Hard Structures for Coastal Protection, Towards Greener Designs

Abstract

Over recent years, many coastal engineering projects have employed the use of soft solutions as these are generally less environmentally damaging than hard solutions. However, in some cases, local conditions hinder the use of soft solutions, meaning that hard solutions have to be adopted or, sometimes, a combination of hard and soft measures is seen as optimal. This research reviews the use of hard coastal structures on the foreshore (groynes, breakwaters and jetties) and onshore (seawalls and dikes). The purpose, functioning and local conditions for which these structures are most suitable are outlined. A description is provided on the negative effects that these structures may have on morphological, hydrodynamic and ecological conditions. To reduce or mitigate these negative impacts, or to create new ecosystem services, the following nature-based adaptations are proposed and discussed: (1) applying soft solutions complementary to hard solutions, (2) mitigating morphological and hydrodynamic changes and (3) ecologically enhancing hard coastal structures. The selection and also the success of these potential adaptations are highly dependent on local conditions, such as hydrodynamic forcing, spatial requirements and socioeconomic factors. The overview provided in this paper aims to offer an interdisciplinary understanding, by giving general guidance on which type of solution is suitable for given characteristics, taking into consideration all aspects that are key for environmentally sensitive coastal designs. Overall, this study aims to provide guidance at the interdisciplinary design stage of nature-based coastal defence structures.

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).…”

Enhancing the Ecological Value of Sea Dikes

“…One way of categorizing nature-based solutions is to distinguish between "fully natural solutions", "managed natural solutions", "hybrid solutions that combine structural engineering with natural features" and "'environment-friendly' structural engineering" ( [31], similar categorization in [32]). To date, guidelines for the design, implementation, monitoring and maintenance of nature-based coastal engineering solutions are limited [31].…”

“…Based on the findings of the present review, potential for ecological enhancement of sea dikes has been found regarding the foreshore composition, dike surface protection measures (vegetated dike covers, hard revetments and dike roads) and the slope inclination. A schematic sketch of a sea dike system with nature-based solutions is given in [32].…”

An Overview of the Expected Shoreline Impact of the Marine Energy Farms Operating in Different Coastal Environments

“…At present, most of the erosion management strategies involve the use of hard solutions, such as seawalls, interlocking blocks, rubble mound, detached breakwaters, groins, dunes, tyres or jetties [18][19][20][21]. Nevertheless, there are studies indicating that this approach is not the best way to tackle coastal erosion.…”