Using Geospatial Analysis and Hydrologic Modeling to Estimate Climate Change Impacts on Nitrogen Export: Case Study for a Forest and Pasture Dominated Watershed in North Carolina

Abstract

Many watersheds are currently experiencing streamflow and water quality related problems that are caused by excess nitrogen. Given that weather is a major driver of nitrogen transport through watersheds, the objective of this study was to predict climate change impacts on streamflow and nitrogen export. A forest and pasture dominated watershed in North Carolina Piedmont region was used as the study area. A physically-based Soil and Water Assessment Tool (SWAT) model parameterized using geospatial data layers and spatially downscaled temperature and precipitation estimates from eight different General Circulation Models (GCMs) were used for this study. While temperature change predictions are fairly consistent across the GCMs for the study watershed, there is significant variability in precipitation change predictions across the GCMs, and this leads to uncertainty in the future conditions within the watershed. However, when the downscaled GCM projections were taken as a model ensemble, the results suggest that both high and low emission scenarios would result in an average increase in streamflow of 14.1% and 12.5%, respectively, and a decrease in the inorganic nitrogen export by 12.1% and 8.5%, respectively, by the end of the century. The results also show clear seasonal patterns with streamflow and nitrogen loading both increasing in fall and winter months by 97.8% and 50.8%, respectively, and decreasing by 20.2% and 35.5%, respectively, in spring and summer months by the end of the century.

WOF-SWAT: A Web-Based Open-Source Framework for Investigating the Hydrological Impacts of Climate Change and Human Activities Through Online Simulation and Visualization of SWAT Models

“…Climate change, together with human activities such as deforestation, urban development, and unregulated sewage discharge, are further complicating the prediction of watershed-scale processes by placing additional uncertainty on future water resource conditions. In an attempt to answer the numerous important questions posed by the hydrological community, a large number hydrological models have been devised to simulate the hydrological cycle, investigate cause-effect relationships at various spatial and temporal scales, and help in decision-making to find solutions for better watershed protection and management [1][2][3][4]. However, it is considered that these models have not yet been applied to their full potential in terms of watershed management and policy-making [5,6].…”

“…In this study, we implemented a web-based open-source framework that links with SWAT, named WOF-SWAT (web-based open-source framework for SWAT). WOF-SWAT characterizes on following aspects: (1) it provides an open-source platform that the users can directly use as or extend to comprehensive watershed management tool; and to the best of the authors' knowledge, (2) it is the first web-based watershed management tool for investigating individual and combined impacts of climate change, land use change, and point-source pollutants using SWAT model. We describe and discuss details of the workflow, interfaces, and key processes of the proposed WOF-SWAT framework.…”