EROSIVE EVIDENCES IN “SANTA CATARINA” ISLAND BEACHES

Proceedings of the 12th Biennial Coastal Zone Conference
Cleveland, OH
July 15-19, 2001
EROSIVE EVIDENCES IN “SANTA CATARINA”
ISLAND BEACHES, SC, BRAZIL
Norberto Olmiro Horn Filho, Universidade Federal de Santa Catarina*
Paulo Cesar Leal, Universidade Federal de Santa Catarina*
João Sérgio de Oliveira, Universidade Federal de Santa Catarina*
Fernando Luis Diehl, Universidade do Vale do Itajaí*
Keywords: Coastal erosion, beach, “Santa Catarina” island, Brazil
INTRODUCTION
Beaches constitute representative geomorphologic feature of the coastal environment.
Several works have been accomplished in beaches along of world shorelines, focalizing
different geological aspects related to morphology, sedimentology and morphodynamic,
objectifing to study the processes, causes and consequences of the coastal erosion.
Coastal erosion is associated to several causes and processes, compreeending:
oceanographic influence of coastal hydrodynamics (waves, currents, tides, winds);
relative sea- level changes; climactic oscillations during the Quaternary; anthropic
interference along the coast and decreasing of sediments originated of continental areas.
These factors produce relative shortage of sediments along of coastlines.
Erosive evidences are usual in brazilian beaches, associated to natural or anthropic origin,
resulting in most of the situations in consequent desestabilization of the fragile balance of
theses ecosystems.
The beaches have been studied by brazilian researchers aiming elucidate the coastal
erosive processes, identifying their causes and consequences. In “Santa Catarina” island,
the studies are still recent, detacching the results obtained from Santos (1995), Abreu de
Castilhos (1995), Diehl (1997), Nunes (1997), Leal et al. (1998), Faraco (1998), Horn
Filho et al. (1999b) and Torronteguy and Horn Filho (2000), which indicate erosive
evidences in “Armação, Barra da Lagoa, Campeche, Canasvieiras, Daniela, Forte,
Ingleses, Joaquina and Moçambique” beaches.
LOCALIZATION OF THE STUDIED AREA
The “Santa Catarina” island is located between 27º22’45” and 27º50’10” south latitudes
and 48º21’37” and 48º34’49” west longitudes, littoral Central of the “Santa Catarina”
state at southeast brazilian coast. Presents along of 174.3km of total perimeter 117 sandy
beaches. Its littoral is compartmented according geomorphologic and sedimentologic
aspects in six coasts: Northwest, North, Northeast, Southeast, South and Southwest (Horn
Filho et al., 1999a):
1
Proceedings of the 12th Biennial Coastal Zone Conference
Cleveland, OH
July 15-19, 2001
COASTAL EROSION IN “SANTA CATARINA” ISLAND
Along of perimeter of the island, are evidenced several erosion focus, originated from
natural and anthropic processes. According to their localization, granulometry, shape,
morphology, occupation, energy level and oceanographical parameters, the beaches
generate different answers in their profiles and sectors.
The areas where the erosion points are more perma nent or temporary, are associated to
beaches exposed to higher energy, mainly in coasts faced to Atlantic ocean and
represented predominantely by North, Northeast and Southeast coasts. Have been pointed
out erosion evidences in “Daniela, Forte, Canasvieiras, Ponta das Canas, Ingleses, Brava,
Moçambique, Barra da Lagoa, Galheta, Mole, Joaquina, Campeche and Armação”
beaches.
The beaches of North coast (“Canasvieiras, Ingleses, Forte and Ponta das Canas”),
present the erosion allied dominately to disordered occupation above backshore,
decreasing consequentely the sediment volume resulting sedimentar deficit in beach
profiles.
Relationed to beaches of Northeast and Southeast coasts, exposed to higher energy, the
dominant erosive agents are associated to natural causes, observed in “Moçambique,
Mole, Joaquina, Campeche and Armação” beaches. These causes are allied to cold front
passages, decreasing of sediments, incident swell, longshore currents and batymetry of
the foreshore and inner continental shelf. The anthropic causes are also considered like
secondary factor, mainly in beach extremities, e.g., “Barra da Lagoa, Joaquina and
Armação” beaches. The human influence is related to predatorious occupation of the
coastal environment, taking up the sectors of backshore, foredune and coastal plain,
shaping several edification types like residences, resorts, hotels, public eating houses and
engineering structures, which do harm to the beaches.
