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AN EVALUATION OF HYDROLOGIC RESPONSE TO 25 YEARS OF LANDSCAPE CHANGE IN A SEMI-ARID WATERSHED
Citation:
Kepner, W G., S. Miller, M. Hernandez, R. Miller, D. C. Goodrich, C M. Edmonds, AND P. Miller. AN EVALUATION OF HYDROLOGIC RESPONSE TO 25 YEARS OF LANDSCAPE CHANGE IN A SEMI-ARID WATERSHED. Presented at 16th Annual Symposium of the U.S. Chapter of International Association of Landscape Ecology, Tempe, AZ, April 25-29, 2001.
Impact/Purpose:
The primary objectives of this research are to:
Develop methodologies so that landscape indicator values generated from different sensors on different dates (but in the same areas) are comparable; differences in metric values result from landscape changes and not differences in the sensors;
Quantify relationships between landscape metrics generated from wall-to-wall spatial data and (1) specific parameters related to water resource conditions in different environmental settings across the US, including but not limited to nutrients, sediment, and benthic communities, and (2) multi-species habitat suitability;
Develop and validate multivariate models based on quantification studies;
Develop GIS/model assessment protocols and tools to characterize risk of nutrient and sediment TMDL exceedence;
Complete an initial draft (potentially web based) of a national landscape condition assessment.
This research directly supports long-term goals established in ORDs multiyear plans related to GPRA Goal 2 (Water) and GPRA Goal 4 (Healthy Communities and Ecosystems), although funding for this task comes from Goal 4. Relative to the GRPA Goal 2 multiyear plan, this research is intended to "provide tools to assess and diagnose impairment in aquatic systems and the sources of associated stressors." Relative to the Goal 4 Multiyear Plan this research is intended to (1) provide states and tribes with an ability to assess the condition of waterbodies in a scientifically defensible and representative way, while allowing for aggregation and assessment of trends at multiple scales, (2) assist Federal, State and Local managers in diagnosing the probable cause and forecasting future conditions in a scientifically defensible manner to protect and restore ecosystems, and (3) provide Federal, State and Local managers with a scientifically defensible way to assess current and future ecological conditions, and probable causes of impairments, and a way to evaluate alternative future management scenarios.
Description:
The assessment of land use and land cover is an extremely important activity for contemporary land management. A large body of current literature suggests that human land-use practices are the most important factor influencing natural resource management at multiple scales. During the past two decades important advances in the integration of remote imagery, computer processing, and spatial analysis technologies have allowed the examination of environmental change. Recently, changes have been documented over a period of approximately 25 years in a semi-arid watershed using a series of remotely sensed images. Landscape change analysis has been linked with distributed hydrologic models to evaluate consequences of land cover change to hydrologic response. A landscape assessment tool using a geographic information system (GIS) has been developed that automates the parameterization of the Soil Water Assessment Tool (SWAT) hydrologic model. This tool was used to prepare parameter input files for the San Pedro Basin, a watershed originating in Sonora, Mexico and flowing into southeast Arizona which has undergone significant land cover change. Runoff and sediment yield were simulated using this model. Simulation results for the San Pedro indicate that increasing urban and agricultural areas and the correlative decline of grasslands resulted in increased annual runoff volumes, flashier flood response, and decreased water quality due to sediment loading. These results demonstrate the usefulness of integrating landscape change analysis and distributed hydrologic models through the use of GIS for assessing watershed condition and the relative impacts of land cover transitions on hydrologic response.