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Benefits of Riprap

The over-Above_Below waterFOR WEB_thumb_thumb.jpgarmoring of much of the Naples Bay shoreline within the City is a major environmental issue. The prevalence of seawalls along the northern third of the bay has resulted in increased turbidity and reduced light passage through the bay’s waters. The energy in boat wakes reflects off the perpendicular walls without much absorption of that energy, keeping the water agitated and sediments constantly resuspended. Further, the vertical nature of a wall restricts mangrove establishment and does not provide the substrate necessary for estuarine shoreline community development. Both plants and animals have a hard time becoming established at such locations.

By utilizing riprap (rocky material slanted along the shoreline at a 2 or 3 to 1 slope) instead of a seawall, an estuarine community can develop within the nooks and crannies between the rocks. Riprap is an environmentally friendly alternative to seawalls. It creates a shoreline edge that can be used by oysters, crabs, fish, and mangroves. A shoreline with riprap protects the land from the erosional force of waves and efficiently absorbs wave energy because it is sloped. That, in turn, reduces turbidity and the resuspension of sediments, thus improving water clarity. Riprap is much more aesthetically pleasing than a seawall, is less costly, and requires less maintenance. If mangroves are already present along a shoreline, riprap can even be placed amongst the roots allowing enhanced protection without mangrove destruction. Even placing rocks in front of an existing seawall will alleviate some of the environmental impacts of a seawall while lengthening its life by reducing scouring effects at the base of the wall and decreasing the energy of waves pounding into it.

However, of great importance is that every one of the favorable qualities of riprap are tremendously enhanced if mangroves are planted among the rocks, plus they provide the added feature of filtering pollution from stormwater runoff. Mangroves can naturally recruit as well into riprap. Approximately a third of the shoreline of Naples Bay is armored by riprap, but only a small amount of that riprap has mangroves growing in it. Most of the Moorings Bay system is comprised of vertical seawalls with no mangroves. 

Click on the video to see the underwater benefits of riprap and the habitat it provides!!