Wave Transmission Through Pile–Rock Breakwater to Protect the Mekong Delta Coastal and Develop an Empirical Formula

The coastal erosion in the Vietnamese Mekong Delta (VMD) has become a serious problem for many years. Many solutions have been proposed to protect the coasts in many regions. The most popular constructions are pile–rock breakwaters. These structures consist of two rows of centrifugal piles which infilled rock. The wave flume experiments have been applied to build an experimental formula to evaluate wave reduction efficiency of breakwaters. But, there are some limitations of experimental situations, especially in case breakwater width is changed. Therefore, this paper focuses to (1) study the wave reduction ability of pile–rock breakwaters and (2) conduct wave flume experiments which take into account the change of breakwater width to determine the variation of wave spectra in front of and behind breakwaters. Results of experiments show that pile–rock breakwaters performed effectively because the wave transmission coefficients for emerged and submerged breakwaters are both low. Thus, the authors propose an experimental formula to determine the wave transmission coefficient and to be basement to design pile–rock breakwaters in the future.