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Title: PMAX VARIABILITY FROM CO2 DOUBLING USING LONG-TERM WEATHER TREND DATA

Author
item DANIEL, JOHN
item WILLIAMS, ROBERT

Submitted to: American Society of Agricultural Engineers Meetings Papers
Publication Type: Proceedings
Publication Acceptance Date: 7/1/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: Two forty-year (40) weather simulations were made with the weather generator CLIGEN, using modified and unmodified weather trend data from a site in Central Oklahoma. The data was modified by increasing the total precipitation by 10% over a 40-year interval to simulate the doubling of CO2. Results show an overall increase in Pmax for the modified weather simulation and monthly variation of storm intensity is seasonally related. This suggests that as storms become seasonally more intense, current agricultural practices such as tillage and livestock grazing may lead to increased impairment of water quality and sediment movement.

Technical Abstract: The rapid growth in human population has produced an ever increasing demand on energy and land development for agriculture. It is theorized that if a doubling of CO2 content in the global atmosphere occurs, an approximate 10 percent increase in mean global precipitation would occur by the middle of the next century. However, an increase in mean precipitation does not necessarily indicate that water will be available to the farmers at the period needed for optimum crop yield. Changes in precipitation patterns could change some agricultural practices as farmers respond to varying climatic conditions in order to minimize risks and maximize yields. The objective of this research is to evaluate the potential changes in selected storm parameters and monthly precipitation from a 10 percent increase of mean annual rainfall representing a doubling of CO2. Two forty-year weather simulations were made with the weather generator CLIGEN, using modified weather trend data from a site in Central Oklahoma. The data was modified by increasing the total precipitation by 10 percent over a 40-year interval to stimulate the doubling of CO2. Results of this study show that Pmax, the maximum storm intensity, is lowest for the dry period of the unmodified simulation. However, the wet period of the unmodified weather simulation and the dry and wet periods of the modified weather simulation display similar Pmax levels and characteristics. This suggests that an increased erosion potential found only in the wet period of the unmodified weather simulation is present in both dry and wet periods of the modified weather simulation. This suggests that higher CO2 levels in an atmosphere may produce more intense storm events and increase erosion potential.