Soil moisture and rainfall intensity thresholds for runoff generation in southwestern Wisconsin agricultural watersheds
Article first published online: 2 AUG 2012
Copyright © 2012 John Wiley & Sons, Ltd.
Volume 27, Issue 25, pages 3521–3534, 15 December 2013
How to Cite
Radatz, T. F., Thompson, A. M. and Madison, F. W. (2013), Soil moisture and rainfall intensity thresholds for runoff generation in southwestern Wisconsin agricultural watersheds. Hydrol. Process., 27: 3521–3534. doi: 10.1002/hyp.9460
- Issue published online: 2 DEC 2013
- Article first published online: 2 AUG 2012
- Accepted manuscript online: 27 JUN 2012 11:04AM EST
- Manuscript Accepted: 20 JUN 2012
- Manuscript Received: 26 APR 2011
- manure management;
- soil moisture;
The goal of this study was to improve understanding of the factors that influence runoff generation during non-frozen ground periods in small agricultural watersheds in southwestern Wisconsin where the landscapes are controlled by dolostone bedrock in order to provide agricultural producers with a manure management tool. Six small watersheds (ranging from 6 to 17 ha) within two southwestern Wisconsin farm sites (Discovery Farms Program (DFP) and Pioneer Farm (PF)) were instrumented, and surface runoff was continuously monitored from 2004 to 2007. The soils in all watersheds were formed in deep (~1 m) loessial sites. A direct-plant management strategy and corn-soybean crop rotation were utilized within watersheds at DFP. A conventional tillage system (chisel plow in the fall followed by soil finisher in the spring) and a corn-oat-alfalfa crop rotation were utilized within watersheds at PF. At PF, the amount of precipitation leaving the landscape as surface runoff (1.8%) was two times greater compared to DFP (0.9%), indicating that the direct-plant management system was better at retaining precipitation than the chisel plow/soil finisher system. Using breakpoint regression analysis, a non-linear response in runoff generation with antecedent soil moisture (ASM) was observed with a threshold ASM of 0.39 cm3cm−3 (approximately 80% of total porosity) for all six watersheds. Below this threshold, runoff coefficients were near zero. Above this threshold, runoff coefficients increased with ASM. A non-linear response in runoff generation with maximum 30 min rainfall intensity (I30) was also observed, and threshold I30 values increased as ASM decreased and as crop cover increased. Copyright © 2012 John Wiley & Sons, Ltd.