Using Geomorphology to Assess and Manage the Risks Associated with Clean Sediments in the Little Miami River Watershed (Southwestern OH)
2004
We are evaluating the use of stream geomorphology and related measurements in the assessment
and management of channel risks associated with stream impairment associated with clean
sediments. The relationships between various geomorphological variables have been used by
Rosgen and others to classify streams into groups that can be related to sediment transport or to
bed and bank stability. These methods may be used to predict and evaluate the sensitivity of
stream reaches to altered hydrologic regimes that subsequently result in bank destabilization and
excessive sediment transport. Factors, such as increased erosion and stream channel
destabilization, can result in impairment by excessive clean sediment. This project is intended to
determine (1) the most effective, timely and cost-efficient methods for collecting channel
morphology data, and (2) which variables may be used as indicators of increased risk of
impairment from suspended and bedded sediments. Previous research in the Little Miami River
(Southwestern Ohio) established thirty-five sites where data was collected for several years using
the U.S. EPA Environmental Monitoring and Assessment Program protocols. Eight of these
sites were selected for intensive surveying to determine the level of effort required to obtain
representative data for stream classification. Slope and sinuosity measurements from the surveys
resulted in the same Rosgen stream classification as that determined from measurements from
aerial photographs and topographic maps. This indicates that these types of data may be used in
place of extensive surveying at least in Southwestern Ohio. Other measurements such as pebble
counts, entrenchment and stream profile still require field visits. The extent to which a
qualitative rating system can be used is also being evaluated. The most important parameters for
determining the stability of stream geomorphology and near-stream erosion risks appear to be
slope, bed and bank material stability, incision and vegetative cover/type in the riparian zone.
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