Submitted to: American Water Resources Association Summer Specialty Conference
Publication Type: Proceedings
Publication Acceptance Date: 7/1/2002
Publication Date: 7/1/2002
Citation: Interpretive Summary: Decade-scale precipitation variations and trends have been recognized in many regions of the Great Plains, with the latest increase in mean annual precipitation during the 1980's and 1990's. This study is an exploratory analysis that shows that decade-scale precipitation variation influenced groundwater levels and spring flows in the Arbuckle formation of Oklahoma. Over the wet period of the 1980's and 1990's, the mean annual groundwater elevations rose by about 10 ft and mean annual spring flows doubled. Spring flow was found to be the most sensitive variable to change. If precipitation returns to the record normal, Byrds Mill Spring should return to the flows experienced during the 1960's and 1970's. While the numerical conclusions are specific to the site studied, the relative ease of the analysis and the unambiguous results make it possible to recommend these methods for water resources planning and management. Moreover, the importance of studying past decade-scale precipitation, groundwater and spring flow variations should increase in value as ongoing research in climate variation prediction bears fruit.
Technical Abstract: Decade-scale precipitation trends have been recognized in many regions of the Great Plains. In particular, two decades of above average precipitation prevailed in Central Oklahoma at the end of the 20th century. Previous studies have concluded that above average precipitation resulted in a substantial increase in stream flow. The interaction between precipitation and groundwater level from 1960 to 2000 in an Arbuckle formation well and spring in South-Central Oklahoma was examined. An 11-year moving average of annual precipitation showed an increase from a low of about 35 inches to a high of 42 inches during the period. Groundwater levels showed a highly correlated pattern with a 10 ft variation, which was mimicked by flow of the Byrds Mill Spring that ranged from about 6 to 13 ft3/s. Analyses of these time series allow the estimation of the groundwater sensitivity to precipitation changes. The results show that long-term variations in annual precipitation can have significant impact on recharge and subsequent stream base flows, which require more consideration in water resources planning and management.