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ARS Home » Pacific West Area » Tucson, Arizona » SWRC » Research » Publications at this Location » Publication #83480

Title: DOMINANT PROCESSES CONTROLLING SEDIMENT YIELD AS FUNCTIONS OF WATERSHED SCALE

Author
item Lane, Leonard
item HERMANDEZ, M.

Submitted to: International Congress on Modeling and Simulation Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 9/27/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary: Sediment may be moved within a watershed through several processes, including those processes driven by water. The amount of sediment moved out of the watershed in a given time is the sediment discharge, and is often called sediment yield. Major factors and processes controlling sediment yield from watersheds are described and discussed in the context of spatial scale, or size of watershed area. Area is shown to be an important predictor variable that usually is correlated with sediment yield. Experimental data from a small experimental watershed are used in a case study to illustrate the dominant processes controlling sediment yield. Sediment yield on very small areas is controlled by soil detachment, and as watershed size increases, sediment transport and deposition processes control sediment yield. Sediment yield from larger watersheds is controlled by sediment transport capacity of the channels that drain the watershed. Information presented should help guide the conceptual development of sediment yield models and their mathematical formulation. It should also be useful in design and implementation of spatially distributed verification and validation studies.

Technical Abstract: Major factors and processes controlling sediment yield from watersheds are described and discussed in the context of spatial scale. Sediment yield data from selected watersheds across a range of scales are used to illustrate variations of sediment yield with watershed scale. Area is shown to be an important predictor variable which usually is correlated with sediment yield. Experimental data from a small experimental watershed are used in a case study to illustrate dominant processes controlling sediment yield. The case study summarizes and interprets simulation model studies using experimental field data from measurements distributed across a range of scales. Generalizations of dominance of processes as functions of watershed scale are summarized. The general trend is from soil detachment processes to sediment transport and deposition to sediment transport capacity dominating as watershed scale increases from 10-6 to > 10+2 sq km. Information presented should help guide the conceptual development of sediment yield models and their mathematical formulation. It should also be useful in design and implementation of spatially distributed verification and validation studies.