SIMULATIONS OF NUTRIENT FLUXES FROM WILD FIRES USING THE NUTRIENT LOSS MODEL

Wild fires cause significant changes to surface water chemistry, but there are only limited research field data collected at monitoring sites. We are testing a hypothesis that grain size distribution of eroded material, including specific surface area of eroded grains, can be used to approximate fluxes of nutrients transported in streams after wild fires. We built the Nutrient Loss Model (NLM), a Python-based program that uses erosion simulations from WEPPcloud (the web-based Water Erosion Prediction Project model) to predict nutrient fluxes in both particulate and dissolved forms. We discuss correlation between types of soils, land uses, and weather conditions on erosion, and its relation to transported fluxes of nitrogen, phosphorus and carbon. We are testing three different modeling approaches that use surface runoff flow concentration, subsurface runoff flow concentration, and baseflow concentration in mg/L. The second approach adds a non-dimensional “nutrient recalcitrance” ratio, and the third approach adds loss parameters for all sediment grain size categories. We are also comparing the results of WEPP Cloud-based modeling with simulations conducted in GeoWEPP, an ArcGIS Desktop-based model. Both models provide results that differ over a range of soil types and land uses.