GEOMETRY MEASUREMENT VERSUS ROUGHNESS CALIBRATION: APPLICATION TO AMAZON RIVER

摘要

On large rivers, Manning coefficient generally varies between low flow and high flows. Actually, an insufficient description of the channel geometry can account for a significant part of this variation. This is shown on Amazon River where the roughness calibration is conducted at high and low flow, using two different geometry data sets. In order to determine appropriate cross section spacing, a more accurate geometry is build. Observing from measurements that bed width and flow depth are highly correlated, which can be explained by sediment transport considerations, a procedure to generate profiles with a low spacing is developed. For that, bed widths are assessed from radar remote sensing images. The analysis confirms the role of the geometry description on Manning coefficient variations.