Assessing risks of abandoned urban mines in the UNESCO World Heritage City of Ouro Preto, Brazil.

Abstract

The occupation of the Ouro Preto began around 1698, due to the largest gold rush in the world. The wealth that came from gold made it possible to build a city that still maintains a unique architectural ensemble, then Ouro Preto were declared an UNESCO World Heritage Site in 1980. Nevertheless, the mining archaeological sites lacked conservation policies and they became the first targets for urban expansion. In this paper, we disclose an updated database of 148 abandoned mines and 41 shafts, and we aim to create a risk exposure model to select priority areas, which pose the greatest threat to public safety. The ranking model has five major components according to the degree to which people are exposed to the dangers associated with mining sites. To determine the priority areas, the Analytic Hierarchy Model, a method of Multi-Criteria Decision-Making (MCDM) was used with the aid of GIS application. The MCDM highlighted three distinct zones where there are overlap of hazard factors, corresponding to 13% of the initial study area. These zones concentrate 64% of mines and 93% of shafts recorded. Our analysis established sectors of mining vestiges at Ouro Preto that considers safety standards and historic urban environments.