Simulação do fenômeno de infiltração em modelos chuva-vazão

Abstract

This work concerns infiltration hydrological process simulation in rainfall-runoff models, emphasizing its influence on runoff generation. Based on physical principles of water flow through porous media, an extension of Green & Ampt's equation (Morel-Seytoux e Khanji,1974; Morel-Seytoux, 1978) was been used to estimate infiltrated water and excess rainfall volumes. Simulated values showed good agreement when compared with Richards' equation numerical solution. Green & Ampt's infiltration parameters - wetting-front pressure head Ψf’ and hydraulic conductivity at natural saturation K sat - were estimated from soil characteristic curves (matric potential x moisture retention). These curves can be obtained through Rawls, Brakensiek and Saxton's (1982) regression models, using particle size distribution, bulk density, organic matter percentage, and moisture retention under -1500 kPa and -33 kPa, available data on SISSOLOS - Soil Information System from EMBRAPA (Agricultural and Animal Husbandry Brazilian Research Agency). Soil characteristic curves for 16 brazilian soils (41 horizons) were generated from these models, and compared with observed values. Good results came from application of Model number 3. Finally, viscosity and soil properties spatial variability effects on infiltration and excess rainfall modeling were briefly analyzed. Similar media and scaling factor concepts were introduced in order to simulate soil spatial variability.