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Causes and consequences of seasonal changes in the water flow of the São Francisco river in the semiarid of Brazil

2020; Elsevier BV; Volume: 8; Linguagem: Inglês

10.1016/j.indic.2020.100084

2665-9727

Anderson dos Santos, Pabrício Marcos Oliveira Lopes, Marcos Vinícius da Silva, Alexandre Maniçoba da Rosa Ferraz Jardim, Geber Barbosa de Albuquerque Moura, Gabriel Siqueira Tavares Fernandes, Douglas Alberto de Oliveira Silva, Jhon Lennon Bezerra da Silva, Joez André de Moraes Rodrigues, Emanuel Araújo Silva, José Francisco de Oliveira‐Júnior,

Hydrology and Watershed Management Studies

The objective of this study was to evaluate the causes and consequences of changes in the water flow of the São Francisco River, on the border between the states of Sergipe and Alagoas, a Brazilian semiarid region. For this, we used images from the Landsat-8 satellite, OLI sensor, with a spatial resolution of 30 ​m. The results found in this study reveal two distinct behaviors in the study region of the Low São Francisco watershed, the first encompassing more homogeneous areas and with greater environmental preservation located in the West and the second encompassing heterogeneous areas with severe environmental degradation in the east of the study region. In general, due to the occurrence of exposed soil, thin vegetation, and regions of the high declivity, the basin has a high and very high degree of vulnerability in 73.8% of its land, with serious risks of desertification. According to the results of the Normalized Difference Water Index (NDWI), there was a drastic reduction in the surface area of water bodies along the São Francisco River channel, evidenced in the period from 2013 to 2018, with the expansion of sandbank areas in 17.7 ​km2. Agricultural and livestock activity was configured as an important factor in increasing land vulnerability. The evidence in this study suggests that changes in land use and coverage induce increases in the sandbank areas within the river channel, even in periods of greater water volume, which causes the silting up of the São Francisco river bed in its low course.