Efetividade de Métodos Estruturais na Construção de Dunas Frontais

Abstract

Frontal dunes are beach natural defenses against the rise of coastal waters and waves during storm surges, promoting a sand storage for beach restoration when erosion problems occurs. The management of coastal areas must include the protection of the existing dunes and the reclaiming of the disturbed ones. The employment of a simple device method in the stabilization of frontal dunes were tested in a pilot area (1 km long of beach line) in Osório county (RS, Brazil). The most effective system employed were simple fences parallel to the coastline and transverse fences to the dominant winds. The material used In the manufacture of these tracks, was dry grass of junco and tiririca plants tied to bamboo's sticks, according D regional workmanship's method. The most favorable year period to the management begins in spring, when strongs winds from NE quadrant increase in frequency and velocity. Meanwhile the more expressive sedimentation rate in the dunes occurs between December and February when the sand supply to the beach is larger. transported through waves of normal incidence and lower energy. This discussed method could be applied in other dune management projects along the Rio Grande do Sul coastline.

Sistemas deposicionais eólicos no Quaternário costeiro do Brasil

“…Os fatores de redução da vegetação podem ser vários, de origem antropogênica ou natural. Os primeiros incluem o impacto de pedestres, animais e veÍculos automotores (Moreira 1988, Tabajara 2000. Entre os fatores naturais, l¡slam-se o avanço de marés de tempestades, a deflação das partes naturalmente menos cobertas por vegetação da duna frontal durante eventos eól¡cos de alta energia, o sepultamento e morte da vegetação por areias trazidas nesses eventos e a eliminação de determinadas espécies de planlas pelo aumento da salinidade (Hesp 1983, Carter 1990, Hesp & Thom 1990, Roy et a/ 1994, Giannini & Santos 1994, Hesp 2000.…”