Suchergebnisse

A new statistical approach for preliminary risk evaluation of breakage in tailings dam is presented and illustrated by a case study regarding the Mediterranean region. The objective of the proposed method is to establish an empirical scale of risk, from which guidelines for prioritizing the collection of further specific information can be derived. The method relies on a historical database containing, in essence, two sets of qualitative data: the first set concerns the variables that are observable before the disaster (e.g., type and size of the dam, its location, and state of activity), and the second refers to the consequences of the disaster (e.g., failure type, sludge characteristics, fatalities categorization, and downstream range of damage). Based on a modified form of correspondence analysis, where the second set of attributes are projected as "supplementary variables" onto the axes provided by the eigenvalue decomposition of the matrix referring to the first set, a "qualitative regression" is performed, relating the variables to be predicted (contained in the second set) with the "predictors" (the observable variables). On the grounds of the previously derived relationship, the risk of breakage in a new case can be evaluated, given observable variables. The method was applied in a case study regarding a set of 13 test sites where the ranking of risk obtained was validated by expert knowledge. Once validated, the procedure was included in the final output of the e‐EcoRisk UE project (A Regional Enterprise Network Decision‐Support System for Environmental Risk and Disaster Management of Large‐Scale Industrial Spills), allowing for a dynamic historical database updating and providing a prompt rough risk evaluation for a new case. The aim of this section of the global project is to provide a quantified context where failure cases occurred in the past for supporting analogue reasoning in preventing similar situations.

In regions with semi-arid characteristics, groundwater is a precious source of water supply, mainly from alluvium, due to the decent quality of its waters. However, the sandy texture favors vulnerability, and the infiltration and percolation of fluids increase the risk of contamination of the aquifer in the presence of polluting sources. The population's knowledge about these problems is still ephemeral, which can lead to the consumption of contaminated water, putting health at risk. Thus, research was conducted in the municipality of Russas – Ceará, to study the quality of groundwater, the possible polluting sources in the urban area, and assess the possible risks to human health. First, technical visits for reconnaissance and survey of information were conducted, such as possible polluting sources and situations of existing wells. The selection of wells to collect water followed criteria of proximity to polluting sources, well conditions, and, mainly, those linked to the use of water for human consumption. The result showed that 43% of the samples are above the limits proved by Brazilian legislation for turbidity, total hardness, TDS, sodium, chloride, and nitrate, while the others are withinthe standard. Concerning chlorides and nitrates, the concentrations show there is possibly a relationship with anthropic contaminants(agricultural area; domestic effluents) for the aquifer recharge areas and condition common problems to human health. Therefore, it is of paramount importance to continue research in Medical Geology that will enable the monitoring and future management of water quality of groundwater for the population.