Author(s): Margaret Chen; Anne Lise Montreuil; Kirsten Schotman

Linked Author(s): Margaret Chen

Keywords: Coastline; Erosion; Building with nature; Coastal defense; Sand fences

Abstract: Sandy coastlines are under threat of erosion. The erosion process is being driven by sea-level rise, meteorological and marine forces, anthropogenic activities, and other factors. Taking the approaches of building with nature and nature-based coastal defense solutions have emerged as an indispensable part of achieving sustainable coast management practices. Sand fences have been considered as a sustainable way of countering beach erosion and stimulating dune growth for a resilient beach-dune system. This study therefore sets out to investigate the feasibility of ecosystem-based natural materials for constructing sand fences at the Belgian coast. The investigations are twofold: (1) selection of materials, design, and configuration of structure; and (2) field tests and assessment. An important prerequisite of material selection is that all materials should be natural, stable but moveable when needed, and have the least impact on the ecosystem. Based on the local situation, three materials were chosen: bamboo, tree cuttings, and perforated wooden panels. To date, there is no consistent protocol exists for constructing sand fences, however, good practice rules for design are collected and used as guidelines in the design process. Three fences were constructed and tested for sand trapping in April 2021 at the Belgian coast (Groenendijk). Two Terrestrial Laser Scanners were deployed, and placed at the direction of upwind and downwind of the fences. The results showed a ranking of the 3 chosen materials. Bamboo scores best, collecting a sand volume of 301 cm³ at a rate of 147 cm³/h or 2.4 cm³/min. The tree cuttings come second collecting a sand volume of 62 cm³ at a rate of 26.2 cm³/h or 0.44 cm³/min. The perforated wooden panels do not score very well, eroding a sand volume of 814 cm³ at a rate of 153.5 cm³/h or 2.6 cm³/min. The first sets of investigations provide valuable data for assessing future sand trapping strategies at the coastal sites where densely populated with high social and economic activities. It highlights further the imminent need for effective design and implementation of adaptive measures for the resilient coastline.

DOI: https://doi.org/10.3850/IAHR-39WC2521711920221738

Year: 2022