The use of scenario analysis to assess future landscape change on watershed condition in the pacific northwest (USA)

Abstract

The ability to assess, report, and forecast the life support functions of ecosystems is absolutely critical to our capacity to make informed decisions which will maintain the sustainable nature of our environmental services and secure these resources into the future. Scenario analysis combined with landscape sciences can be used to characterize uncertainties, test possible impacts and evaluate responses, assist strategic planning and policy formulation, and structure current knowledge to scope the range of potential future conditions. In this study, potential impacts from three wide-ranging scenarios in a large regional area in the northwest United States are compared to current conditions (ca. 1990) of the region in terms of a set of processes that are modeled in a geographic information system (GIS). This study presents an integrated approach to identify areas with potential water quality problems as a result of land cover change projected by stakeholders within the basin. Landscape metrics in conjunction with hydrological process models were used to examine the contribution of land use/land cover to water and sediment yield and identify subwatersheds within the Willamette River Basin (Oregon, USA) that would be most affected in the year 2050 relative to three possible future scenarios which include inherent differences related to conservation, planning, and open development. Specifically, this study provides one example of the use of landscape sciences for environmental assessment that examines the impact of both urban and agricultural development in a large river basin. In particular, it attempts to (1) answer questions that relate to future scenarios that describe contrary positions related to urban development, (2) provide information which can be used to assess the potential changes of the landscape relative to human use, and (3) provide options that could be useful for sustainable management of natural resources and thus minimize future hydrologic and environmental impacts.Keywords: Alternative futures analysis; hydrologic modeling; watershed assessment; environmental security; geographic information systems; landscape indicators; landscape characterization; Oregon; Willamette River