Fluvial Erosion Risk Analysis: An Amazon Study Case

Abstract

In the Amazon region, there are more than 26.000 people living in areas at risk of fluvial erosion processes. In addition to the large number of people impacted, studies have shown that the erosion patterns identified on the margins of mega rivers in the Amazon region are distinct due to the fact they are related the mass movement leading to great soil displacement known as ‘Terras Caidas’. In this context, this study aims to evaluate quantitatively the degrees of risk in areas subject to fluvial erosion in three communities: Itanduba, São Braz, and Fátima de Urucurituba. The methods include hazard attributes, as well as vulnerability aspects, through the Analytic Hierarchy Process (AHP). A multitemporal analysis were made to validated the marginal erosion at the studied areas. The results indicated a high risk of fluvial erosion on these areas. The local families lives under high and very high social vulnerability in conditions with little infrastructure and very close to the susceptible erosive riverbank. The riverbank is composed of poorly consolidated sediments, show instability indicators, and are usually associated to drainages with flow rates above 100.000m3/s. The results and methodology brings an important contribuition to territorial planning of the region.