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This paper presents the results of the planform stability classification for the headland-bay beaches of the State of Santa Catarina and of the Northern Coast of São Paulo, based on the application of the Parabolic Bay-Shape Equation (PBSE) to aerial images of the beaches, using the software MEPBAY®. For this purpose, georeferenced mosaics of the QuickBird2® satellite imagery (for the State of Santa Catarina) and vertical aerial photographs (for the northern coast of São Paulo State) were used. Headland-bay beach planform stability can be classified as: (1) in static equilibrium, (2) in dynamic equilibrium, (3) unstable or (4) in a state of natural beach reshaping. Static equilibrium beaches are the most frequent along the coast of the State of Santa Catarina and the Northern Shore of São Paulo, notably along the most rugged sectors of the coast and those with experiencing lower fluvial discharge. By comparison, dynamic equilibrium beaches occur primarily on the less rugged sectors of the coast and along regions with higher fluvial discharge. Beaches in a state of natural beach reshaping have only been found in SC, associated with stabilized estuarine inlets or port breakwaters. However, it is not possible to classify any of these beaches as unstable because only one set of images was used. No clear relation was observed between a beach's planform stability and other classification factors, such as morphodynamics or orientation.

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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.

The coastline of Panama City Beach, Florida (FL) has been stricken by several hurricanes during the last decades, especially after 1995. In 1998, beach nourishment projects started being implemented to address the impacts of the hurricanes on the coast. Sources of sand for that purpose are commonly from borrow areas located just offshore of the nourishment site. Impacts of these nearshore dredge pits on adjacent coasts will depend on incident wave conditions, nourishment sediment characteristics and some features of the borrow pit (distance from the shore, depth of cut, cross-shore extent, alongshore extent and orientation - Bender & Dean, 2003; Benedet & List, 2008). The practical goal of the current study was to mitigate for the negative potential effects by discovering the less impactful design of dredge pit geometries on the Borrow Area S1 in Bay County-FL. Five different cut widths and excavation depths within the permitted limits were herein evaluated. Evaluation of morphological impacts on adjacent beaches was carried with the processed-based morphodynamic model Delft3D, calibrated and simulated for a period of 13 years. Results were evaluated in terms of beach volume changes compared against a baseline simulation (no action).Switching from Alternative 1 (6,260,000 m³) to Alternative 2 (5,380,000 m³) does not result in a substantial reduction of the borrow area’s projected impact. The cut depth is still deep, and the surface area is unchanged. Alternative 3 (3,555,000 m³) is able to provide more substantial reductions in the borrow area’s impact. By reducing the acreage of the borrow area and switching to a uniform cut depth, the projected impact of the borrow area decreases 39% for 1.56 km along the downdrift beach. Under Alternatives 4 (3,060,000 m³) and 5 (2,755,000 m³), the impacts of the borrow area are projected to be less than 3.75 m³/m/yr. While both alternatives are viable, Alternative 5 minimizes potential impacts, and has a uniform cut depth and a volume that still satisfies the project’s requirements. Given these considerations, Alternative 5 is the preferred alternative. Additionally, all the alternatives increase the net-accretion along 6.5 km of Shell Island between 0.25 to 1 m³/lm/yr., a valuable side effect in a region with high net erosion. By conducting various simulations an optimal borrow area design has been identified that reduces its effects on the adjacent beaches.