A curva de permanência e a disponibilidade hídrica para outorga no estado do Paraná

Abstract

One of the main means from the National Water Resources Policy is the granting of rights to use water resources, which ensures the quantitative control of water and the right of accessing water by different users. The granting criteria are based on water availability indicators or reference flows, whose Q90 and Q95 duration flows are the most used ones by the Brazilian states. Thus, in order to draw flow duration curves, different time units can be adopted, such as the long period curves, which use the whole historical series; the annual flow duration curves created for each year of the recording period; the monthly flow duration curves, drawn for each month of the historical series; or the seasonal flow duration curves, based on the seasons. The unit of time, selected to draw the flow duration curves, will influence on details of flow variation. Therefore, this study aimed at comparing different ways of elaborating flow duration curve and observing its effects on water availability for granting in Parana state. Fluviometric stations were distributed throughout Parana state and, in order to observe the variations in reference flows, some were prepared: a) duration curves of long period; B) annual flow duration curves, obtained by a non-parametric quantile estimator, and confidence intervals were drawn to quantify the uncertainty associated with each estimated quantile; c) monthly flow duration curves, prepared by the equivalent months of the whole historical series. The influence of the selected period got clear to draw the duration curves as this trial was carried out in water availability for granting. And, granting criterion values are more flexible when the interannual and seasonal flows variations are considered