Geomorphic Approach for Beach Downdrift of Fishing Ports and Marinas: Parabolic Model and Software MeePaSoL

Coastal erosion problems associated with a fishing port or marina on sandy coast are caused by imbalance of longshore sediment transport and bay shape formation on downdrift. Regardless of the availability of littoral transport, the tip of its outer breakwater would behave as an updrift control point for an embayed beach to form, by combined wave diffraction-refraction aided by nearshore current circulation. Conventional approach to mitigate downdrift erosion have applied laboratory tests and numerical modelling, together with hard structures (seawalls, groins and detached breakwaters). On the contrary, an efficient geomorphic model with software MeePaSoL is now available, which can readily sketch the curved shoreline planform in static equilibrium or verify the stability of an existing planform, without laborious laboratory tests and complicated numerical programming. Not only is this geomorphic approach a reliable method, but it also serves a purpose being a useful tool for planning an initial breakwater layout and examining the effects of relocating an existing breakwater for port expansion projects. By combining the parabolic model with software MeePaSoL, an appropriate shore protection scheme can also be devised to achieving a resilient coastal environment. Examples applying this geomorphic approach for mitigating downdrift beach erosion is explained, together with four case studies for the benefits to coastal profession.