Impacts of Navigation Channel Maintenance Dredging on the Coastal Processes of Chatham, Massachusetts

2001 ◽  
Author(s):  
Donald K. Stauble
Keyword(s):  
Coastal Processes ◽  
Navigation Channel ◽  
Channel Maintenance ◽  
Maintenance Dredging

scholarly journals EVALUATION OF THE RELATIONSHIPS BETWEEN NAVIGATION CHANNEL DREDGING AND EROSION OF ADJACENT BEACHES IN SOUTHERN BRAZIL

2012 ◽  
Vol 1 (33) ◽  
pp. 106 ◽  
Author(s):  
Lucas Ferreira da Silveira ◽  
Lindino Benedet ◽  
Morjana Signorin ◽  
Rafael Bonanata
Keyword(s):  
Morphological Changes ◽  
Time Frame ◽  
Brazilian Coast ◽  
Coastal System ◽  
Direct Benefits ◽  
Navigation Channel ◽  
Severe Erosion ◽  
Increasing Demand ◽  
Maintenance Dredging ◽  
Benefit Cost

São Francisco do Sul Harbor, located in the Babitonga Bay, Santa Catarina, is one of the main containership harbors in Brazil and has been in operation since 1955. Due to the increasing demand for ships with greater size and draught, the navigation channel was dredged to 10 m depth in 1980 and has been gradually deepened to 13 m in recent years to accommodate Post-Panamax vessels. During the 30 years of dredging operations, more than 10 million m³ of sediments were removed from the coastal system and dumped into an offshore disposal area (about 15 m water depth), whilst the downdrift beach has experienced severe erosion. The downdrift municipality, Itapoá, recently filed a lawsuit against the Port claiming that harbor dredging has caused much of the erosion observed on its beaches. In order to evaluate the downdrift effects of dredging and maintaining the deep draft navigation channel across the ebb shoal of Babitonga Bay, the Delft3D model was used. The model was calibrated and validated with field data (water level and currents, waves and morphological changes). To evaluate channel impacts on adjacent beaches, 10 years morphology change simulations were conducted for pre-dredging scenario and scenarios of the navigation channel dredged at 10 m and 13 m depth, using the dredge and dump tool in Delft3D to maintain the deep draft channel along the simulation. A conceptual model of the sedimentary dynamics of the area was developed utilizing results from numerical modeling and field observations. It was observed in the results that dredging and maintaining the deep draft navigation channel over the last few decades have reduced the amount of sediment bypass by about 13 %. Channel dredging has therefore contributed to the erosion of the adjacent beaches, however other man-made interventions on this coastal system that contributed to the erosion problem were also identified (bay closure and tidal prism changes as well as jetties and other structures built updrift). Thus, it cannot be inferred that all the erosion of the downdrift beaches is due to the dredging activities. To mitigate for erosion effects of channel dredging, beneficial sediment disposal strategies were investigated. Strategies evaluated included beach disposal and ebb-shoal disposal of dredged materials. Beach disposal was the alternative that produced direct benefits to the downdrift beach while ebb-shoal disposal produced benefits that were not directly detected on the beach during the time frame evaluated here. Due to benefit-cost considerations, beach disposal was recommended for maintenance operations where dredging volume is greater than 400.000 m³ (about 50 % of the dredging maintenance operations exceed this threshold). For smaller maintenance dredging events, ebb shoal disposal was recommended. This work is the first of this nature in Brazil driven by legal disputes between downdrift beaches and Port authority and sets the precedent for future beneficial use of dredging materials along the Brazilian coast.

scholarly journals The efficiency of curved jetties in Bay of Santos – SP: numerical modeling

RBRH ◽  
2017 ◽  
Vol 22 (0) ◽  
Author(s):  
Tiago Zenker Gireli ◽  
◽  
Camila Maria Mateus Alves de Souza ◽  
Larissa Bertholdo Nobre ◽  
Patrícia Dalsoglio Garcia
Keyword(s):  
Numerical Modeling ◽  
Latin America ◽  
Hydrodynamic Model ◽  
Physical Modeling ◽  
Considerable Increase ◽  
Access Channel ◽  
Navigation Channel ◽  
Attractive Option ◽  
Maintenance Dredging ◽  
Mike 21

ABSTRACT Nowadays, Port of Santos is the largest in Latin America, and it is undergoing a process of deepening of its access channel and, as its final target, is expected to attain 17 m. A considerable increase in the maintenance dredging volume is expected, particularly for the section of the maritime sandbar that is, currently, only maintained by dredging. Consequently, this study employed numerical modeling to propose an efficient layout for two curved, current-guiding jetties for the transposition of the maritime sandbar of Port of Santos navigation channel, and it’s evaluated their efficiency in maintaining depths throughout the channel. Therefore, it was used only the hydrodynamic model of Mike 21 to compare the results with the physical modeling realized in the same simulation conditionals. The results indicate, in both approaches, the current velocities increased with the proposal jetties. Thus, the accomplished study indicates that the adoption of permanent constructions for transposition of the maritime sandbar of the Port of Santos is clearly feasible and it could constitute a more economically attractive option for maintaining depths of 17 m than the current one.

