Rosângela Francisca de Paula Vitor Marques

Distribuição de probabilidades para precipitação máxima diária na Bacia Hidrográfica do Rio Verde, Minas Gerais

Estimativas probabilisticas de eventos extremos sao de grande relevância para o planejamento das atividades humanas. As distribuicoes de probabilidade possibilitam a estimativa de eventos de precipitacao maxima diaria anual associados as suas frequencias de ocorrencia. Objetivou-se, com este trabalho, identificar, dentre as distribuicoes Gumbel, Gama a 2 parâmetros e Generalizada de Valores Extremos (GEV), qual a mais indicada para aplicacao as series historicas de precipitacao maxima diaria anual na bacia hidrografica do rio Verde, no Sul de Minas Gerais. Os parâmetros de cada distribuicao foram estimados pelos metodos dos momentos, maxima verossimilhanca e momentos-L. Para tal, foram empregadas, neste estudo, oito estacoes pluviometricas com series historicas de, no minimo, 20 anos de dados, distribuidas pela bacia hidrografica. Pelos testes de adequacao de Kolmogorov-Smirnov, Qui-Quadrado, Anderson Darling e Filliben, a distribuicao Gumbel, estimada pelos tres metodos, obteve os ajustes menos adequados. A distribuicao GEV, pelo metodo dos momentos-L, foi a mais adequada para analise probabilistica de precipitacao maxima diaria na Bacia Hidrografica do Rio Verde, devendo ser priorizada para planejamentos na regiao.

Performance of the probability distribution models applied to heavy rainfall daily events

Probabilistic studies of hydrological variables, such as heavy rainfall daily events, constitute an important tool to support the planning and management of water resources, especially for the design of hydraulic structures and erosive rainfall potential. In this context, we aimed to analyze the performance of three probability distribution models (GEV, Gumbel and Gamma two parameter), whose parameters were adjusted by the Moments Method (MM), Maximum Likelihood (ML) and L - Moments (LM). These models were adjusted to the frequencies from long-term of maximum daily rainfall of 8 rain gauges located in Minas Gerais state. To indicate and discuss the performance of the probability distribution models, it was applied, firstly, the non-parametric Filliben test, and in addition, when differences were unidentified, Anderson-Darlling and Chi-Squared tests were also applied. The Gumbel probability distribution model showed a better adjustment for 87.5% of the cases. Among the assessed probability distribution models, GEV fitted by LM method has been adequate for all studied rain gauges and can be recommended. Considering the number of adequate cases, MM and LM methods had better performance than ML method, presenting, respectively, 83% and 79.2% of adequate cases.

Impacts of urban solid waste disposal on the quality of surface water in three cities of Minas Gerais - Brazil

The environmental impact of three different urban solid waste facilities (USWF) on the quality of the surface water. The studied areas were the Campo Belo sanitary landfill (Varoes River), the controlled landfill of Santo Antonio do Amparo (Fabiano River), and the closed dump of Eloi Mendes (Mutuca River), which are cities located in southern Minas Gerais state, Brazil were evaluated. At each sampling point water samples were collected at five occasions in the raining season (October - March) and in the dry season (April - June) at three sampling points: (P1) upstream the solid waste facility, (P2) downstream nearby the point of influx from the sewage treatment plant in the sanitary landfill, or at the drainage point from the surface flow of the dump and controlled landfill, and (P3) downstream the solid waste facility. Physicochemical and bacteriological analyses were performed, and the results were analyzed based on descriptive statistics. The data were also compared with reference values from the National Environmental Council (CONAMA) Resolution 357/2005 and were used to calculate the water quality index (WQI). It was not possible to detect a significant effect of the solid waste facility on the water quality indicators. The water conditions were unsatisfactory due to violations of the concentrations of phosphorus, ammonia, fecal coliform, and the biochemical oxygen demand/chemical oxygen demand ratio (BOD/COD), probably related to other uses along the drainage area upstream the solid waste facility. These conditions were more critical in the Mutuca river, where the WQI was classified as bad during the entire period at all sampling points.

Encapsulation of Natural Flavors in Cyclodextrins: Free Volume Studies by PALS

Positron annihilation lifetime spectroscopy (PALS) is used to study the free-volume in β-cyclodextrin (CD) with the encapsulation of two different essential oils: garlic (Allium sativum) and marjoram (Origanum majorana). The data reveal the presence of a long lifetime component related to the o-Ps. It is observed that the addition of garlic (or marjoram) oil to β-CD results in a decrease of the o-Ps lifetime which was ascribed to a reduction of the free volume holes from 83.6 to 67.7 Å3 (79.1 to 72.6 Å3). Different mechanisms for the encapsulation of garlic and marjoram oils in β-CD are suggested by the PALS parameters.