Abstract:
Outlined is a practical approach to size and modify agricultural drainage channels to two-stage geometry to maintain drainage function and capacity while increasing channel stability. Two-stage channel systems consist of an inset channel and small floodplain (benches) within the ditch confines. The two-stage channel sizing procedure includes nine steps: (1) project identification; (2) data collection; (3) data analysis; (4) hydrologic evaluation; (5) conceptual channel system sizing; (6) project assessment; (7) design and/or final sizing; (8) construction; and (9) monitoring and assessment of performance. Channel width and depth dimensions are determined based on a weight-of-evidence approach that considers geomorphology measurements at the project site and throughout the watershed. The authors have developed spreadsheet tools to aid in evaluating the geomorphology of one and two-stage channels. Constructing a two-stage channel requires more excavation than traditional ditch maintenance, but benefits include improved conveyance capacity, a channel geometry that will be more self-sustaining, and improvement to in-stream habitat.
Footnotes
George E. Powell is an engineer for Brockway Engineering in Twin Falls, Idaho. Andrew D. Ward is a professor in the Department of Food, Agricultural and Biological Engineering at the Ohio State University in Columbus, Ohio. Daniel E. Mecklenburg is an ecological engineer for the Soil and Water Conservation Division of the Ohio Department of Natural Resources in Columbus, Ohio. Anand D. Jayakaran is an assistant professor at Clemson University, Georgetown, South Carolina.
- Copyright 2007 by the Soil and Water Conservation Society