Grantee Research Project Results
A Review of Steep Channel Design MethodologiesEPA Grant Number: U915634
Title: A Review of Steep Channel Design Methodologies
Investigators: Crowe, Joanna C.
Institution: Johns Hopkins University
EPA Project Officer: Boddie, Georgette
Project Period: August 1, 1999 through August 1, 2002
Project Amount: $102,000
RFA: STAR Graduate Fellowships (1999)
Research Category: Academic Fellowships , Ecological Indicators/Assessment/Restoration , Fellowship - Earth Sciences
Steep stream design has become one of the most difficult issues facing the restoration community. Many channels subject to restoration are those that were once moderately sloped and have eroded to a steep gradient. These channels have high energy flow over an erodible bed and a channel profile, with a large elevation drop over a short distance. The objective of this research project is to provide information from data gathered in the field, coupled with flume studies of steep channel hydraulics, to evaluate different design methodologies.Approach:
Step-pool sequences are the most common solution used in the redesign of steep channel segments. Bedform-design specifics usually are constrained by an established channel slope and channel width. Therefore, step-pool designs are based on the combination of discharge, step forming clast size, individual step spacing, and pool depth chosen. There are a number of different methodologies in use for determining these variables, yet there is not one method that has been proven most successful. Recent literature includes studies focused on the hydraulics of steep streams, resistance of step sequences, and the rearrangement of natural step-pool sequences during a large flood event. Results from this research provide some guidance concerning the behavior of step-pool bedforms and steep channels. Although the objective of many design channels is not to mimic nature, the information provided by the data gathered in the field coupled with flume studies of steep channel hydraulics can be useful in the evaluation of different design methodologies.Supplemental Keywords:
fellowship, step pools, steep channels.