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A Landscape Approach for Evaluationg Change in a Semi-Arid Environment and a Subsequent Analysis of the Hydrological Consequences

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Abstract:Vegetation change in the American West has been a subject of concern throughout the past century. Although many of the changes have been recorded qualitatively through the use of comparative photography and historical reports, little quantitative information has been available on the regional or watershed scale. During the past two decades, important advances in the integration of remote imagery, computer processing, and spatial analysis technologies have been used to better understand the distribution of natural communities and ecosystems, and the ecological processes that affect these patterns. These technologies provide the basis for developing landscape measurements that can be integrated within hydrologic models to determine long-term change and make predictive inferences about the future. This case study employs a system of land cover maps generated from a multi-date satellite imagery database which incorporates Landsat Multi-Spectral Scanner (MSS) imagery from the early 1970s, mid 1980s, and early 1990s and Landsat Thematic Mapper (TM) imagery from 1997. It has been tested over the Upper San Pedro Watershed (U.S./Mexico) where results indicate that extensive, highly connected grassland and desertscrub areas are the most vulnerable ecosystems to fragmentation and actual loss due to encroachment of xerophytic mesquite woodland and urbanization. Changes in surface vegetation have important impact for the hydrology of the region, since the energy and water balance characteristics for these cover types are significantly different. Landscape change was examined relative to its impact on surface water conditions, e.g. sediment yield and surface runoff. Changes in hydrological outputs were estimated for the period of 1973-1997 using hydrological process models and land cover derived from Landsat satellite platforms.
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Citation:Kepner, W. G., D. J. Semmens, C. J. Watts, D. C. Goodrich, and D. A. Mouat. A Landscape Approach for Evaluationg Change in a Semi-Arid Environment and a Subsequent Analysis of the Hydrological Consequences. Presented at International Conference "60 Years of Remote Sensing of Natural Resources: Milestones and Perspectives", St. Petersburg, Russia, June 1-5, 2004.
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Contact: Chris Siebert - (702) 798-2234 or siebert.christopher@epa.gov
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Division: Environmental Sciences Division
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Branch: Landscape Ecology Branch
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Product Type: Abstrct/Oral
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Presented: 06/01/2004
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Related Entries:
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Bullet Item Development of Landscape Indicators for Use in Regional Ecological Risk Assessments
spacer Relationship Reason:   A Project of the Product
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