Submitted to: American Water Resources Association Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 9/1/2007
Publication Date: 9/20/2007
Citation: Garbrecht, J.D. Water and sediment yield response to multi-year precipitation variations in a central Oklahoma watershed [abstract]. In: Proceedings of the American Water Resources Association Annual Conference, September 12-15, 2007, Albuquerque, New Mexico. 2007 CD-ROM. Interpretive Summary: Abstract Only.
Technical Abstract: Persistent, multi-year departures of annual precipitation from long term mean have been observed in various parts of the United States. The Dust Bowl years in the central plains and the recent drought in the West are examples of such persistent departures. Departures in annual precipitation that last 5 or more years are called wet and dry periods. In central Oklahoma, one wet and three dry periods were identified between 1940 and 2005 and their impacts on the water yield from an 800 km2 agricultural watershed were investigated. The difference in mean annual precipitation between wet and dry periods was about 30% of long-term mean. The corresponding difference in mean annual water yield was about 100% of long-term mean. Thus, small or moderate multi-year variations in precipitation can amplify into comparatively large water yield variations which in turn impacts watershed sediment yield. For the watershed under consideration, the difference in mean annual sediment yield between wet and dry periods was about 180% of long-term mean. Similar trends are likely applicable to soil erosion and movement of agrichemicals since many such substances are adsorbed to soil particles and transported with sediment. The non-linearity and sensitivity of the cause-effect relationships linking precipitation, runoff, and sediment yield, and the presence of multi-year precipitation variations suggest that great care should be taken when selecting a representative climatic record for design and assessment of soil and water conservation measures.