GOMEZ Eduardo Alberto
congresos y reuniones científicas
Evaluation of sand transport models by in situ observations under unidirectional flow.
GÓMEZ, E. A.; AMOS, C. L.; LI, M. Z.
Itajai;, Santa Catarina, Brasil
Simposio; International Coastal Symposium 2004; 2004
Sand transport rates measured from nine deployments of an annular benthic flume off the western Newfoundland coast and Sable Island Bank (Canada), are compared with predictions using: (1) Engelund and Hansen?s total load equation; (2) Einstein-Brown?s bedload equation; (3) Bagnold?s total load equation, modified by Gadd et al.; and (4) Yalin?s bedload equation. The D50 grain diameters examined were: 0.19 mm (15 trials); 0.33 mm (37 trials); and 0.50 mm (7 trials). Results showed that equation (1) under-predicted in about a 40% for all the grain sizes. Equations (2) and (4) showed almost the same range of under-prediction: approximately 30% for D50 = 0.19 mm, 40% for D50 = 0.33 mm and 50% for D50 = 0.5 mm. The maximum variations on the observed-predicted ratios were obtained by equation (3), over-predicting by a factor of 2.45 and 1.9 for D50 = 0.19 mm and D50 = 0.33 mm, respectively, and under-predicting by a factor of 0.42 for D50 = 0.5 mm, but showing the highest correlations among all the tested models (R2= 0.96 and 0.8 for D50 = 0.19 mm and 0.33 mm, respectively). These variations are related to the inclusion of outliers in the original computation of the grain size dependent â-parameter employed by equation (3). Based on the obtained results and through the analysis of published data, a significant improvement on the formulation (3) is suggested.