Numerical Investigation and Analysis of Fishing Harbour Hydro-Morpho-Dynamics in Wave, Tide and Combined Wave-Tide Dominated Basins for Sustainable Coastal Development

Lakku, N. K. G.; Shevale, S.; Das, M., and Behera, M. R., 2024. Numerical investigation and analysis of fishing harbour hydro-morpho-dynamics in wave, tide and combined wave-tide dominated basins for sustainable coastal development. In: Phillips, M.R.; Al-Naemi, S., and Duarte, C.M. (eds.), Coastlines under Global Change: Proceedings from the International Coastal Symposium (ICS) 2024 (Doha, Qatar). Journal of Coastal Research, Special Issue No. 113, pp. 1070-1075. Charlotte (North Carolina), ISSN 0749-0208. Fishing harbours play a crucial role in the economic development of countries. While the impact of fishing harbours on the blue economy is significant and multifaceted, it is necessary to plan for the sustainable development of coastal structures, considering the minimal impact on coastal processes and shoreline stability. This article focuses on investigating the changes in shoreline morphology considering the fishing harbour development in wave dominant, tide dominant and combined wave and tide dominant basins. The representative sites, Harnai (wave dominated), Sakharinate (tide dominated) and Rajiwada (wave-tide dominated) play a key role in fishing activities along the coast of Maharashtra, India. The major issues at these sites are insufficient tranquility and frequent siltation in the entrance channel, which results in a smaller operational window for fishing harbour operations. Considering the diverse hydrodynamic conditions and challenges at respective sites, the numerical simulations were carried out by coupling the spectral wave model (MIKE21-SW), hydrodynamic (MIKE21-HD) and sand transport (MIKE21-ST) models to fully capture and understand the wave processes and tide hydrodynamics on bed level changes. The developments (breakwaters/training walls) were proposed to streamline fishing activities by altering the existing wave and tide hydrodynamics and sedimentation pattern, with less impact on the stability of adjacent beaches and coastal landforms. The developments in wave dominant basins should focus on the breakwater alignment to achieve sufficient tranquility and less siltation in the harbour basin. In a tide dominant basin, it is advised to position the training wall such that there is enough flood and ebb current to accomplish zero net sediment transport in the channel. When there is a combined wave-tide basin, the ebb current needs to be strong enough to remove the sediments that the waves and flood current have brought in. This regional-scale, multi-basin study provides important inferences and guidelines for the sustainable development of fishing harbours and enhanced blue economy.