Cenários de disponibilidade hídrica para concessão de outorga: estudo de caso da Bacia Vertentes do Rio Grande

Abstract

The State Water Resources Policy aims to ensure the control, for current and future users, of water use and its use in quantity, quality and satisfactory regime. The current legislation provides, as one of the instruments for water resources management, the granting of water use rights. The granting guarantees to the holder, for a pre-established period and in a personal and non-transferable manner, the right to use a certain amount of water, subject to its availability, assuring the managing institution the quantitative and qualitative control of that use. As only part of the minimum reference flows are granted, there is a limitation of water use, especially in periods of greater water availability, affecting different users and their economic activities. Thus, it is necessary to analyze the influence of the seasonality of the flows in the criteria of granting water use. Therefore, searching for alternatives for the management of water resources, adapting the criteria to the local conditions of water availability, without exceeding the capacity of the water bodies and maintaining minimum residual flows in the watercourses. Nowadays, the uses of water resources in the Rio Grande Water Resources Planning and Management Unit (UPGRH-GD2) are mostly to meet the needs of activities such as livestock, agriculture, industry and for public supply. In light of the relevant economic activities mentioned, it is necessary to adopt criteria that portray the water seasonality in the river basin, to analyze the applications for granting in the UPGRH-GD2. In this context, the present study was carried out with the objective of evaluating the regionalization of seasonal flow, in the most diverse reference flows, verifying the possibility of the increase in water availability for the different UPGRH-GD2 users. In order to carry out this study, the software SisCah 1.0 and SisCorv 1.0 were used, selecting the fluviometric stations of the region that presented data related to the period from 1967 to 2002, as well as the analysis of the granting database of the Minas Gerais Institute of Management Waters - IGAM. The results obtained allowed to conclude that the use of the criteria based on the seasonal water behavior facilitates flexibility in the flow rates in the rainy season of the year, for the reference flows Q7,10, Q90% and Q95% and restriction on the use, during the dry season, for the reference flows Q90% and Q95%.