrations are estimated. The similarities and differences in predictions with each method are investigated.