Structural Settlement Evaluation of Low-Crested Breakwaters Made of Geotextile Tubes

One of the efforts to improve successful in handling coastal erosion is to develop a coastal protection structure to be called as PEGAR, an acronym of Pemecah Gelombang Ambang Rendah or Low-Crested Breakwater (hereinafter referred to as LCB). The use of geotextile tubes filled with sand in LCB construction has been widely practiced since 2010. LCBs play a role in breaking waves and dampening their energy before reaching the coast. The breaking of the waves generates a rotating current behind the structure which results in the deposition of sediment supplied through the crest of the structure and longshore drift. Subsequent sedimentation processes produce sedimentary deposits and forms new shorelines (salient) and even forms tombolo. Through these two sediment supplies, natural sand filling and beach widening can take less than one season. However, from the experience of applying LCBs in the field, there are several LCBs that experience structural degradation. In addition, it even subsided after several years of operation which resulted in a decline in its function as a coastal protection. Evaluations and suggestions for improving a more stable and durable low-crested structure are given in this paper.