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The Use of Scenario Analysis to Assess Water Ecosystem Services in Response to Future Land Use Change in the Willamette River Basin, Oregon
Citation:
Hernandez, M., W. G. KEPNER, D. G. Goodrich, AND D. J. Semmens. The Use of Scenario Analysis to Assess Water Ecosystem Services in Response to Future Land Use Change in the Willamette River Basin, Oregon. Chapter 5, P. Liotta, W. Kepner, J. Lancaster and D. Mouat (ed.), Achieving Environmental Security: Ecosystem Services and Human Welfare. IOS Press, Amsterdam, Netherlands, 69:265-268, (2010).
Impact/Purpose:
Sustainable societies are dependent on the goods and services provided by ecosystems, including clean air and water, productive soils, and the production of food and fiber (MEA, 2005). Ecosystem services have been defined as basic outputs of ecological function or processes that directly or indirectly contribute to human health and wellbeing (including economic prosperity). The United Nations initiated the Millennium Ecosystem Assessment to assess the consequences of ecosystem change to human well-being and provide the scientific basis for action needed to enhance the conservation and sustainable use of those systems. Their findings provided a state-of-the-art appraisal of the condition and trends in the world’s ecosystems and the services they provide, as well as the call for action to conserve and use them sustainably. It is the provision of these basic services and their probability for continuation that serve as core ingredients to the concept of human and environmental sustainability. The dilemma that stands before us is to recognize and anticipate change in ecosystem services, in all of its forms, and to understand the impacts to human society before they reach levels of imminent threat.
Description:
Human pressures on the natural resources of the United States have resulted in many unintended changes in our ecosystems, e.g., loss of biodiversity, habitat degradation, increases in the number of endangered species, and increases in contamination and water pollution. Environmental managers are concerned about broad-scale changes in land use and landscape pattern and their cumulative impact on hydrologic and ecological processes that affect stream conditions. The type of land use and land cover has direct consequences for most ecosystem services, including water quantity and water quality, erosion control, and biodiversity. As human pressure continues to increase, ecosystem services worldwide are projected to suffer continued loss and degradation, thus reducing the capacity of ecosystems to provide essential goods and services that contribute to human well-being (MEA 2005). 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. 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 a moderately large river basin in the Pacific Northwest (USA). A process-based hydrologic watershed model was used to examine the contribution of land use/land cover to sediment yield, and nitrate and phosphorous loadings, and identify subwatersheds within the Willamette River basin that would be most affected in the year 2050 relative to three possible future scenarios which include inherent differences related to conservation, existing planning trends, and open development. Thus, the objective of this study was to evaluate the effects of alternative future scenarios that describe varying degrees of urban development and human use on hydrological response related to water quality. Results of this study suggest that the amount of forest along streams and agriculture consistently explained a high percentage of variation in nutrients. The AGWA-SWAT model was used to simulate change in sediment yield, nitrate and phosphorus transported with surface runoff for the three future scenarios. With regard to nitrate, the greatest increase was associated with subwatersheds with agricultural land use and urban areas. Although the model predicted some improvement in basin headwaters for all scenarios, nitrate loadings are expected to decrease under the conservation scenario. The largest decrease was observed in the Coast Range. With regard to phosphorous loadings, the lowest reduction was observed in subwatersheds draining predominantly forest areas. The greatest increase was observed under the open development scenario in subwatersheds with agricultural land use. Urbanization and agriculture are presumed to be the major environmental stressors affecting watershed condition of the Willamette River Basin.
URLs/Downloads:
KEPNER 10-005 FINAL BOOK CHAPTER..PDF (PDF, NA pp, 1752 KB, about PDF)www.iospress.nl
