THE REACH SENSITIVITY INDEX (RSI) FOR MAPPING RIVERS AND STREAMS

Abstract

ABSTRACT Strategies for identifying and protecting sensitive inland areas under U.S. Environmental Protection Agency (USEPA) management have focused on major rivers and have built on the Environmental Sensitivity Index (ESI) approach developed by the National Oceanic and Atmospheric Administration (NOAA) for marine environments. A watershed approach has been refined and applied to smaller rivers and streams in the southeastern United States. Existing standardized river classification schemes did not adequately address oil spill response issues. Thus a new stream reach sensitivity scheme was developed, based on (1) the degree of difficulty anticipated for the containment and recovery of spilled oil, and (2) the sensitivity and vulnerability of associated wetlands. This scheme considered the following factors: navigability, water flow patterns, stream size, occurrence of suitable collection points inherent in the stream type, and channel leakage and bifurcation. A reach sensitivity index (RSI) was prototyped using streams in South Carolina, and then was applied to the Leaf River watershed in Mississippi. The RSI is on a scale of 1 to 10. The final atlas and digital product are maps at a scale of 1:100,000 showing the RSI, sensitive biological and human use resources, and potential access and collection points.