APPENDIX C: MITIGATION ALTERNATIVES
• Wetland protection • Erosion and sedimentation control • Stream/River restoration • Best management practices
• Dumping regulations • Farmland protection
Wetland Protection Wetlands are often found in floodplains and topographically depressed areas of a watershed. Many wetlands receive and store floodwaters, thus slowing and reducing downstream flows. They also serve as a natural filter, which helps to improve water quality, and they provide habitat for many species of fish, wildlife and plants. Erosion and Sedimentation Control Farmlands and construction sites typically contain large areas of bare
exposed soil. Surface water runoff can erode soil from these sites, sending sediment into downstream waterways. Erosion also occurs along stream banks and shorelines as the volume and velocity of flow or wave action destabilize and wash away the soil. Sediment suspended in the water tends to settle out where flowing water slows down. This can clog storm drains, drain tiles, culverts and ditches and reduce the water transport and storage capacity of river and stream channels, lakes and wetlands. There are two principal strategies to address these problems: minimize erosion and control sedimentation. Techniques to minimize erosion include phased construction, minimal land clearing, and stabilizing bare ground as soon as possible with vegetation and other soil stabilizing practices. The City of Raleigh has adopted a soil and erosion control ordinance. Stream/River Restoration There is a growing movement that has several names, such as "stream conservation," "bioengineering," or "riparian corridor restoration." The objective of these approaches is to return streams, stream banks and adjacent land to a more natural condition, including the natural meanders. Another term is "ecological restoration," which restores native indigenous plants and animals to an area. A key component of these efforts is to use appropriate native plantings along the banks that resist erosion. This may involve retrofitting the shoreline with willow cuttings, wetland plants, or rolls of landscape material covered with a natural fabric that decomposes after the banks are stabilized with plant roots.
In all, restoring the right vegetation to a stream has the following advantages: • Reduces the amount of sediment and pollutants entering the water • Enhances aquatic habitat by cooling water temperature • Provides food and shelter for both aquatic and terrestrial wildlife • Can reduce flood damage by slowing the velocity of water • Increases the beauty of the land and its property value • Prevents property loss due to erosion • Provides recreational opportunities, such as hunting, fishing and bird watching • Reduces long-term maintenance costs
Wake County Multi-Jurisdictional Hazard Mitigation Plan 2019
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