Modelagem matemática do escoamento superficial na escala de encosta sob plantio direto

Abstract

The runoff generation over fields with no-tillage agriculture management remains being a problem with environment, social and economic impacts. The purpose of this research was evaluate the capacity of a physic based and distributed model (LISEM) to simulate the generation and propagation of the runoff over hillslopes cultivated with no tillage system during monitored rainfall events. The field experiment is located in Júlio de Castilhos, central region of Rio Grande do Sul state, on Fepagro - State Foundation for Agricultural Research. Was investigated the Lisem model capacity to simulate the generation and propagation of the runoff over different areas, four of them with approximately 0.5 ha with different soil and cover management systems, and one with approximately 2.5 ha with presence of ephemeral channels. From most of the rainfall events monitored during 2015 and 2016 years, five was chosen that generated runoff over all fields to calibrate the model parameters, two of them considered of low magnitude, two of high magnitude and one of extreme high magnitude. The calibration of the model was designed by changing the saturate soil hydraulic conductivity, initial soil water content, surface Manning’s coefficient and aleatory roughness of the soil, to fit the peak of flow discharge, total volume discharge and hydrograph shape. In general, the model performed well on simulate the runoff dynamics, especially the extreme high magnitude rainfall event, responsible for the most of environment impacts, water and soil losses. LISEM model can be an option in studies to better understanding the hydrological process behavior of the runoff generation, and as a decision tool in recommendations of more efficient practices to excess runoff control, contributing to decrease the water erosion, soil losses and improving the soil and water quality.