From grey to green: Efficacy of eco‐engineering solutions for nature‐based coastal defence

Abstract

Climate change is increasing the threat of erosion and flooding along coastlines globally. Engineering solutions (e.g. seawalls and breakwaters) in response to protecting coastal communities and associated infrastructure are increasingly becoming economically and ecologically unsustainable. This has led to recommendations to create or restore natural habitats, such as sand dunes, saltmarsh, mangroves, seagrass and kelp beds, and coral and shellfish reefs, to provide coastal protection in place of (or to complement) artificial structures. Coastal managers are frequently faced with the problem of an eroding coastline, which requires a decision on what mitigation options are most appropriate to implement. A barrier to uptake of nature-based coastal defence is stringent evaluation of the effectiveness in comparison to artificial protection structures. Here, we assess the current evidence for the efficacy of nature-based vs. artificial coastal protection and discuss future research needs. Future projects should evaluate habitats created or restored for coastal defence for cost-effectiveness in comparison to an artificial structure under the same environmental conditions. Cost-benefit analyses should take into consideration all ecosystem services provided by nature-based or artificial structures in addition to coastal protection. Interdisciplinary research among scientists, coastal managers and engineers is required to facilitate the experimental trials needed to test the value of these shoreline protection schemes, in order to support their use as alternatives to artificial structures. This research needs to happen now as our rapidly changing climate requires new and innovative solutions to reduce the vulnerability of coastal communities to an increasingly uncertain future.

Shear-induced instabilities of flows through submerged vegetation

“…While there are many infrastructural solutions on flow management, there is also an emerging interest in utilising aquatic vegetation, as it is part of the natural habitat helping to sustain our ecosystems. Above all, compared to artificial measures, aquatic vegetation has the promising abilities of adapting to the local environment and self-repairing after destructive events (Morris et al 2018). On the other hand, flows through vegetation are challenging to model due to interactions between the two.…”

Flow Resistance and Energy Dissipation in Supercritical Air‐Water Flows Down Vegetated Chutes

“…In terms of coastal and flood protection, flow or wave attenuation and sediment retention are valuable ecosystem services of coastal and riverine ecosystems (Barbier et al, 2011;Gutiérrez et al, 2011). New insights into the hydraulic efficiency and cost efficiency of natural and nature-based solutions pave the way for integration of such solutions into engineering design processes (de Vriend et al, 2015;Morris et al, 2018;Narayan et al, 2016;Schoonees et al, 2019;Sutton-Grier et al, 2018).…”

Experimental evaluation of the robustness of the growth–stress tolerance trade‐off within the perennial grass Dactylis glomerata

“…Seeds from each D. glomerata population were sown at the CEFE-CNRS research centre in Montpellier, France (43°6′N, 3°8′E), in seedling trays in February 2013 and were then transplanted into 4-L, 18-cm-diameter pots in May 2013 then maintained over years. In pots, as roots were equally limited in depth for all the populations, plant drought survival mirrored plant dehydration tolerance instead of dehydration avoidance(Volaire, 2008(Volaire, , 2018. Each 4-L pot contained four clonal individuals from a single accession (population hereafter) to ensure soil cover close to field conditions, with 12 replicate pots per population.…”