Living Shorelines in Tidal Wetlands
Mark Cadotte
The rock and concrete industry is the 3rd largest contributor to GHGs and carbon emissions worldwide accounting for roughly 10% of emissions globally. If they were a country, it would rank 3rd highest in emissions behind only USA and China. Recently, industry has seen initiatives for hard armoring alternatives and the use of nature-based solutions to provide long term resiliency to our infrastructure. Initiatives have come from acts including the WRDA 2020 and 2022 reaffirming the commitment to have greater use of nature-based projects by ensuring natural alternatives are fully evaluated by the USACE. Executive Orders and the 2030 Greenhouse Gas Pollution Reduction Target were issued to use nature-based solutions to enhance carbon sinks. In 2021, FEMA introduced its BRIC (Building Resilient Infrastructure and Communities) program encouraging and incentivizing the use of nature-based solutions for flood hazard mitigation and awarded $1 billion through this program. High Performance Turf Reinforcement Mats (HPTRMs) are considered nature based and bonus points are awarded within the BRIC framework. In 2023, FEMA published the fiscal year 2023 funding opportunities for the BRIC program, totaling $1.8 billion. A number of these successfully funded BRIC projects have incorporated HPTRMs into design, including some in California.
Studies have shown vegetated HPTRMs can provide a quantifiable reduction in carbon footprint, carbon emissions, and increased carbon sequestration through nature-based solutions while also promoting groundwater recharge. Recent testing has also demonstrated a drastic improvement in water quality and TSS reduction using vegetated HPTRMs when compared to rock, which matches the data represented by the EPA Stormwater Technology Fact Sheet.
Applying these concepts of reduced emissions and improved water quality, we will examine the emissions and overall impact of using HPTRMs in lieu of riprap for a 3,000-acre natural tidal wetland, creating beneficial habitat for native fish and wildlife, including the Delta Smelt. This wetland also improves flood management in the northwestern portion of the Sacramento–San Joaquin Delta. The use of HPTRMs reduced the number of trucks required to armor the levee by 3,470 when compared to rock riprap. This obviously has considerable tangible impacts on carbon vehicle emissions, crash potential, noise pollution, congestion, health care costs, and dust for area residents and the environment.
Learning Objectives
- Vegetated alternatives to "Hard Armoring".
- Carbon footprint reduction using vegetated HPTRMs when compared to "Hard Armoring".
- Improved water quality when using vegetated solutions vs rock or "Hard Armoring".