Hydrological modeling and scenarios of land use and climate changes in a representative basin, northeastern Brazil

Abstract

Water is a fundamental resource for life. The occurrence of extreme events has increased in recent decades. Understanding the effects of these events is extremely important for prevention and mitigation actions to be taken. This doctoral thesis addresses with issues related to water resources management and the impacts of land use and climate changes on the hydrological regime of the Mundaú River Basin (4,090.39 km²), northeastern Brazil. It aims to evaluate the uncertainties of the Soil and Water Assessment Tool (SWAT) calibration and validation processes and to simulate land use scenarios and future climate changes in the basin. Chapter 1 addresses the general introduction of the thesis, containing the hypothesis and general and specific objectives. Chapter 2 describes the hydro-environmental characteristics of the study area. Chapter 3 details the procedures adopted in the simulations with the SWAT model. Chapter 4 presents the evaluation of the uncertainties of the use of discharge and soil moisture data in the calibration and validation of the SWAT model in the Mundaú River Basin. Chapter 5 brings the evaluation of the effects of land use changes, based on the calibrated and validated SWAT model, on the evapotranspiration, surface runoff and sediment yield processes. Chapter 6 addresses the impacts of climate change on water resources in the basin, considering two scenarios of greenhouse gas emissions: Representative Concentration Pathways (RCPs) 4.5 and 8.5, and three time periods: short term, medium term and long term. Chapter 7 contains the general conclusions of the thesis. Finally, Chapter 8 presents a summary of the publications and other activities developed during the Doctoral research. We believe that the results found in this thesis are promising for the water management of the Mundaú River Basin, and will serve as a basis for the adoption of strategies to coexist with the scenarios of land use and climate predicted for the future. The SWAT model presented good performance and the calibration and simulation procedures adopted in this study can be replicated in other similar watersheds. The lessons learnt in this thesis may help researchers around the world to better understand the behavior of the hydrological processes of a northeastern Brazil basin under different land use and climate conditions.