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Universidade Federal do Rio Grande do Norte (UFRN) 2020

Resposta hidrológica da bacia hidrográfica do rio piancó às mudanças climáticas

Meira, Yasmim Cristina Leiros

Titre : Resposta hidrológica da bacia hidrográfica do rio piancó às mudanças climáticas

Auteur : Meira, Yasmim Cristina Leiros

Université de soutenance : Universidade Federal do Rio Grande do Norte (UFRN)

Grade : Mestrado Em Ciências Climáticas 2020

Résumé
Climate change is an increasing issue with interference in various sectors of society, especially the water sector. As water resources gain more emphasis due to the increasing demand, it is crucial to understand the effect of climate change on hydrological cycle components on a watershed scale for the management of water resources. Thus, the aim of this study was to analyzethe impacts of climate change on the hydrological response of the Piancó River basin,located in the Brazilian semiarid region. The assessment of these impacts was based on simulations with the distributed hydrological model Soil Water Assessment Tool (SWAT) for the currentclimate and for two different greenhouse gas (GHG) emission scenarios, RCP 4.5 and RCP 8.5, in the near future (2022-2043). For the hydrological simulation of the currentclimate, a set of daily meteorological data from surface stations, regularly arranged in space with a resolution of 25 km, was used. For the near future climate, the meteorological data from the MCG projections of the Coupled Model Intercomparison Project Phase 5 (CMIP5) were used, specifically, the projections of the MIROC5 model, with regionalized precipitation and temperature for a horizontal spacing of 25 km. The average hydroclimatic projections ofthe basin in the near future resultedin a slight increase in precipitation (3%) and water yield(1.4%) for the scenario RCP 4.5, for RCP 8.5 considerable reductions in precipitation (6.5%) and water yield(14%). The contribution of runoff to the water yieldincreased in both scenarios, reaching 78% (RCP 4.5) and 80% (RCP 8.5), while the subsurface and base runoff predictions for the contribution of the water yieldwere down up to 14% (RCP 4.5) and 13% (RCP 8.5), and 13% (RCP 4.5) and 7% (RCP 8.5), respectively. Part of these effects is associated with the forecast of change in the annual precipitation cycle of the river basin (RCP 4.5 and RCP 8.5), which will change the beginning, the end, and the seasonal magnitude of the hydrological flows. The effects on hydrological flows during the wet season (Jan-May) for both scenarios, showed the same reduction disposition, being more intense in RCP 8.5.During the dry season (Jun-Dec), in general, the tendency of the scenarios RCP 4.5 and RCP 8.5 was to increase and decrease, respectively. In the evaluation of the projection of seasonal water availability, in the wet season, the average flow should reduce by 15% (RCP 4.5) and 31% (RCP 8.5), and in the dry season it should reduce, advancing the intermittency of the Piancó river for both scenarios. For extreme flows, the forecasts showeda reduction in the wet season, 4% (RCP 4.5) and 2.5% (RCP 8.5), and an intense increase in dry season with changes of 243% (RCP 4.5) and 143% (RCP 8.5).The decrease in water availability and the increase in extreme flows are alarming results

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