GRAVEL BEACH NOURISHMENT AT A LOW-WAVE ENERGY ENVIRONMENT TO CONTROL THE EFFECTS OF GLOBAL WARMING

摘要

Tuvalu is a Pacific island nation with a low-wave energy environment which suffers from coastal erosion. When erosion occurs, sand beaches cannot maintain sufficient sand width, and foreshore slopes become steeper from frequent erosion effects. As a result, beaches are trapped in a vicious circle of becoming vulnerable due to incident waves. In order to repair or protect erosive beaches, beach nourishment can be used as a countermeasure which also minimizes environmental impacts. However, this is not a permanent solution and requires periodic renourishment after several years. Thus, to alleviate such problems, minimizing the period of renourishment is a necessary economical alternative. To discover the characteristics of the Tuvaluan coast and the effectiveness of nourishment, field surveys, numerical simulations and hydraulic model experiments were conducted. The effectiveness of both sand and gravel nourishments were analyzed through experiments.