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3 TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

3 2021

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Prediction of wetland loss due to sea level rise around the largest port area in Latin America

Alfredini P., Arasaki E.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

2021

Vol. 15 No. 3

677--682

Santos’s mangroves are important wetlands located in Brazilian coast, a fishing area inside Santos Bay. The overall healthy mangroves area along the riparian zones influencing the Santos Estuary is around 25.20 km2. The resulting tidal level recorded from Port of Santos tide gauge (from 1940 to 2014), also located in the estuary, shows consistent increasing trend. One healthy mangrove was selected for a previous qualitative biological survey to better understand the characteristics of the habitat to be monitored and evaluated about the possible impacts in the next decades. The mangroves situated a few meters upper from the sea level and some other areas have the risk to be submerged till 2085 which will seriously affect the riparian mangroves biome. Indeed, the mangrove area is confined downward by the low tide level and upward by existing structures, roads, rural and urban areas.

Impact of hydrotechnical structures on forming the tombolo oceanographic phenomenon in Kołobrzeg and Sopot

Specht C., Lewicka O., Specht M., Zblewski S.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

2021

Vol. 15 No. 3

687--694

The process of global sea level rise is causing several significant changes in the coastal zone. Sea level rise and the frequency, strength and duration of storms are also occurring on the Polish coast. As a result, coastal protection measures, such as man-made engineering structure, are necessary. These engineering structures affect (among others) the marine ecosystem in different ways. Although the presence of such engineering structures can cause changes in the bathymetry of waterbody and the transport of sediments along the basin, it also slows down the erosion of the shoreline. For this reason, comprehensive knowledge of natural conditions, including dynamic and variable factors, is essential in the construction of a hydro-engineering structures. The correct determination of the environmental conditions helps to minimize environmental damage. Prior to interventions on the coast, the issues addressed in the paper should be analysed and studied. In this paper, the influence of shoreline structures on the main factors responsible for the development of tombolo phenomenon is discussed. In addition, the lithological diversity of surface sediments on which the rate of coastal erosion depends, is also discussed. An important element of the work is the descriptions of tombolo in Poland. They contain information on the causes of the phenomenon, as well as about the negative consequences of a disturbance of the hydrodynamic dynamics caused by the structure.

Behavior of sea level in the period of 1980 to 2017 on the port area of gulf of Maranhão, Brazil

Alfredini P., Arasaki E., Fortner E.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

2021

Vol. 15 No. 3

683--686

The Gulf of Maranhão, North Coast of Brazil, is one of the regions in the world with largest tidal ranges. The Port Area of Maranhão, in São Marcos Bay, represents the second most important in Brazil. The port facilities are naturally sheltered from swell, with nautical operations and maintenance dredging volumes directly conditioned by macro-tides, which exceed the 6.0 m tidal range, and associated tidal currents, which can reach 7.0 knots. In order to assess the behavior of sea levels in recent decades, in view of the influence of climate changes on tides in various ports around the world, a period of two lunar nodal tidal cycles of 18.61 years, from 1980 to 2017, was investigated using unpublished data recorded in tide gauges. The trend pattern obtained was analyzed statistically and, unlike many other port areas, a sensitive stability of the mean sea level was noted. An important conclusion is about the reduction in HHW and increasing in LLW, leading to a reduction in tidal ranges, in tidal currents and a significant reduction of the shear stress in the bottom, which may increase the dredging rates in the port areas in the next decades, due to an increasing siltation.