TRENDS IN ANNUAL AND DAILY PRECIPITATION

Authors: Garbrecht, Jurgen; Schneider, Jeanne

Submitted to: Grazinglands Research Laboratory Miscellaneous Publication
Publication Type: Government Publication
Publication Acceptance Date: 4/8/2002
Publication Date: 4/8/2002
Citation: N/A

Interpretive Summary: An increasing precipitation trend was observed in the Great Plains during the last two decades of the 20th century. Corresponding changes in daily precipitation amount, number of rainy days, and distribution throughout the year are of particular interest to agriculture because they affect surface runoff, soil moisture availability, and land productivity. Changes sin daily precipitation as a result of the increasing precipitation trend were investigated for Kingfisher in central Oklahoma. About 60% of an increase in annual precipitation during the 1980-2000 period was attributed to an increase in the number of rainy days, and 40% was attributed to an increase in the daily amount of precipitation. Extreme precipitation events did not appear to be more frequent. On a seasonal basis, higher monthly precipitation in spring, early summer and fall were observed, which would primarily benefit winter wheat grazing and spring grain production.

Technical Abstract: Annual precipitation in the Great Plains was generally higher during the last two decades of the 20th century. Corresponding changes in daily precipitation amount, number of rainy days, and distribution throughout the year were investigated for Kingfisher in central Oklahoma. The number of rainy days increased, on average, by 5.6 days per year, and mean precipitation per rainy day increased, on average, by 0.035 inches per rainy day. About 60% of the increase in annual precipitation was attributed to an increase in the number of rainy days, and 40% was attributed to an increase in the daily amount of precipitation. Extreme precipitation events did not appear to increase. The trend towards more rainy days was believed to benefit soil moisture supply for crop production. On a seasonal basis, higher monthly precipitation in spring, early summer and fall were observed. This slight change in seasonal pattern may benefit primarily winter wheat grazing and spring grain production, whereas summer crops may receive less rain. Overall, this study demonstrated that changes in daily precipitation during the last two decades of the 20th century may have provided opportunities for adaptation and diversification, and may have supported a more sustainable and profitable production than during the 1960's and 1970's.