Assessing Ecosystem-Based Natural Materials for Resilient Coast in Belgium

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. Building with nature and nature-based coastal defense solutions have emerged as an indispensable part of achieving sustainable coastal management practices. 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 experiments and assessment. Based on the local situation, three materials were chosen: bamboo, tree cuttings, and perforated wooden panels. To date, there is no consistent protocol for constructing sand fences, however, good practice rules for design are collected and used as guidelines. Three fences were constructed and tested for sand trapping in April 2021 at the Belgian coast (Groenendijk). 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.