Ranking Secondary Channels for Restoration Using an Index Approach
Abstract
There are over 100 secondary channels in the Lower Mississippi River depending on river stage. Most have closure dikes in the upper reaches or throughout the channel to redirect flow towards the main channel to increase navigable depths. Recent environmental engineering practices in Corps Districts have recognized that many secondary channels can be reconnected without compromising navigation benefits. To accomplish this process, three indices were developed to rank the relative importance of secondary channels: Habitat Quality, Economy of Restoration, and Priority. Using aerial, geo-referenced video and aerial photography, five attributes or metrics of secondary channels were measured to establish an Index of Habitat Quality: Presence of gravel, Number of macrohabitats, Percent forested riparian on the island-side, Percent forested riparian on the land-side. Distance to Mississippi River mainline levee or natural bluff. The Economy of Restoration Index is a linear relationship between the number of dikes in a secondary channel requiring notching to restore flow and cost of construction. The Priority Index is the product of the Habitat Quality and Economy of Restoration Indices. Results indicate the presence of numerous side channels having moderate habitat quality with a relatively high number of dikes and only a small number of high-ranking channels that should be considered for conservation. Secondary channels can be restored relatively inexpensively, influencing large aquatic areas of riverine habitat, and most channels are within the Corps authorized boundaries, making it likely that cooperative restoration efforts with resource agencies will result in positive habitat gains.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 2012
- Accession Number
- ADA578514
Entities
People
- Bradley R. Lewis
- Jan J. Hoover
- K. Jack Killgore
- Ron Nassar
Organizations
- Engineer Research and Development Center