Extreme Events Assessment Methodology Coupling Debris Flow, Flooding and Tidal Levels in the Coastal Floodplain of the S&amp;amp;atilde;o Paulo North Coast (Brazil)

Rafael De Oliveira Sakai,Paolo Alfredini,Wilson Cabral De Sousa Júnior,Luca Magni,Diego Lourenço Cartacho,Alessandro Pezzoli,Maurizio Rosso,Emilia Arasaki

doi:10.4236/ijg.2013.45b006

Abstract

The North Coastal Region of the State of Sao Paulo, which comprises the Municipalities of Caraguatatuba, Sao Sebastiao, Ilhabela and Ubatuba, is one of the most prone to flooding and debris flow deposition Brazilian areas, owing to hydrological extreme rainfall events usually coupled with extreme tidal levels. This risk is also high due to human lives and material assets, with increasing population rates and the establishment of large companies such as the Oil industry, with reduced defense/prevention measures and works. The catastrophic scenario of the city of Caraguatatuba, in March 1967, resulting from one of the most serious natural disasters in Brazil, fosters discussions about probabilities of heavy rainfall-caused events and rise in the sea level in coastal areas. Hence, this research is a consequence of this reality. The research is founded on an innovative methodology based on the analysis of past data of rainfall and tidal stations, complemented with debris flow registers in the region of the north coastal zone of the State of Sao Paulo (Brazil). The anaysis developed involved the meteorological, hydraulic, geotechnical and statistical knowledge areas. Practical results are intended to be used for urban planning, designs of macro-drainage, fluvial, maritime projects and debris flow retention structures. These practical applications will then associate the probability of occurrence of certain types of heavy rainfall-caused events such as flooding or debris flow coupled with a corresponding increase in tidal levels.

Highlights

This research is inserted into an area of Civil Engineering, in the interface between Maritime Hydraulics, Hydrology and Geotechnics.Our main objective was to evaluate heavy rainfallcaused events combined with tidal levels, and to obtain practical results applicable to urban planning fluvial and maritime projects and debris flow retention structures in the Santo Antonio River Basin (Figure 1), located in the city of Caraguatatuba, on the North Coast of São Paulo/Brazil
The north coastal region of São Paulo is known for its orographic rainfall, caused by moisture fronts from the Atlantic Ocean; when they collide with the mountain range of Serra do Mar, there is a precipitation on the coastal towns
The methodology described in this item was adapted from HIDROCONSULT [6], which conducted a similar study for Cubatão city, which is located in the central coast of the State of São Paulo

Summary

Introduction

This research is inserted into an area of Civil Engineering, in the interface between Maritime Hydraulics (tidal levels and hyperconcentrated flows), Hydrology (rainfall) and Geotechnics (percolation and landslides).Our main objective was to evaluate heavy rainfallcaused events combined with tidal levels, and to obtain practical results applicable to urban planning fluvial and maritime projects and debris flow retention structures in the Santo Antonio River Basin (Figure 1), located in the city of Caraguatatuba, on the North Coast of São Paulo/Brazil. This research is inserted into an area of Civil Engineering, in the interface between Maritime Hydraulics (tidal levels and hyperconcentrated flows), Hydrology (rainfall) and Geotechnics (percolation and landslides). Our main objective was to evaluate heavy rainfallcaused events combined with tidal levels, and to obtain practical results applicable to urban planning fluvial and maritime projects and debris flow retention structures in the Santo Antonio River Basin (Figure 1), located in the city of Caraguatatuba, on the North Coast of São Paulo. The north coastal region of São Paulo is known for its orographic rainfall, caused by moisture fronts from the Atlantic Ocean; when they collide with the mountain range of Serra do Mar, there is a precipitation on the coastal towns. According to Brigatti and Sant’Anna Neto [1], the Northern Coast of São Paulo, for its own natural characteristics and the recent economic dynamics, is characterized as an area where studies

Methods

Results

Conclusion