Physical Habitat Analysis Using the Riverine Community Habitat Assessment and Restoration Concept (RCHARC)

Book excerpt: Increased water resources demand in rivers regulated by U.S. Army Corps of Engineers dams has intensified the conflict between preservation of lotic ecosystems and economic benefits of stream regulatin or channel modification. The Riverine Community Habitat and Restoration Concept (RCHARC) facilitates evaluation of effects of different channel configurations or release patterns on fish habitat and can be used to balance water resources development and natural resource preservation. The RCHARC is applied to the Gavins Point Dam tailwater of the Missouri River as a case history to assess the effects of different reservoir release alternatives on habitat for native riverine warmwater fishes. Application of the RCHARC requires four steps. First a comparison standard must be selected which the project alternatives can be contrasted. Second, hydrologic and hydraulic features of the comparison standard having fish habitat significance are described and summarized as an annual series of monthly depth or velocity frequency distributions. Third, a similar approach is used to describe hydrologic and hydraulic features of the project alternatives. Fourth, the habitat value of each of the project alternatives is determined by similarity of their depth or velocity distributions to the distributions of the standard. The more similar an alternative is to the standard system, the higher it will be ranked.