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United States Department of Agriculture

Agricultural Research Service

Title: Modeling Small Semiarid Watersheds in Support of Expert System Development 1268

Authors
item NICHOLS, MARY
item Lane, Leonard

Submitted to: Multiple Objective Decision Support Systems for Land, Water, and Environment
Publication Type: Proceedings
Publication Acceptance Date: August 1, 1999
Publication Date: August 1, 1999

Interpretive Summary: A Prototype Rangeland Health Expert System is being developed at the USDA- ARS Southwest Watershed Research Center. The system is designed to assist users in evaluating the health of rangeland watersheds with respect to soil and site stability. Currently the system is applicable at the hillslope scale, however, the framework exists to extend the spatial scale of application to small watersheds. The small watershed scale system will include mathematical models that simulate the hydrology and erosion within the watersheds. This paper describes the establishment of a semiarid hydrologic model (TLOSS) coupled with a sediment transport model (APOINT) as viable models for inclusion in an expert system. The TLOSS and APOINT models were calibrated and validated at small semi-arid watersheds within the USDA-ARS Walnut Gulch Experimental Watershed near Tombstone, Arizona. Within the framework of an expert system, model output indicating zones of erosion, transport, and deposition within the watershed can be interpreted as an indication of the health of rangeland watersheds with respect to the soil/site stability component of the assessment.

Technical Abstract: A Prototype Rangeland Health Expert System is being developed at the USDA- ARS Southwest Watershed Research Center. Currently the system is applicable at the hillslope scale; however, the framework exists to extend the spatial scale of application to small watersheds. Extending the scale of application will be based on small watershed scale hydrologic and erosion models. This paper describes the establishment of a semiarid hydrologic model (TLOSS) coupled with a sediment transport model (APOINT) as viable models for inclusion in an expert system to assess the soil stability/watershed function components of rangeland health. The TLOSS and APOINT models were calibrated and validated at small semi-arid watersheds within the USDA-ARS Walnut Gulch Experimental Watershed near Tombstone, Arizona. The TLOSS model explained from 74 - 97 percent of the variation in observed runoff volume and from 39 to 73 percent of the variation in peak discharge rate. The results of calibrating APOINT indicated that the model is able to explain from about 85 - 98 percent of the variation in observed sediment discharge from the experimental watershed. Within the framework of an expert system, model output indicating zones of erosion, transport, and deposition within the watershed can be interpreted as an indication of the health of rangeland watersheds with respect to the soil/site stability component of the assessment.

Last Modified: 7/28/2014
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