Wisconsin hydraulic geometry regional curves

Science Center Objects

The USGS is helping develop regional regression curves that relate channel geometry characteristics with streamflow and basin characteristics to improve the design of channel restoration projects for small, ungaged streams with limited data and streamflow relations.

Photograph of a bankfull regional curves data collection reach along the Brule River, 2006

Bankfull regional curves data collection reach along the Brule River, 2006

Problem

Many channel restoration projects are being undertaken throughout Wisconsin on small streams by various federal, State, and local agencies with limited data and streamflow relations that would be useful for design of projects. Stream restoration projects using natural-channel design are often based on the bankfull flow characteristics of the stream to accommodate streamflow and sediment transport without excessive erosion or deposition (for example Rosgen, 1998). Regional regression curves that relate channel geometry characteristics (width, depth, cross-sectional area) with streamflow (mean discharge, flood discharges) and basin characteristics (drainage area, channel slope, land cover, precipitation, and snowfall) are needed for design and are generally lacking for Wisconsin. Regional regression equations are a necessity when working on small, ungaged streams.

Approach

A full protocol was jointly developed between the WI USGS, USFS, and NRCS over the first years of data collection. The field methods include surveying cross sections and a longitudinal profile, characterizing the substrate, and photo documentation. In the office, information from the streamgage record is combined with the calculated channel geometry. Channel geometry relations will be developed with basin characteristics and calculated bankfull channel characteristics. Data analysis and results may be grouped by ecoregions, urban v. rural or agricultural streams, type of stream (ephemeral v. perennial), or flow condition (base-flow dominated streams vs. flashy streams).

Study Status

From 2006 to 2009 in Wisconsin, the USGS, USFS, and NRCS partnered to develop the methods for site selection and data collection and have collected data at 11 Wisconsin sites. Personnel at all three agencies have been trained in the data collection methods and data analysis. The results and methods of the preliminary data analysis are unpublished.