Banca de DEFESA: ALANDERSON FIRMINO DE LUCAS

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : ALANDERSON FIRMINO DE LUCAS
DATE: 31/01/2022
TIME: 09:00
LOCAL: Vídeo conferência
TITLE:

THE IMPACT OF DESERTIFICATION ON HYDROLOGY: A MODELING STUDY FOR THE SERIDO RIVER BASIN

KEY WORDS:

desertification, semiarid, hydrological modeling, SWAT.

PAGES: 124
BIG AREA: Ciências Exatas e da Terra
AREA: Geociências
SUBÁREA: Meteorologia
SPECIALTY: Meteorologia Aplicada
SUMMARY:

Land use in the Seridó river basin is the main factor in the intensification of desertification in this region, whose phenomenon interferes with the hydrology of the basin. Among its effects on the soil are the low quality and the change in the availability of water resources. The objective of this study was to evaluate the impacts of desertification on the hydrological response and on the water balance of the Seridó river basin, using hydrological modeling. The hydrological model used was SWAT, which proved to be an effective tool, as it satisfactorily simulated the seasonality of the monthly flow (Q) in four tributary sub-basins of the Seridó River, simulating the observed flow variance by more than 60%. In the evaluation of the dexterity of the model, it was observed that the simulation of the Q with greater dexterity were those equal to or less than Q5% (maximum flows) and the PBIAS (RMSE) of the simulated flow was ~ 30% (8.3 m³.s-1 ) and 50% (11.8 m³.s-1) for the calibration and model validation periods, respectively. To assess desertification, two land use and land cover scenarios (LULC, Land Use and Land Cover) were developed for the hydrographic basin: the control scenario, where the vegetation cover of the basin was that observed in 1985; and the desertification scenario, where desert areas were included from 1985 to 2019. The historical and gradual advance of the desert (15.39% of the basin area) altered the annual water balance, increasing the total runoff (Qtot ) by 6.95%, due to the significant increase in surface runoff (Qsurf), which increased by 12.08%. This change altered the maximum flow regime associated with floods, which were considerably increased in the desertification scenario. In annual mean absolute terms, the changes were 14 mm.month-1 and +11 mm.month-1 in the wet season, respectively. On the other hand, subsurface runoff (Qlat) decreased by 15.34% in relation to the annual balance, although it increased by 1.5 mm.month-1 in the rainy season. The annual evapotranspiration (ET) () reduced by 4.18%, which corresponded to -5 (-2) mm.month-1 in the rainy (dry) season. The same impact occurred with soil water content (SW) and percolation (Wperc). In these components, the average annual reductions were 3.79% and 1.96%, -45 mm.month-1 and -4 mm.month-1 in the rainy season, respectively. In spatial terms, with desertification ET, SW, Wperc (Qtot, Qsurf and Qlat), were significantly reduced (increased) in the central-west region of the basin. Studies using remote surface sensing confirm that desertification in the semi-arid region of northeastern Brazil has been installed and has progressed annually, at least since the 1980s. Studies evaluating the hydrological effects caused by this process in the theoretical sphere are rare, or inexistent, that is, hydrological modeling. This study contributes in this direction, and in general, we observed that desertification increased the extremes of maximum flow, while it deteriorated the hydrological conditions, locally and in the areas adjacent to the desert regions, with the reduction of the water content in the soil and the percolation. As a result, the maintenance of natural and agricultural ecosystems will be harmed, as they will have a lower supply of water for the ET, and reduced percolation, unbalance the groundwater system.

BANKING MEMBERS:
Presidente - 2411669 - JONATHAN MOTA DA SILVA
Interno - 842.400.082-04 - GABRIEL BRITO COSTA - UFOPA
Externo ao Programa - 350698 - VENERANDO EUSTAQUIO AMARO
Externo à Instituição - LEONARDO MORENO DOMINGUES - INPA