Modelagem da disponibilidade hídrica na Bacia do Alto do Paraguaçu

Abstract

The upper Paraguaçu river basin, located in the Chapada Diamantina region, Bahia, has been undergoing an intense process of change in its landscape caused by the expansion of agricultural areas, making it necessary to adopt instruments for studies that evaluate environmental impacts, mainly on resources. surface water. Given this, the present work aimed to evaluate the hydrological behavior of the upper Paraguaçu basin using the SWAT model (Soil and Water Assessment Tool), in order to understand the dynamics of water and land use over time (1984 to 2021), with the aim of evaluating the evolution of land use and occupation and the impact on the hydrological response of the Paraguaçu basin. The methodology of this study consists of 02 stages: (I) Acquisition of the Database: 1) Physical variables: Digital Elevation Model, pedology and land use and occupation. 2) Daily data on precipitation, wind speed, relative humidity, minimum and maximum temperature, solar radiation from 1985 to 2021; and (II) Hydrological modeling with SWAT manually in 03 periods: warming (1984-1986), calibration (1987-2006), validation (2007-2021), respectively. The results of the comparison between flow observed and simulated by SWAT in the period from 1984 to 2021 showed results from the model efficiency analysis with an Efficiency Coefficient The NashSutcliffe Efficiency Coefficient of 0.68 and an Average Error = -0.16 m³ .s-1. The most sensitive parameters of the model were related to the physical properties of the soil and management, such as the curve number, available water capacity and hydraulic conductivity. In 2021, the maximum and average flow values fell by 45% and 26.79%, in that order, and the minimum reduced by approximately 12.75% compared to 1985. Indicating a reduction in the average minimum flows in this basin. There were inconsistencies in the flow data, which made it impossible to make future predictions, requiring further calibrations. The suggestion for future work is to carry out flow regionalization, a technique used to estimate fluviometric data in places without measurements, applying information from similar river basins.