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USUING STREAM MORPHOLOGY CLASSIFICATION TO MANAGE ECOLOGICAL RISKS FROM LAND USE CHANGES IN THE LMR WATERSHED
Citation:
Schultz**, C A., M A. Morrison**, J SchubauerBerigan, F B. Daniel*, M E. Troyer, AND M. B. Griffith. USUING STREAM MORPHOLOGY CLASSIFICATION TO MANAGE ECOLOGICAL RISKS FROM LAND USE CHANGES IN THE LMR WATERSHED. Presented at 2003 OCV SETAC Annual Meeting: Emerging Challenges for Environmental Science in the Ohio Valley Region, Cincinnati, OH, 05/15-16/2003.
Description:
Changes in the amount and types of land use in a watershed can destabilize stream channel structure, increase sediment loading and degrade in-stream habitat. Stream classification systems (e.g. Rosgen) may be useful for determining the susceptibility of stream channel segments to erosion and bank failure, and may help to identify stable endpoints for stream channel restoration and BMP (best management practice) placement. A stream classification system is currently being considered by the EPA Office of Water. We are using this approach to determine if streams can be classified to assess the risk of increased erosion resulting from changes in land use. One of the hypotheses associated with the survey work is that a stream can resist change up to a certain level, threshold, but beyond that threshold the stream will change classifications and alter both its channel formation and erosional properties. Understanding these thresholds will assist in the evaluation of risks from development and aid in the design and implementation of both structural and non-structural BMPs.
We plan to map stream reaches within the Little Miami Watershed, where we are also monitoring stream health, water quality and land use (using remote sensing). Mapping will be accomplished using the Adistance and direction@ method, where distance is measured using a tape measure and direction is measured with a compass. From any known point on a map the location of any other point can be plotted using this method. The changes in elevation are measured using a laser level which emits a beam of visible red light in a horizontal plane, the height to this beam is measured and the change in elevation is calculated. Location and elevation measurements are made at various locations along the stream and across the stream, such as the terrace, the slope of the banks and across the stream bed. From this data it is possible to construct detailed maps of stream bottom, banks and adjacent land using GIS software. These maps will be used to precisely position experimental equipment, determine the extent of bank erosion and the movement of the stream channel over time. Additionally the geographical and geological data collected during the mapping can be used to classify the streams based on their bed materials, slope, cross-section and map view. The characteristics used in classifying the stream are the result of the movement of water in the stream channel, particularly during storm events. Changes in land use cause changes in how water moves through the stream system and therefore can alter the physical characteristics of the stream, resulting in a different classification. The goal of coordinating physical, chemical and biological measurements, across ecoregions and land use gradients, is to develop an understanding of the relationship between land use and the biological and geomorphological properties of the stream.