Beachfront Owners Perception of Beach Erosion along an Armored Shoreline in Southern Brazil
Palavras-chave:shore protection, storm, property loss, Rio Grande do Sul.
Brazil has about 8500 km of coastline that is mostly undeveloped. However, the pressure of fast-growing coastal urban centers is already impacting the shore. This paper characterizes shore protection works in Hermenegildo Beach, evaluates their efficiency to protect property against the impact of storm events, and presents the response of beachfront owners to erosion. Hermenegildo is a beach village located 12km north of the border with Uruguay in Rio Grande do Sul, the southernmost state in Brazil. Several factors contribute to beach erosion in Hermenegildo: storm surge, redistribution of wave energy, rising sea level, the presence of an underlying layer of impermeable peat, and human activities. The shoreline is heavily armored with about 61% of beachfront houses protected by revetments (30%), seawalls (18%), or a combination of both (13%). A strong storm struck the Rio Grande do Sul coast in 16 April 1999 and resulted in severe beach erosion and destroyed 22 houses, besides all concrete structures, half of the quarrystone revetments, and 80% of the timber seawalls. Shore protection structures in Hermenegildo are threatened by erosion because: (1) they were built too close to the water, (2) shoreline retreat has been observed, and (3) armoring has reduced beach width. Most of the beachfront owners are aware of the severe beach erosion problem and appear to understand basic coastal dynamics. About 82% of the interviewed beachfront owners lost property due to erosion; 88% subsequently built protection structures to prevent further loss. Surprisingly, 88% of those who did not experience property damage also built defense structures. Armoring is commonly an initiative of beachfront owners who build low-budget structures without consultation by technical experts.