scholarly journals Impact on a fish assemblage of the maintenance dredging of a navigation channel in a tropical coastal ecosystem

2012 ◽  
Vol 60 (1) ◽  
pp. 25-32 ◽  
Author(s):  
Demarques Ribeiro da Silva Junior ◽  
Sérgio Ricardo Santos ◽  
Marcelo Travassos ◽  
Marcelo Vianna
Keyword(s):  
Fish Assemblage ◽  
Eastern Coast ◽  
Mangrove Forests ◽  
The North ◽  
Navigation Channel ◽  
North Eastern ◽  
High Conservation ◽  
The Subject ◽  
Maintenance Dredging ◽  
Dredge Spoil

Dredging and dredge-spoil disposal are among the major problems in coastal management. Many of the scientific contributions concerning the impacts of this practice are based on the study of sessile organisms and subtropical environments. We evaluated changes in the composition and abundance of a fish assemblage resulting from dredging and sediment disposal at the mouth and in the adjacent waters of the Caravelas River on the north-eastern coast of Brazil. Samples were collected in two directly impacted and three adjacent areas. Differences among stations were not significant, but the dredged site had the least diverse station, as expected. The stations farthest from the directly impacted areas apparently were not influenced by the coastal work, thus suggesting localised effects. The contribution of the present study is particularly important because of the study area's proximity to others that have high conservation value such as mangrove forests and coral reefs, and the relevance of the subject given the continuing dredging activity.

scholarly journals Observations of the Behavior and Distribution of Fish in Relation to the Columbia River Navigation Channel and Channel Maintenance Activities

2001 ◽  
Author(s):  
Thomas J. Carlson ◽  
Gene R. Ploskey ◽  
R. L. Johnson ◽  
Robert P. Mueller ◽  
Mark A. Weiland ◽  
...  
Keyword(s):  
Columbia River ◽  
Navigation Channel ◽  
Channel Maintenance ◽  
Maintenance Activities ◽  
Distribution Of Fish

scholarly journals Sediment Transport and Morphological Response to Nearshore Nourishment Projects on Wave-Dominated Coasts

2021 ◽  
Vol 9 (11) ◽  
pp. 1182
Author(s):  
Cody L. Johnson ◽  
Brian C. McFall ◽  
Douglas R. Krafft ◽  
Mitchell E. Brown
Keyword(s):  
Sediment Transport ◽  
Numerical Experiments ◽  
Decision Makers ◽  
Construction Technique ◽  
Morphological Response ◽  
Nearshore Processes ◽  
Coastal Modeling ◽  
Shoreline Protection ◽  
Navigation Channel ◽  
Channel Maintenance

Nearshore nourishments are constructed for shoreline protection from waves, to provide sediment nourishment to the beach profile, and to beneficially use dredged sediment from navigation channel maintenance. However, it is poorly understood how placement morphology and depth influence nearshore processes operated on wave-dominated coasts. This study investigates the wave fields, sediment transport, and morphological response to three common nearshore nourishment shapes, nearshore berm (elongated bar), undulated nearshore berm, and small discrete mounds, with numerical experiments utilizing the Coastal Modeling System. The nourishments are placed in depths between 3 m and 7 m with a volume of approximately 100,000 m3 and between 400 m and 1000 m in alongshore length. Numerical experiments are carried out in three distinct coastal settings with representative wave climates and geomorphology. Simulation results indicate that shallower, more continuous berms attenuate the most wave energy, while deeper, more diffuse placements retain more sediment. Results from this study improve the understanding of nearshore nourishment shapes and can support decision makers identifying the most appropriate construction technique for future nearshore nourishment projects.

scholarly journals MULTI-INLET MIGRATION MODELING FOR NAVIGATION CHANNEL MANAGEMENT IN TABUSINTAC BAY, EASTERN CANADA

2017 ◽  
pp. 24 ◽  
Author(s):  
Vincent Leys ◽  
Moritz Lehmann
Keyword(s):  
Morphological Evolution ◽  
Barrier Islands ◽  
Tidal Inlets ◽  
Eastern Canada ◽  
Navigation Channel ◽  
Morphological Modeling ◽  
Simulation Results ◽  
Maintenance Dredging ◽  
Air Photo ◽  
Migration Modeling

In New Brunswick, Atlantic Canada, Tabusintac Bay’s multiple tidal inlets meander through narrow barrier islands and are prone to large storm-induced shifts, making navigation hazardous. A multi-evidence assessment comprised of air-photo analysis, field observations and modeling was undertaken to understand the system and recommend sustainable dredging strategies and/or engineering alternatives. The modeling relied on a combination of simple analytical methods for tidal inlet stability, and complex morphological modeling to project the evolution of the nearshore bathymetry. The study recommended reassigning dredging efforts to a new inlet projected to grow and have better stability. Observations two years after the initial modeling effort indicate that the morphological evolution is consistent with the simulation results, and allowed lowered maintenance dredging requirements. This study illustrates how such a multi-evidence assessment of complex coastal dynamics can concretely guide efforts to reduce maintenance dredging and improve safety at sea.

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