A fundamental concept within the field of fluvial geomorphology states that, as one moves downstream within a watershed, there is a predictable and quantifiable rate of increase in bankfull-channel dimensions. The early efforts to describe and document this concept can largely be attributed to the work presented in three interrelated publications.
- Emmett, W.W. and Leopold, L.B., 1963, A dimensionless rating curve: U.S. Geological Survey, Water Resources Division Bulletin, August, 1963, pp. 22–24.
- Leopold, L.B., Wolman, M.G., and Miller, J.P., 1964, Fluvial Processes in Geomorphology: W.H. Freeman and Company, San Francisco, 522 p.
- Dunne, T., and Leopold, L.B., 1978, Water in Environmental Planning: W.H. Freeman and Company. New York, New York, 818 p.
For a more complete discussion of the historical development of this concept, the reader is directed to:
- Emmett, W.W., 2004, A historical perspective on regional channel geometry curves: U.S. Department of Agriculture, Stream Notes accessed January 23, 2006, at http://stream.fs.fed.us/news/streamnt/jan04/jan04_02.htm.
In a recently completed investigation, the US Geological Survey (USGS) Indiana Water Science Center has identified regional channel-dimension relations for non-urban wadeable streams in Indiana. In the USGS report, regional channel-dimension curves are presented as a combination of plots and regression equations that identify the relations between drainage area and the bankfull-channel dimensions of width, mean depth, and cross-sectional area.
The design of the USGS investigation included:
- Data collection at stable sites which span a broad range of drainage areas
- Sites representing the three largest physiographic regions of Indiana
- A focus on the most natural areas of Indiana (e.g. Hoosier N.F., Ind. Dunes N.L., state parks, etc…)
- Sites with sufficient field evidence to make a confident determination of bankfull stage
- The application of simple regression techniques to determine best-fit lines and equations
Following well-established methods, data were collected at 82 study sites to identify bankfull stage, determine the dimensions of bankfull width, mean depth, and cross-sectional area, and document channel geometry characteristics that allow for determinations of channel classification. From these data, regional channel-dimension equations were developed for the three largest physiographic regions of Indiana—the Northern Moraine and Lake region, Central Till Plain region, and Southern Hills and Lowlands region.
The USGS regional bankfull-channel dimension report for non-urban wadeable streams in Indiana is available through the USGS Publications Warehouse and may be accessed via the following link:
Robinson, B.A., 2013, Regional bankfull-channel dimensions of non-urban wadeable streams in Indiana: U.S. Geological Survey Scientific Investigations Report 2013-5078, 33 p.