Abstract
Wave energy is a major driver for coastal processes, such as erosion, sediment transport, and hydrodynamics. For this reason, it is important for wave energy to be considered in the process of site selection, design, and implementation of conservation and restoration projects. In areas influenced by boat wakes, no-wake, or idle speed only, zones have been established to protect sensitive shorelines. These zones are primarily marked with moored buoys, which are routinely stopped at abruptly by approaching boaters or accelerated out of at the end of one of these zones. An abrupt stop or start by a vessel can produce a type of wave, known as a self-reinforcing wave, that propagates above the current mean water level. The atypically large structure of these waves can lead to negative impacts on sensitive shorelines and this has been observed, anecdotally, where areas at the edge of no-wake zones have disproportionately more erosion. To explore the relationship between proximity to no-wake zones and erosion, a field experiment was performed in summer 2020 where the waves impacting the shorelines from multiple vessel approaches were evaluated. Vessel approaches consisted of 5 replicates each of 1) cruising parallel, 2) stopping parallel, 3) stopping perpendicular, 4) stopping at a 45-degree angle, and 5) accelerating parallel to shore. Waves were measured using DIY wave gauges spread across a 160m stretch of shoreline. Results indicated that wave heights impacted the shoreline were twice as high within the first 40m of accelerating out of a stop and that there was no difference in wave heights for any of the stopping treatments or cruising treatment within the first 40m. Beyond 40m, cruising and accelerating wave heights were higher than the other treatments.
