Relationships Between Landscape Features and Nutrient Concentrations in an Agricultural Watershed in Southwestern Georgia: An Integrated Geographic Information Systems Approach

This study examined the influence of landscape features on stream nutrient concentrations within the Ichawaynochaway Creek watershed in southwestern Georgia. Baseflow concentrations of both dissolved (SRP, NO3, NH4) and total (TN, TP) nutrients were measured at 17 sampling sites monthly for a period of six months (July 2012 to January 2013). A long-term dataset (January 2008 to March 2012) was also analyzed for baseflow/stormflow comparisons of dissolved nutrient concentrations. Relationships among land-use, geology, soils, physiographic features and nutrients were analyzed at both the subwatershed and riparian corridor scales. SRP concentrations were lower and NO3 concentrations higher than reported in previous studies of the region. Due to dry conditions during the sampling period, nutrient input was likely limited to groundwater contributions and land-use effects were minimal. Trends among water quality variables varied between the upper and lower portions of the watershed, suggesting differences in nutrient transport pathways due to spatial variation. INDEX WORDS: Agricultural watershed, Baseflow stormflow comparison, GIS, Landscape water quality relations, Nitrogen, Phosphorus, Ichawaynochaway Creek RELATIONSHIPS BETWEEN LANDSCAPE FEATURES AND NUTRIENT CONCENTRATIONS IN AN AGRICULTURAL WATERSHED IN SOUTHWESTERN GEORGIA: AN INTEGRATED GEOGRAPHIC INFORMATION SYSTEMS APPROACH