Insufficiently calibrated forest parameters of the Soil & Water Assessment Tool (SWAT) may introduce uncertainties to water resource projections in forested watersheds. In this study, we improved SWAT forest parameterization and phosphorus cycling representations to better simulate forest ecosystems in the St. Croix River basin, and we further examined how those improvements affected model projections of streamflow, sediment, and nitrogen export under future climate conditions. Simulations with improved forest parameters substantially reduced model estimates of water, sediment, and nitrogen fluxes relative to those based on default parameters. Differences between improved and default projections can be attributed to the enhanced representation of forest water consumption, nutrient uptake, and protection of soil from erosion. Better representation of forest ecosystems in SWAT contributes to constraining uncertainties in water resource projections. Results of this study highlight the importance of improving SWAT forest ecosystem representations in projecting delivery of water, sediment, and nutrients from land to rivers in response to climate change, particularly for watersheds with large areas of forests. Improved forest parameters and the phosphorus weathering algorithms developed in this study are expected to help enhance future applications of SWAT to investigate hydrological and biogeochemical consequences of climate change.
1.Pacific Northwest Natl Lab, Joint Global Change Res Inst, College Pk, MD 20740 USA 2.Univ Maryland, Earth Syst Sci Interdisciplinary Ctr, College Pk, MD 20742 USA 3.Sci Museum Minnesota, St Croix Watershed Res Stn, Marine St Croix, MN USA 4.Pacific Northwest Natl Lab, Earth Syst Anal & Modeling Grp, Atmospher Sci & Global Change Div, Richland, WA USA 5.Iowa State Univ, Dept Geol & Atmospher Sci, Ames, IA USA 6.Ohio State Univ, Sch Environm & Nat Resources, Wooster, OH USA 7.Univ Maryland, Dept Geog Sci, College Pk, MD 20742 USA 8.Beijing Normal Univ, Sch Environm, Beijing, Peoples R China
Recommended Citation:
Yang, Qichun,Zhang, Xuesong,Almendinger, James E.,et al. Improving the SWAT forest module for enhancing water resource projections: A case study in the St. Croix River basin[J]. HYDROLOGICAL PROCESSES,2019-01-01,33(5):864-875