Comparative analysis between the floods and the rate of urbanization in the Ribeira Valley, São Paulo - Brazil
Abstract
The aim of this paper is to analyze the occurrence of floods facing the rate of urbanization in the Ribeira Valley. The Ribeira Valley is located on the basin of Ribeira de Iguape River in eastern Paraná and southeastern São Paulo state in Brazil. The region has been considered one of the most important international conservation priorities by agencies such as the International Union for the Conservation of Nature (IUCN), and the UNESCO/MAB Program. This region has a history of recurrent floods, causing huge financial losses particularly to the poorest people, including casualties as well as material losses. This study analyzed three flood events that occurred in January 1995, January 1997 and February-March 1998, reaching the towns of Eldorado, Ribeira and Sete Barras. To determine the affected areas, the researchers used the shapes (digital data) obtained from the Geographic Information System of Ribeira de Iguape River Basin which is maintained by the Ribeira de Iguape River Basin and South Seashore Committee. The SPRING was the processing tool used for data manipulation. Additionally we used rainfall data, flow and water level elevation for the years 1983, 1995, 1997, 1998 and 2011. The results show that in January 1997 there happened the largest flood area across the three cities and this effect coincides with the highest levels of rainfall and flow. The second largest flood happened in January 1995 and the smallest one was in February-March 1998. Another important aspect to be noted is that all floods affected a large floodplain in both rural and urban areas. It was also found a direct relationship between the rate of urbanization and the area affected by the floods. The results show that the larger the area of urbanization, the larger the flooded area. It was also verified in the precipitation climatology that most extreme events occurred in 1983 and 2011. Specifically the 2011 event occurred during dry season bringing the whole region to a state of emergency, reaching 17 municipalities. The Ribeira Valley reached its flood peak of 13.45 m on 08/02/2011 in Eldorado with a total of 27,931 people affected. Since the urban areas for the cities studied are vulnerable to flood risk, it is necessary a thorough registration of the worst event reaching the whole area and the people affected in order to find the best way to mitigate the impacts of this natural disaster.
- Publication:
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AGU Spring Meeting Abstracts
- Pub Date:
- May 2013
- Bibcode:
- 2013AGUSMNH51D..06F
- Keywords:
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- 0468 BIOGEOSCIENCES / Natural hazards