Watershed Symposium 2022

Frequent wildfires affect streamflows which influences estimates of water budgets. It is a complex effort to accurately estimate river discharges. So, determining how well National Water Model predicts streamflow in burned areas during peak Spring and late-season low flows will help access required improvements in the model.

Research studies have found that climate change influences wildfires. Wildfires in the western United States alter the landscape and overall hydrological cycle, altering the timing and magnitude of the streamflow response to snowmelt and high intensity precipitation events. The National Water Model (NWM) is a tool to anticipate hydro-meteorological influences on streamflow and fill the gaps between coarse USGS streamflow monitoring locations, providing a decision-making tool to guide the domestic, agricultural, recreation, power generation, and flood control components of water resources management. To assess the NWM v2.1 predictive performance surrounding spring melt and supply-limiting low-flow events in recently burned catchments, we use the Cooperative Institute for Research to Operations for Hydrology (CIROH) Land Use Land Cover (LULC) Streamflow Evaluation tool. We evaluate multiple catchments in the intermountain west, and collocated with USGS monitoring stations, evaluating predictive performances using Kling Gupta Efficiency metric (KGE), coefficient of determination (R2) and Percent Bias (PBIAS). Given the observed prediction errors, determining the accuracy of streamflow predictions of NWM v2.1 in burned catchments provides a benchmark to quantify future model improvements as well as an opportunity to enhance existing predictions with new post-processing methods. As much of the drinking water for the Salt Lake area comes from these fire-vulnerable watersheds, improved modeling will help regional water prediction studies for Utah.