During winter and fall storm conditions, the natural processes are aggravated mainly
under syzygy tide, lifting the tide level and consequentely reaching highest sectors of the
beach profile. This situation is common along “Santa Catarina” island littoral during may
to september months.
Integrated studies are primordial to the monitoring of the observed focus, attempting
possibly the recuperation and recognition of new hazard areas.
REFERENCES
ABREU DE CASTILHOS, J. 1995. Estudo evolutivo-sedimentológico e
morfodinâmico da praia da Armação, ilha de Santa Catarina- SC. Florianópolis.
179p. Dissertação de Mestrado. Curso de Pós-Graduação em Geociências,
Universidade Federal de Santa Catarina.
DIEHL, L. F. 1997. Aspectos geoevolutivos, morfodinâmicos e ambientais do pontal
da Daniela, ilha de Santa Catarina, Brasil. Florianópolis.132p. Dissertação de
2
Proceedings of the 12th Biennial Coastal Zone Conference
Cleveland, OH
July 15-19, 2001
Mestrado, Programa de Pós-Graduação em Geografia, Universidade Federal de Santa
Catarina.
FARACO, K. R. 1998. Estudo morfodinâmico e granulométrico da praia dos Ingleses,
ilha de Santa Catarina, SC. Florianópolis. 68p. Monografia de Conclusão de Curso.
Curso de Bacharelado em Geografia. Universidade Federal de Santa Catarina.
HORN FILHO, N. O.; OLIVEIRA, J. S. de; LEAL, P. C. 1999a. Mapping the Santa
Catarina island’s coast, Santa Catarina, southeastern, Brazil. In: COASTAL ZONE 99.
San Diego, 1999. Abstracts: pp.401-403.
HORN FILHO, N. O.; OLIVEIRA, J. S. de; & LEAL, P. C. 1999b. Evidências erosivas
na praia de Canasvieiras, ilha de Santa Catarina, SC, Brasil. In: SEMANA NACIONAL
DE OCEANOGRAFIA, 12., Rio de Janeiro, 1999. Resumos Expandidos...Rio de Janeiro:
AOCEANO. pp. 56-59.
LEAL, P. C.; HORN FILHO, N. O. & OLIVEIRA, J. S. de. 1998. Evidências erosivas do
setor Centro-Norte da praia de Moçambique, ilha de Santa Catarina, Santa Catarina,
Brasil. In: SIMPÓSIO NACIONAL DE GEOMORFOLOGIA, 2., Florianópolis, 1998.
Resumos Expandidos. Florianópolis: UGB/UFSC. Geosul, 27:229-231.
NUNES, M. G. 1997. Estudo evolutivo, sedimentológico e morfodinâmico da praia do
Forte – ilha de Santa Catarina. Florianópolis. 72p. Monografia de Conclusão de Curso,
Curso de Bacharelado em Geografia, Departamento de Geociências, Universidade
Federal de Santa Catarina.
SANTOS, C. R. dos 1995. Inter-relação entre a dinâmica da vegetação pioneira e os
padrões morfo-sedimentológicos sazonais da praia da Joaquina, ilha de Santa Catarina,
Brasil. 207p. Dissertação de Mestrado. Curso de Pós-Graduação em Geociências,
Universidade Federal de Santa Catarina.
TORRONTEGUY, M.de C. & HORN FILHO, N.O. 2000. Influência da ilha do
Campeche no comportamento morfodinâmico do arco praial Joaquina - Morro das
Pedras, ilha de Santa Catarina, SC, Brasil. In: SEMANA NACIONAL DE
OCEANOGRAFIA, 13., Itajaí, 2000. Anais.. Itajaí. p.90-92.
* Institutions of the Brazilian Marine Geology and Geophysics Program - PGGM
Norberto Olmiro Horn Filho
Departamento de Geociências
Universidade Federal de Santa Catarina - UFSC
PO Box 476
Florianópolis, Santa Catarina, Brasil 88040-900
(48) 331-9664
[email protected]
3