Avaliação da influência da mudança de variáveis de projeto de barragens sobre as alterações hidrológicas e componentes do regime de vazão natural

Abstract

Dams provide benefits to the society through hydro power generation and when they supply cities with water, for example. However they also have negative impacts, such as hydrological changes in the long, medium and short term. Once the hydrological impacts can be predictors of changes in aquatic biota, is extremely important that studies of such changes caused by dams are made still in the design phase. This paper presents an assessment of how the change in dam design variables influence the hydrological changes and the five components of the natural flow regime (magnitude, frequency, duration, time of occurrence and rate of change).For this, changes imposed by dams on a perennial river were simulated. In possession of the modeling data these changes were evaluated and classified with the Indicators of Hydrological Alteration (IHA) and the Hydrological Regime Alteration Dundee Method (DHRAM).And then a sensitivity analysis was performed using statistical concepts of Factorial Design. The hydrological changes affected in different ways and with different degrees each group of hydrological parameters of the IHA. The classification of DHRAM indicated that the storage capacity directly influenced the impact of hydrologic alteration. The sensitivity analysis suggests that the demand and the remaining flow affect the hydrological changes and the natural flow of components. The obtained results indicate that the study of hydrological changes can be made even in the design phase to select a project alternative that takes into account, among other issues involved (eg, technical and economic factors), also the least impact on the hydrological regime of a river