Modelagem numérica de infiltração de água: dois sistemas de cobertura final de aterro sanitário no Vale do Rio dos Sinos

Abstract

Numerical calculation methods have become much more efficient, making their application in problem-solving increasingly widespread. User-friendly interfaces make model configuration much easier and more intuitive, while the increase in computer speed can solve difficult problems in a matter of minutes. A series of computational models for estimating rainfall processes and their impact on the performance of landfill cover systems have become valuable tools in contemporary times, especially for evaluating the final cover layer of compacted soil. Among them, one of the most notable is HYDRUS-1D, a software based on the Finite Element Method that simulates the one-dimensional movement of water, heat and solute in variably saturated porous media for various limit conditions, including precipitation and evaporation. HYDRUS 1D was used to model the water balance in final cover layers of sanitary landfills in the Vale do Rio dos Sinos, using laboratory data on granulometry, Atterberg limits, compaction, permeability and suction of soils collected in São Leopoldo and Esteio (RS), and adjusting meteorological series (1991–2020) of precipitation, temperatures, relative humidity, evapotranspiration, insolation and wind by multiple linear regression (adjusted R² ≈0.895) for the months of highest and lowest rainfall; the performance of conventional and evapotranspiratory cover systems was compared in a one-dimensional regime, finding that the evapotranspiratory cover significantly reduces water percolation by keeping the soil in an unsaturated condition for longer; It is concluded that the integration of characterization tests, statistical analysis and numerical simulation provides precise subsidies for the dimensioning and selection of materials, contributing to the minimization of environmental impacts associated with water inlet the landfill.