Predicting future, post-fire erosion and sedimentation with watershed models in the western USA

Abstract:

Increased sedimentation following wildland fire can negatively impact water supply and water quality. Understanding how future changes in fire frequency, extent, and location will affect watersheds and the ecosystem services they supply to communities is of great societal importance in the USA and throughout the world. In this work we predict variability in post-fire sediment yield at a watershed scale as a function of future wildfire conditions throughout the western USA through 2050. Our predictions are based on future fire probabilities, climate change scenarios, and differing GIS-based implementations of watershed sediment yield models. We assess the uncertainties of our predictions and compare predictions based on the GEOWEPP (Geo-spatial interface for the Water Erosion Prediction Project) model, the InVEST (Integrated Valuation of Ecosystem Services and Tradeoffs) Sediment Retention model, and the InVEST Sediment Delivery Ratio model. We show that the models can be parameterized in a relatively simple fashion to predict post-fire sediment yield with accuracy at a watershed scale. Predictions indicate that sediment yield from post-fire hillslope erosion may increase dramatically in coming decades as a function of increased wildfire for many watersheds across the western USA.