Diagnóstico da disponibilidade hídrica superficial da bacia hidrográfica do rio Suaçuí-MG e os impactos dos usos insignificantes de água

Abstract

Water availability is the primary information that supports the analysis and decision on the granting of the right to use water resources for a given claim, and thus ensures the quantitative and qualitative control of water uses and the effective exercise of water access rights, as provided for in article 11 of Federal Law No. 9,433, which institutes the National Water Resources Policy. It also defines that the derivations, funding and entries considered insignificant are independent of granting. Establishing limits for these uses has always been a difficult task, each local water resources management sphere assigns these limits according to specific characteristics and needs, whether they are defined by type of use, by volume of water, or the lack of “free uses”. In Minas Gerais, to obtain the registration of insignificant use, the user must fill out a specific form, informing the flow, purpose and mode of use of the water resource, among other general information, and the registration is then issued instantly. The hypothesis of this work is that records of insignificant uses for the capture of surface water emitted in series along small stretches of a watercourse may have the capacity to substantially alter its water availability, and consequently, cause environmental impacts, as well as providing conflicts over the use of water and not guaranteeing the supply between multiple uses. The general objective of the research is to analyze the State Water Resources Policy of Minas Gerais, with regard to insignificant uses, contributing to the knowledge of the interference of these uses in the water availability of the hydrographic basin, based on quantitative aspects, taking as an area of study the hydrographic basin of the Suaçuí River.To achieve the proposed objective, the list of users of surface water collection at the study site was obtained from the Minas Gerais Water Management Institute - IGAM. The water availability calculations for the basin were made, as well as for stretches of water courses, analyzing the interferences of insignificant uses. The results showed that water abstraction does not impact the water availability of the basin, considering the total availability, except for the sub-basin of the Corrente Grande river, where it was found to be compromised. Insignificant uses do not significantly interfere with the water availability of those stretches that have licensed users. In the analysis of all stretches in which insignificant uses are present, it was found that 555 are in a situation of unavailability, with most of these stretches of small extension, located in headwater regions, and also stretches where there are two or more captures considered insignificant, or in consecutive stretches. This result suggests that the way in which registries of insignificant uses are granted should be revised, based on the water availability of the stretch to be demanded, and not just limited by a maximum flow.