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United States Department of Agriculture

Agricultural Research Service

Title: Streamflow Response of a Southern Plains Watershed to Decade-Scale Precipitation Variation

Authors
item GARBRECHT, JURGEN
item Van Liew, Michael

Submitted to: Environmental and Water Resources Institute World Congress Proceedings
Publication Type: Proceedings
Publication Acceptance Date: March 1, 2001
Publication Date: March 1, 2001

Interpretive Summary: Decade-long variations in precipitation can have a profound impact on agricultural production and surface water supply for urban and industrial use. In this study, changes in the amount of water leaving a watershed as a result of decade-long variations in precipitation was investigated for the Little Washita River Experimental Watershed (LWREW) in nsouthwestern Oklahoma. Understanding these changes is critical for long- term strategic planning of adequate water supplies to meet the demands of a growing society. This study showed that the amount of water leaving the LWREW was highly sensitive to decade-long changes in annual precipitation. A 10 percent increase/decrease in decade-long precipitation lead to a 40 to 60 percent increase/ decrease in the amount of water leaving the watershed. This high sensitivity suggests the need to consider decade-long variations in precipitation in the planning of water resources infrastructure and development of long-term management strategies for efficient storage and utilization of surface water resources. In addition, it was qualitatively inferred that soil water for plant growth at watershed scales was not very sensitive to decade-long variations in precipitation. This aspect is currently subject to more detailed investigation.

Technical Abstract: The sensitivity of streamflow response to decade-long variations in precipitation was investigated for the Little Washita River Experimental Watershed (LWREW) in southwestern Oklahoma. Understanding the dynamics of this precipitation - streamflow interplay is important for long-term strategic planning of adequate water supplies to meet the demands of a growing society. This study showed that trends in annual streamflow leaving the LWREW are sensitive to trends in average annual precipitation. About half of the additional precipitation amount produced by an increasing trend above the long-term average leaves the watershed in the form of surface runoff. The converse is true for a decreasing trend in precipitation. The sensitivity of streamflow in the LWREW to decade-long variations in precipitation was between 4 and 6, meaning that, at decade scales, a 10% increase or decrease in precipitation leads to a 40% to 60% increase or decrease in streamflow, respectively. This high sensitivity emphasizes the need to consider such decade-scale precipitation and streamflow in the planning of water resources infrastructure and development of long-term management strategies for efficient utilization of water resources.

Last Modified: 7/28/2014
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