Análise do comportamento hidrológico da bacia do rio Ipanema a partir da projeção de cenários modelados utilizando SWAT

• Autor(a) principal: Farias, Ramiro Ferreira dos Santos
• Data de Publicação: 2020
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da UFS
• Texto Completo: https://ri.ufs.br/jspui/handle/riufs/14272
• topic: Recursos hídricos; Modelagem hidrológica; Ipanema, Rio (SE); São Francisco, Rio; SWAT; Soil and water assessment tool; Hydrological modeling; ENGENHARIAS::ENGENHARIA SANITARIA

Caatinga deforestation is one of the main aggressions to the environment in the Brazilian semiarid region. This deforestation harms all the environmental dynamics and directly interferes with the hydrological behavior of a basin. As a result, this study carried out the calibration of the Soil and Water Assessment Tool (SWAT) hydrological model. An attempt to simulate events and scenarios occurring in the Rio Ipanema River Basin (BHRI) sub-basin of the São Francisco River. The purpose was to evaluate trends in how changes in coverage and land use interfere with the flow regime of the Ipanema River, which has already been greatly impacted by man. Four scenarios of land use and land cover simulation were considered between 1980 and 2016, totaling 37 years of simulation. They were: real coverage conditions (current scenario), using a coverage raster and 2011 use of the MAPBIOMAS 4.0 series, and three extreme projected scenarios, considering total conversion to pasture, forest and agricultural areas. The settings were made using the QSWAT Land Use Update (.LUP) tool, after the calibration and model validation procedure. The calibration reached an NSE of 0.61, PBIAS of -8.5 and an R² of 0.62, being considered acceptable to proceed with the simulation, however the validation did not obtain a good result reaching an NSE of 0.45, PBIAS of -6, 27 and an R² of 0.50, these problems occurred due to the low availability of flow data and hydrological monitoring in addition to the poor quality of the available data. The modeling also made it possible to obtain other information related to the geographical space of BHRI, such as: predominance of soil types with emphasis on the eutrophic litholic neossol (24.84%), eutrophic regolitic neossol (25.21%), planossol eutrophic haploid (40.70%); main types of cover and use, the pasture being responsible for covering 63% of the basin's territory, forests 28% with the majority in permanent protection areas; and predominant slope in the range of 3% to 8% with 40% of the land, 0% to 3% with 30%, and 8% to 20% with 19% of the land. As for the simulated scenarios, the forest cover scenario was responsible for raising, in a more significant way, the evapotranspiration rates (Δ <35 mm Current, and Δ> 45 mm Forests), underground water flow (Δ <37 mm Current, and Δ> 40 mm Forests) and water production in the basin (Δ <45 mm Current, and Δ> 47 mm Forests), in contrast to the current scenario and total coverage by pasture with the lowest rates for these variables. When analyzing the sediment production in the basin, the influence of the scenarios changes, with agriculture with the highest sediment production predominating, and the forest with the lowest sediment production (Δ> 0.045 t / ha Agriculture, and Δ <0.01 t / ha Forests). It is worth considering that deforestation, mechanization, soil disaggregation and poorly planned planting and irrigation can cause soil loss, this means generation and transportation of sediments towards the water courses. This context reinforces the importance of maintaining and preserving native forests in strategic areas such as riparian forests and areas of buffering and permanent preservation around lakes, lagoons, reservoirs and springs. BHRI's current scenario is worrying, since, from the point of view of water resources, it evidences a situation of water scarcity that compromises the affluence in the main channel of the river and consequently the water availability for the population, for agriculture and for the animal watering. BHRI's SWAT model achieved favorable results and has the potential for further research related to soil management and cover versus water production. New studies on pedology and geology in the basin area are also needed to assess the influence of these geomorphological characters on water resources at BHRI.