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Stakeholder-informed scenarios to investigate the impact of land use/land change on nutrients, sediment and runoff in the Shenandoah National Park, Virginia
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  • Ebrahim Ahmadisharaf,
  • Iara Lacher,
  • Craig Fergus,
  • Brian Benham,
  • Karen Kline,
  • Thomas Akre,
  • William McShea
Ebrahim Ahmadisharaf
Virginia Polytechnic Institute and State University

Corresponding Author:eahmadis@vt.edu

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Iara Lacher
Smithsonian Conservation Biology Institute
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Craig Fergus
Smithsonian Conservation Biology Institute
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Brian Benham
Virginia Polytechnic Institute and State University
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Karen Kline
Virginia Polytechnic Institute and State University
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Thomas Akre
Smithsonian Conservation Biology Institute
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William McShea
Smithsonian Conservation Biology Institute
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Abstract

Land use/land cover (LULC) change could adversely affect watershed health by elevating nutrients and sediment levels and intensifying the risk of flooding. In this study, a spatially-explicit LULC change modeling framework was coupled with the Chesapeake Bay Watershed Model (CBWM) to investigate the impact of LULC change on nutrients (total nitrogen and total phosphorous), sediment and runoff volume in the watersheds surrounding Virginia’s Shenandoah National Park, U.S. Four stakeholder-informed scenarios alongside a Recent Trends LULC change scenario were studied. The stakeholder-informed LULC change scenarios, which differed in consideration of future planning and population growth, were developed through several meetings with stakeholders. To develop the Recent Trends, the historical LULC trend from 2001 to 2011 was analyzed. Using 2011 as a baseline scenario, the spatio-temporal patterns of LULC change were estimated as influenced by physiographic and socio-economic drivers 50 years in the future (2061). The projected LULCs were fed into the CBWM to predict the change in average annual loading of nutrients, sediment and runoff volume. While the changes in loads at the full study area were not substantial (< 0.9%), changes became more pronounced at finer spatial scales. Expectedly, the LULC change scenario with ad-hoc planning and high population growth resulted in the largest increase in runoff volume. However, the scenario with ad-hoc planning and low population growth showed the largest increase in the simulated pollutants. This was because while this scenario projected less development, it projected more increases in agricultural LULCs that export more nutrients and sediment than other changing LULCs. This implied that sole land use planning based on urban development is not sufficient for watershed protection and agricultural LULCs need to be incorporated in concert in our future planning. This further suggested that land use planning plays a more critical role than population growth rate in water quality management. The results have implications for the Chesapeake Bay total maximum daily load and could help well-informed future land use planning and watershed protection by incorporating the impact of future LULC change on water quality and quantity.