Tim Strickland

SWAT Application for Conservation Effects Assessment in the Southeastern Coastal Plain

The Soil Water Assessment Tool (SWAT) was used to examine the impacts of alternate land management practices on water quantity and quality within a Coastal Plain Watershed. Runoff, sediment, and pesticide loadings were examined. SWAT simulations indicate a linear decrease in sediment and pesticide yields will be observed if conservation tillage is implemented on the cotton acreage within this watershed. For sediment, a 20% reduction in loss can be obtained through implementation of conservation tillage on 15% of the watershed area. SWAT simulations indicated that a 45% reduction in the simulated pesticides can be expected when the conservation practices are implemented on the same acreage. However, the model did simulate an increase in water yields from the watershed when these practices were implemented, likely due to increases in infiltration in the uplands. This increase in infiltration and subsequently streamflow could result in greater losses of soluble chemicals, nitrate in particular.

Surface Runoff and Lateral Subsurface Flow as a response to Conservation Tillage and Soil-WaterConditions

Surface runoff and lateral subsurface flow were measured on six 0.2 ha plots in South Georgia in order to quantify the effects of conservation tillage. Significant differences in water losses were observed between the conventionally and strip tilled plots. Surface runoff from the conventionally tilled plots exceeded that from the strip tilled plots while subsurface losses were reversed. Surface runoff losses from the conventionally tilled plots exceeded those from the strip tilled plots by 80%. Subsurface losses from the strip tilled plots exceeded those from the conventionally tilled plots by 67%. Overall, a net annual gain of 60 mm of water was observed for the strip till plots.