Download full issue - PanamJAS

180D. MUEHEPaulo, Paranaguá and Guaratuba in Paraná and SãoFrancisco do Sul in Santa Catarina. From the northof Santa Catarina to the south of Santa CatarinaIsland the coastline becomes irregular with outcropsof the crystalline basement and small coastal plains.Southward of Santa Catarina Island and cape SantaMarta, in Santa Catarina, the coastline is formed bya sequence of beaches limited by rocky promontorieswith wide coastal plains and lagoons.Longshore sediment transport tends to bedirected to the north. The occurrence of extratropicalcyclones with strong winds, heavy rain andhigh waves has been a main threat and seems toincrease in frequency. Associated to an increase intemperature of the ocean water their occurrence willincrease and may also affect the coastline up to Riode Janeiro.Modifications of the coastline due to erosionare, in São Paulo, usually isolated and associatedwith natural or artificial obstacles that interrupt theflow of sediments (Tessler et al. 2006).In Paraná, the most significant modifycationsof the coastline occur on the estuarine outlets(e.g., the Superagui channel, Peças island, Mel island,Pontal do Sul, Ponta de Caiobá and Guaratuba).These modifications include both retreat andadvance of the shoreline and occurred on the orderof hundreds of meters in less than a decade (Anguloet al. 2006). The ocean coastline is presently stable.Areas most impacted by erosion are the beach resortsof Flamengo and Riviera and the central beachof Matinhos, restored through beach nourishment.In Santa Catarina, investigations were concentratedon the central north coast (Klein et al.2006) and on the island of Santa Catarina (Horn2006). On the continental coast, the risks associatedwith coastal erosion result from inappropriate landuse and frequent storms. The most critical points arelocated in Barra Velha, Piçarras and Penha. These a-reas are experiencing medium-intensity erosion, andBombinhas is experiencing low-intensity erosion.On the island of Santa Catarina, erosion is occurringthroughout the ocean coast. The greatest risk is tothe urban areas on the north coast of the island (e.g.,beaches of Canasvieiras, Cachoeira and the Ingleses)and on the northwest coast in the Barra da Lagoa.Urbanized areas on the east and south coastwith medium to high risk of erosion include Campeche,Armação and Pântano do Sul (Horn 2006).Areas with the greatest risk of flooding areidentified by Tessler (2008) and include theestuarine region of São Vicente and Santos in SãoPaulo, Paranaguá at the Bay of Paranaguá in Paraná,and in Santa Catarina at the southern shore of theBabitonga bay, at the estuary of the Itajaí-Açu Riverand at the localities of Palhoça and São José on thewest shore of the South Bay and Florianópolis at themargins of the North and South Bay.Strohaecker (2008) call attention to the highrate of population growth in the urban areas extendinghundreds of kilometers along the coastline.The Sandy Coast of Multiple Barriers of RioGrande do SulFrom cape Santa Marta to Chui, at theborder between Brazil and Uruguay, the coastline isformed by a long, wide, fine grained and monotonousbeach in front of a multiple barrier-lagoonsystem, with the widest lagoons represented by thePatos and Mirim Lagoons. Active dune fields developon top of the coastal barriers with dominant sandtransport to southwest. Storm surges are frequentlysubmitting the shoreline to a harsh wave climate.The beach shows a high morphodynamicmobility alternating between long stretches of retreatand advance (Toldo et al. 2006) and reversal of thistrend over time (Esteves 2008). This mobility hasbeen in most cases limited to the beach without adefinite retreat of the backshore. Very localizedsegments of coastal erosion were described byCalliari et al. (1998) and Speranski & Calliari (2006)and were related to wave convergence in Mostardas,to the south of the Mostardas lighthouse, betweenBojurú and Estreito and at a small segment nearCassino and in the far south near Chuí.The distribution of population along thecoast is low and mostly concentrated in urbancenters of second homes that attract nearly 100,000visitors during the summer. The main urban center islocated at the estuary near the mouth of the Lagoados Patos in Rio Grande. With about 200,000inhabitants the city is located in low laying areas ofthe coastal plain and present the highest risk offlooding of the entire Brazilian coast (Tessler 2008).The port of Rio Grande is one of the most importantin the country because its depth, its favorablelocation in relation to MERCOSUL countries andthe presence of important industrial and petrochemicalcomplexes.Final ConsiderationsThe Brazilian shoreline is experiencingerosion along the entire coast, but the erosion isirregularly distributed and often associated withriver outlets. Large segments of the coast are formedby sedimentary cliffs in areas of low occupationwhere erosion is slow. On beaches the erosionbecomes a risk when buildings are constructed toclose to the shore. Numerous low-lying coastalplains formed by the sedimentary fill of old lagoonsPan-American Journal of Aquatic Sciences (2010) 5(2): 173-183