Abstract
In the management of water resources, it is necessary to balance the demands of multiple uses of water and water availability, while enabling use in an environmentally sustainable way. Probability distributions of flow rates are essential tools for assessing water availability. The objectives of this work were to analyze the best probability distribution that conforms to the annual minimum daily average discharge for periods of seven consecutive days (Q7) for 14 stream gauging stations in the Das Velhas River Basin and to identify possible trends in Q7 time series and in bi monthly and annual sets of daily discharges in three key stream gauging stations. The quality of fit was verified by the Anderson-Darling test (A-D). The selection of the models that presented the best fit was done according to the Bayesian Information Criterion (BIC). The Mann-Kendall test was used to verify trends in time series of discharge. In general, better measures of quality of fit were obtained for the probability distributions Gumbel and Rayleigh. Negative trends in discharge distributions were verified in the three stations. For the Várzea da Palma station, the closest to the river mouth, negative and significant trends were found for the Q7 data and daily average discharge for every bimester except the first.
Highlights
Concerns about sustainability of water resources arise frequently in discussions related to environmental and socioeconomic issues at global, regional and local levels
Study Area The study area was the Das Velhas River Basin, located between the latitudes 17°15' S and 20°25' S and longitudes 43°25' W and 44°50' W, in the central region of the state of Minas Gerais, comprising an area of 27,850 km2, which corresponds to 5% of the state area
The probability distributions of Gumbel and Rayleigh were highlighted, since they fit to 8 and 5 stations of 14, respectively, according to the Anderson-Darling test and the possibility to apply the technique of parametric bootstrapping by the @Risk software
Summary
Concerns about sustainability of water resources arise frequently in discussions related to environmental and socioeconomic issues at global, regional and local levels. The exploitation of natural resources, without regard for sustainability, negatively impacts relationships between water availability and demand, limiting regional strategies of social and economic development covering multiple uses, among them public water supply and irrigation. To adequately manage water potential, it is fundamental to know the hydrological characterization of the basin, considering temporal and spatial variability. Knowledge of flow distribution, identifying the probability of maximum and minimum discharges events, is a fundamental aspect of this characterization. In the management of water resources, it is necessary to continually balance water demands and availability, in an environmentally sustainable way. Mello et al (2010) emphasizes the importance of the study of the probability distribution of hydrological variables, since from this knowledge it is possible to determine the appropriate reference values of discharge to estimate regional water availability In the management of water resources, it is necessary to continually balance water demands and availability, in an environmentally sustainable way. Mello et al (2010) emphasizes the importance of the study of the probability distribution of hydrological variables, since from this knowledge it is possible to determine the appropriate reference values of discharge to estimate regional water availability
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