Cost Comparison Between Hard and Soft Approaches Adapted as Preventive Methods of Beach Erosion

Abstract

Yeon, Y.J. and Lee, J.L., 2021. Cost comparison between hard and soft approaches adapted as preventive methods of beach erosion. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 519–523. Coconut Creek (Florida), ISSN 0749-0208. To protect the properties behind a beach, submerged breakwater, which is a representative hard approach, or beach nourishment, which is a representative soft approach, has been performed. The submerged breakwater protects the facilities behind the beach by controlling waves to mitigate erosion. This study estimates the cost required to secure a buffer section for the wave inflow of 30-year return period using submerged breakwater and beach nourishment methods for Sokcho Beach (Sokcho-si, Gangwon-do), one of the coastal maintenance project areas, and conducts economic assessment of the two methods. For the submerged breakwater method, the construction cost was calculated using the shoreline observation data, which were observed four times a year for about 8 years. For the beach nourishment method, the construction cost was calculated using the sand loss half-life (shoreline retreat over time) considering that the nourished sands cannot be maintained. The result showed that beach nourishment could obtain a higher economic feasibility. By enhancing sand maintenance, beach nourishment was evaluated as more economical than the hard approach when the sand loss rate (k), which determines the half-life of beach nourishment, was lower than 0.167 yr–1. Furthermore, beach nourishment is highly evaluated because it is an eco-friendly construction method, and it will be more effective when combined with other soft approaches.