Submitted to: Journal of Soil and Water Conservation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 25, 2007
Publication Date: November 1, 2008
Repository URL: http://hdl.handle.net/10113/22910
Citation: King, K.W., Smiley, P.C., Baker, B., Fausey, N.R. 2008. Validation of Paired Watersheds for Assessing Conservation Practices in Upper Big Walnut Creek Watershed, Ohio. Journal of Soil and Water Conservation. 63(6):380-395. Interpretive Summary: Federal dollars being spent on agricultural conservation programs is justified from successful plot scale studies of conservation practices and continues to increase. Quantitative watershed scale assessments of conservation practice implementation are limited. We designed a paired watershed study to quantify the effects of future watershed scale implementation of conservation practices. The findings from this study indicate that the paired design is a valid approach in the Upper Big Walnut Creek watershed in OH. The validation of the paired design suggests that we will be able to confidently quantify the hydrological, chemical, and ecological watershed scale impacts of conservation practices within the selected watershed.
Technical Abstract: Conservation practices are effective measures to combat sediment, nutrient, and pesticide transport at the plot scale. The impacts of watershed scale adoption of conservation practices on sediment, nutrient, and pesticide losses and the impacts on adjacent stream biota are not well understood. A paired watershed experiment was implemented to quantify the watershed scale hydrological, chemical, and ecological impacts of implementing conservation practices. The objective of this manuscript was to validate the use of the paired watershed design. One pair of channelized and one pair of unchannelized headwater watersheds located in the Upper Big Walnut Creek watershed in Ohio were identified and instrumented for this study. Physical, land use, and soil parameters were measured to assess the similarity in watershed characteristics within each pair. Channelized watersheds were more similar in watershed characteristics than the unchannelized watersheds. Additionally, one hydrology, eight water chemistry, and 15 ecological response variables were measured from 2005-2006 to examine the relationships within each pair of watersheds. A majority of all response variables in both the channelized and unchannelized watershed pairs were moderately correlated (r > 0.6). Additionally, the percent change required to detect a difference in the response variables was greater for the unchannelized system compared to the channelized system. Occurrence of detectable, increasing or decreasing, trends in the response variables through time were minimal. These results validate the paired design for both the channelized and unchannelized watershed pairs and suggest that conservation practice induced changes in hydrology, sediment, nutrient, and pesticide load, and/or fish communities should be quantifiable with relatively high confidence.