Avaliação da remoção de material particulado em canal raso gramado
Shinzato, Alexandre Hideki
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The study conducted examined the sediment removal behavior for a lawn channel built full-scale, 100 m in length, slope of 2% and wide base of 0.7 m in the Federal University of São Car them, San Carlos - SP. For this analysis, we simulated runoff for three volumes of downloads 5; 7; 10 m³, represented each with their respective hydrograph and blade height by passing the flood wave. These flows were mixed with the particulate material produced from the local ground of the campus area, sieved to smaller than 75 micron, which is used for varying the initial concentration for tests. The experimental data were fit to a model first order decay, Meira optimum slug flow in through non-linear regression using decay kinetic parameters (k d) and equilibrium concentration (C *). Fractions removed and the mathematical adjustment were evaluated and executed for each single event along the length of the lawn channel monitored in 26 positions. The peak of the hydrograph was investigated in the range of 11 ± 2 L / s and time base (tb) determined at the unloading point on the channel varied from 15, 25 and 35 minutes. The transit time in the channel (tT) was approximately 10.5 ± 2.5 m, corresponding to 0.14 ± speed 0,02 m / s. The maximum efficiency of particulate matter removing over the lawn channel length ranged from 47 to 81% in 20-90 m positions. Whereas all concentrations of investigates, it was found that for 15 minutes tB, the average maximum efficiencies were on the order of 64 ± 3% to ± 26 position of 31 m. TB to 25 minutes the average maximum were of the order of 73 ± 3% to 59 ± 24 m positions. Finally, for 35 minutes tB the average maximum efficiencies were obtained in the range of 65 ± 3% in the 73 ± 15 m positions. The ratio tb / tT correlated 0.98 with the position of maximum efficiency. The maximum removal positions are related to the decay constant (Kd). It was found that 70% of the values of the decay constant (Kd) is between 0.005 and 0.015 s-1, and to disregard the hydrograph represented by tB 15 minutes, 90% of the data is contained in it Halftone 0.005 Kd ≤ ≤ 0.015 s-1 and 85% in the range 0.007 ≤ 0.012 ≤ Kd s-1. It was identified direct and proportional relation of the equilibrium concentration (C *) and initial concentration (Co).