Reach Sensitivity Index Mapping of the Amite River Watershed in the Lake Pontchartrain Basin: A Tool for Watershed Restoration

Abstract

WEATHERS, D.H.; HAYES, M.O., and MICHEL, J., 2009. Reach sensitivity index mapping of the Amite River watershed in the Lake Pontchartrain basin: a tool for watershed restoration. Journal of Coastal Research, SI(54), 141– 151. West Palm Beach (Florida), ISSN 0749-0208. In recent years, the focus on issues regarding water quality has shifted from a local site-specific view of a problem toward a holistic view where the health and hydrologic functionality of entire watersheds are of concern. One measure of watershed health is fluvial geomorphology. The goal of this project was to map the morphology of the streams of the Amite watershed of the Pontchartrain Basin using a reach sensitivity index (RSI). The classification scale is based on stream geomorphology, hydrology, and ecological characteristics, where rank is given based on morphological complexity and associated wetlands. The RSI classification method used data from 18 field sites along with digital orthophoto quarter quadrangle 1-m resolution infrared aerial imagery, gap analysis program land cover data, and digital elevation models generated from light detection and ranging. In addition to mapping, issues related to watershed impairment and restoration were identified. Key anthropogenic impacts observed include sand and gravel mining, stream manipulation, profuse litter, and overall water quality. The watershed in this study is proximal to urban areas associated with New Orleans and Baton Rouge, Louisiana, so another theme, waterfront development, was also identified as a source of stream impairment. Reach sensitivity index stream classification can serve as a tool for conservation strategies and watershed restoration, where the ultimate goal is to restore natural hydrological and ecological functionality to impaired streams. Maps generated in the RSI project can further aid in regional planning, without which, rapid urban development and continued stream manipulation within the Amite and neighboring stream systems will result in accelerated watershed impairment and water-quality degradation.