Avaliação da disponibilidade hídrica superficial na bacia hidrográfica do Rio Uraricoera, Roraima

Abstract

The Uraricoera River Basin (BHU), located in the northwest of Roraima, Brazil, is a region of great hydric importance. However, it remains underexplored in detailed studies on the availability and management of its water resources. This study aimed to evaluate the surface water availability in the BHU. The research focused on specific aspects such as precipitation analysis, hydrological year definition, estimation of minimum reference flows (Q7,10, Q95 and Q90), and assessment of the balance between water demand and availability. The methodology included the collection and analysis of hydrometeorological data from rain gauge and flow gauge stations, the application of statistical methods and geoprocessing tools to fill data gaps, and the use of probability distribution models to estimate reference flows. The results showed that the highest precipitation levels in the BHU occur upstream, with significant seasonal variability in the rainfall regime, where the wet season is concentrated between April and August. The concentration of water withdrawals near the river's mouth revealed an imbalance in the allocation of water use permits, emphasizing the need for more balanced management strategies. Additionally, the analysis of minimum reference flows indicated that Q90 exhibited the highest water availability, with a Hydric Commitment Index (HCI) below 50%, suggesting favorable conditions. Conversely, the adoption of 50% of Q7,10 revealed a scenario of unavailability, with an HCI above 100%, highlighting management challenges during droughts or periods of high demand. As a final product, this study resulted in the elaboration of the technical note Hydrometeorological Situation and Water Availability of the Uraricoera River Basin/RR, a practical tool that consolidates these findings and provides support for the efficient and sustainable management of BHU's water resources.