Sensitivity Analysis of Flow and Transport Properties of Soil Containing High Densities of Nutrients in Texas Watersheds.

The current study deals with sensitivity analysis of flow and transport properties of soil containing high density of nutrients (nitrogen and phosphorus) because of concentrated dairy farming, use of large amount fertilizers in agricultural fields, and underground septic tanks multiple counties/ watersheds in Texas. The excess nutrients that derived from those sources are either directly absorbed by the soil or transported by the surface runoff or infiltration. Using hydrologic and soil property data from several counties across Texas and HYDRUS-1D model this study aims to analyze the sensitivity of soil parameters such as saturated hydraulic conductivity (Ksat) and parameters, α and n, of soil water retention function for nutrient transport in the specific Texas watersheds. The study areas are delineated using BASIN 4.0. Different depths of soil column have been set up according to the groundwater depths data from different counties. Different precipitation patterns, land use, and soil texture are used as the input parameters for the vadose zone model. Results will be presented with suggested practices to reduce nutrient contamination of groundwater.