The rupture of the Fundão mine dam in Mariana municipality, Minas Gerais State, Brazil, spilled the tailings across the Doce River basin. These tailings, composed of residues discarded from the beneficiation of iron ore, are rich in SiO 2 and Al 2 O 3 , as well as some ether amine compounds and NaOH. The aim of this study was to assess the distribution of these sediments, as well as their effect on the riparian zones reached, as compared with preserved sites. Sediment deposition in the river resulted in a morphological change from a meandering profile to a braided aspect. The nutrient and mineral content (P, K, Ca, Mg, Cu, Fe, Mn, Zn, and NO 3 − ) and soil organic matter of the sediments were depleted, whereas NH 4 + , Na, and pH increased. A random presence of ether amines in the sediments was confirmed by quantitative and chromatographic analyses, with concentrations ranging from 0 to 57.8 mg kg −1 ; Na reached values as high as 150 mg kg −1 . The impact of the dam tailings on biota was assessed by estimating total microbial biomass (phospholipid fatty acids), which were depleted in sediments relative to soils from preserved sites. Overall plant mortality, as well as a low resilience capacity, were also observed. Ether amines and Na present in the sediments had a strong toxic effect in the environment. Identification of these substances as the main impact factors will help guide future remediation efforts.

This paper aims to develop a multi-criteria decision analysis (MCDA) tool for rainwater harvesting (RWH) on a university campus in Bogota, Colombia. The specific type of MCDA our research proposes is known as CRIDE (multi-CRIteria DEcision support tool), which allows us to study various methods of RWH. In order to account for uncertainties such as the variability of expert opinions and imprecision stemming from the different criteria required, we have designed this tool to incorporate ELECTRE II and the Monte Carlo method. For this case study we apply a methodology that evaluates the performance of six RWH scenarios. These six input scenarios emerged from an ideal one, wherein all rainwater throughout the campus is successfully harvested and treated until potable. From there, reality sets in: the other five scenarios are varying degrees of deviance from the ideal one, both in terms of water quantity and quality. In regard to collection and treatment we used sustainable urban drainage systems (SUDS). As for the evaluation of each of the scenarios, we outline eight criteria, which include hydraulic performance, compatibility with the University's Master Plan and financial aspects. Our research concludes that CRIDE as a means of support during the decision-making process generates a complete view of possible solutions, in addition to ranking these solutions. The CRIDE-based approach allows for the proposal of a methodology that evaluates the relevance of an established criteria set, using robustness, redundancy and sensitivity.

The design process of urban stormwater systems incorporating BMPs involves more complexity unlike the design of classic drainage systems for which just the technique of pipes is likely to be used. This paper presents a simple decision aid methodology and an associated software (AvDren) concerning urban stormwater systems, devoted to the evaluation and the comparison of drainage scenarios using BMPs according to different technical, sanitary, social environmental and economical aspects. This kind of tool is particularly interesting so as to help the decision makers to select the appropriate alternative and to plan the investments especially for developing countries, with important sanitary problems and severe budget restrictions.

Infiltration systems are widely used to manage stormwater in urban areas but questions about their long term sustainability need to be addressed. The possible pollution of the groundwater and the concentration of pollutant trapped in the soil are of major interest. This article focuses on the concentration of heavy metals found in the top layer of an infiltration basin. Two sampling campaigns have been undertaken 10 months apart and 200 samples were collected and analysed for lead (Pb), zinc (Zn) and copper (Cu). High concentrations were measured at the surface of the system; pollutant build up over time is clearly evident, especially in the lower lying areas, as well as higher concentrations in the oldest part of the system. Finally, the total mass of heavy metals trapped in the top layer of the systems are evaluated.

Nowadays, stormwater infiltration systems are frequently used because of their ability to reduce flows and volumes in downstream sewers, decrease overflows in surface waters and make it possible to recharge groundwater. Moreover, they come in various forms with different uses. Despite these advantages the long term sustainability of these systems is questionable and their real performances have to be assessed taking into account various and sometimes conflicting aspects. To address this problem a decision support system is proposed. It is based on a multicriteria method built to help managers to evaluate the performance of an existing infiltration system at different stages of its lifespan and identify whether it performs correctly or not, according to environmental, socio-economic, technical and sanitary aspects. The paper presents successively: the performance indicators and the way they were built, the multicriteria method to identify if the system works properly and a case study.