Márcio Baptista

Multicriteria decision-aid method to evaluate the performance of stormwater infiltration systems over the time

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.

The use of tritium content as an indicator of the groundwater contamination by sanitary landfills leachates in the region of Belo Horizonte City, Brazil

Tritium content in the leachate of sanitary landfills, in concentrations well above those observed in global precipitation, can be used as a tracer for the evaluation of the contamination of groundwater in piezometers of the landfills and in neighbouring tubular wells. This possibility was first investigated in Brazil for sanitary landfills in the region of Belo Horizonte City. Tritium levels together with the content of metals present in water and the measurement of soil electrical conductivity, proved to be valuable for these studies and also as a tracer for hydrodynamic studies of the surface water in the Ressaca creek.

Detecção de tendências para eventos extremos de precipitação na Região Metropolitana de Belo Horizonte a partir de métodos estatísticos

Extreme weather events have emerged as one of the main manifestations of climate change, being that the mitigation of the elapsed impacts demand studies of the magnitude and frequency of their occurrence. This study aims to identify the trends of extreme precipitation events in the Metropolitan Region of Belo Horizonte, especially concerning their frequency. The trends of precipitation were studied with especial regard to the indices set by ETCCDMI (Expert Team on Climate Change Detection Monitoring and Indices), including time series of annual number of rainy days above a certain threshold recorded at fourteen rainfall gauging stations. One stage of this study consisted in surveying the flood occurrence in the area, besides analyzing the precipitation data corresponding to date of flood occurrences, in order to establish a threshold value beyond which an event would entail potential impacts. No regional index pattern could be set based on such results, although the rainfall station located in the city of Belo Horizonte reported a statistically significant increase in daily precipitation events above 10, 20, 30 and 40 mm, in maximum precipitation recorded over five consecutive days, in daily intensity, and in total annual precipitation. Abrupt changes in rainfall series were also recorded. The results have indicated that the city may be potentially impacted by extreme rainfall increase, probably associated to changes in temperatures on regional and local scales.

Méthodologie multicritère d'aide à la décision pour les systèmes d'infiltration des eaux pluviales: Méthodes et exemples

ABSTRACT Infiltration systems are frequently used as an option to manage urban storm drainage. Despite their advantages, long-term sustainability of infiltration systems is not certain. The use of these systems raises numerous questions; the main question is about the real performances of these techniques, in terms of the services they have to return in the cities, where the natural phenomena and human behaviours are coupled. Attempting to answer these questions a research aiming the evaluation of infiltration systems performances, concerning their sustainability, was performed. In this article we present the construction steps of a decision aid methodology to evaluate infiltration systems in the actual state of the research.