EFEITO OROGRÁFICO NA ILHA DE SÃO SEBASTIÃO (ILHABELA – SP)

Abstract

This article aims at assessing, in the relationship between rain versus relief, the occurrence of orographic precipitation on the windward side of the Island of São Sebastião (Ilhabela - SP). Throughout the Hydrologic Year 2004 - 2005 rainfall data were collected monthly, through the installation of six experimental rain gauges in Castelhanos Road - guidance W - E, with 22 km and maximum altitude of 690m, at different altitudes. The data were descriptive statistics and their synthesis led essentially to three results: 1) more than a half or 60.1% of the total rainfall collected was precipitated on the exposed side of the SE sector flows (windward) confirming the importance of the relief in its distribution; 2) rain shadow description through the reduction of rainfall in the lee of the island, where the values collected were 20% lower than the opposite side, and 3) identification of orographic rain at 600m altitude (P7), where the collected values were invariably higher than the others, around 30% higher, exceeding 4000 mm per year and reaching a total monthly of 708.5 mm in March 2005.

Keywords

• Ilha
• Relevo
• Precipitação
• Chuva orográfica
• Sombra de chuva