HR: 0800h
AN: H11C-0669    [Abstracts]
TI: Flow resistance in step-pool channels
AU: * Canovaro, F
EM: francesco.canovaro@dicea.unifi.it
AF: CERAFRI-LAV (CEnter of Research and Advanced education For hydrogeological RIsk prevention), Via 11 Febbraio, 2, Retignano di Stazzem, LU 55040, Italy
AU: Bechi, G
EM: giulio.bechi@dicea.unifi.it
AF: Department of Civil and Environmental Engineering, University of Firenze, Via Santa Marta, 3, Firenze, FI 50139, Italy
AU: Solari, L
EM: luca.solari@dicea.unifi.it
AF: Department of Civil and Environmental Engineering, University of Firenze, Via Santa Marta, 3, Firenze, FI 50139, Italy
AB: Step-pools are characteristic bedforms that are common in steep mountain streams with gradients between 3% and 30%. The step-pool pattern plays a fundamental role in mountain stream hydraulics, developing the major portion of flow resistance. This flow resistance is essentially due to a loss of kinetic energy, dissipated by roller eddies that occur when water flows over a step rise and plunges into the pool below, creating a tumbling flow. An extensive laboratory experimental activity over a schematic arrangement of macro-roughness, represented by a regularly spaced stripe pattern, recently presented (Canovaro and Solari, 2007) has shown that when the macro-roughness is positioned according to an ‘optimal' spacing value flow resistance is maximum. A statistical analysis of a large amount of geometrical data about step-pool sequences observed in the field and reproduced in the laboratory suggests that this ‘optimal' spacing is close to what is frequently encountered in natural streams. Following such results both field measurements, concerning step-pool geometry and flow discharge, and numerical simulations have been started. The aim of this investigation is to validate the hypothesis that step-pool streams evolve towards a morphology that develops maximum flow resistance.
Canovaro, F. & Solari, L. (2007) "Dissipative analogies between a schematic macro-roughness arrangement and step-pool morphology". Earth Surface Processes and Landforms. (Accepted)
DE: 1800 HYDROLOGY
SC: Hydrology [H]
MN: 2007 Fall Meeting