Os cenários de mudanças climáticas se mostram cada vez mais severos, e se apresentam ainda mais intensos para regiões como o semiárido nordestino. O presente estudo buscou analisar os cenários de mudanças climáticas e seus impactos em uma pequena bacia hidrográfica no semiárido pernambucano. Os cenários de alterações na precipitação e temperatura foram simulados utilizando Sistema de Unidades de Respostas Hidrológicas para Pernambuco (SUPer) que conta com um gerador climático que permite simular mudanças climáticas dentro de uma série histórica, os dados dentro do sistema SUPer foram gerados através do modelo SWAT-Soil Water Assessement Tools. Os dados obtidos para os cenários apontam para uma redução significativa na disponibilidade hídrica na bacia, com redução do fluxo de base e aumento da perda por evapotranspiração em todos os nove cenários analisados, o que é um grande impacto, pois trata-se de uma região onde já há um déficit hídrico.Palavras-chave: Balanço hídrico, Mudanças climáticas, Semiárido.                                                                                                                                 Water Balance and Climate Change in the Semiarid region of Pernambuco: applicability of the System of Hydrological Response Units for Pernambuco (SUPer)  A B S T R A C TClimate change scenarios are increasingly severe, and are even more intense for regions such as the semi-arid northeast. This study aimed to analyze the scenarios of climate change and its impacts in a small watershed in the semi-arid region of Pernambuco. The scenarios of changes in precipitation and temperature were simulated using Hydrological Response Units System for Pernambuco (super) which has a climate generator that allows to simulate climate change within a historical series, data within the super system was generated through the SWAT--Soil Water Assessement Tools. The data obtained for the scenarios point to a significant reduction in water availability in the basin, with reduction of the base flow and increase of the loss by evapotranspiration in all nine scenarios analyzed, which is a great impact, region where there is already a water deficit.Keywords: Water balance, Climate change, Semi-arid.

The Brazilian northeast has a characteristic relationship with water resources because, in this region, water scarcity is associated with natural factors and accentuated by anthropic actions that interfere with water quality. The present work aimed to perform a temporal analysis of the water quality of the Nilo Coelho reservoir, municipality of Terra Nova, a semi-arid region of Pernambuco. Initially, the parameters of dissolved oxygen, nitrate, and phosphorus, available in the system of hydrological response units for Pernambuco (SUPer), following the resolution of the National Environment Council (CONAMA), for the years 1963–2021, were analyzed. Subsequently, land use and occupation mapping were carried out to identify the activities that developed in the region. The result of the analysis of water quality for the Nilo Coelho reservoir classifies it as little compromised, since the parameters are within acceptable limits, with greater variations for phosphorus. Regarding the use and occupation of the soil, there was an increase in water availability and agricultural areas, with a reduction in the caatinga. Continuous monitoring of water quality in the reservoir is recommended, in addition to the application of SUPer and land use and occupation maps as tools for the management of water resources.

Monitoring water quality is essential to understand the situation of water resources, especially in regions suffering from water scarcity, such as the Brazilian Northeast. The present study aimed to analyze the water quality of the Nilo Coelho reservoir, Terra Nova, using the Water Quality Index proposed by CETESB. Data provided by the HidroWeb portal of the National Water and Basic Sanitation Agency were used. The reservoir has monitoring data for the years 2016 to 2022, still in the present study, the collections from 2019 to 2022 were used because they had the necessary parameters for calculating the index. The parameters used were thermotolerant coliforms, biochemical oxygen demand, total phosphorus, pH, total dissolved solids, temperature, turbidity, dissolved oxygen and nitrate. The results were compared with the limits established by CONAMA No. 357/2005. Among the parameters analyzed, only thermotolerant coliforms, total phosphorus and BOD were outside the limits set by the legislation, which may indicate outbreaks of pollution in the reservoir. The application of the IQA indicates that the water in the reservoir can be classified as good, showing that the water is suitable for human supply. However, continuous monitoring of the region's water is of paramount importance, in addition to the adoption of public policies that encourage the proper management of the areas surrounding the reservoir, since it is receiving water from the São Francisco River transposition project.