In this paper were study five components of the flow regimen with ecological importance on fluvial ecosystems were studied. The magnitude, duration, timing, frequency and rates change of flow. Thirty-two parameters were used as the Indicators of Hydrological Alteration (IHA). From diary hydrologic data of Porto São José gauge station in the high Paraná River, were calculate the mean values of the indicators, coupled with the standard deviation and minimum and maximum absolute values for the pre and post-dams periods was calculated, with the aim of comparing and evaluating the magnitude of the observed alterations of the flow regimen. For it's, was applied the method the "Range of Variability Approach" (RVA). The most significant results suggest changes in low-flows related indicators and are largely a reflection of the control of debts by upstream reservoirs. Such indicators presented increase in magnitude, accompanied by declining in frequency. Other changes in the magnitude of the stream flow are related to the use and occupation processes of the basin. Hydrologic changes have changed the behavior erosive-deposicional, sediment transport and primary production in the River and adjacent fluvial plain.
Hydrologic Regimen; Dams; Land Use; Parana River
