| Popis: |
L’hydrogeomorphologie fluviale est peu reconnue dans les politiques de gestion et d’amenagement du territoire quebecois. Une meilleure reconnaissance permettrait pourtant une gestion plus eclairee des cours d’eau par une integration de leur dimension dynamique. Cette etude teste l’applicabilite d’une methode de sectorisation de cours d’eau en unites morphodynamiques homogenes. Cette compartimentation resulte d’une division longitudinale sur la base des changements des valeurs de puissance specifique, de composition sedimentaire des berges, du confinement dans la vallee et de geometrie planimetrique. La caracterisation est appliquee a un corridor de la riviere Neigette comportant une diversite de formes et de processus frequemment retrouves dans les rivieres du Quebec. Les resultats suggerent la presence de trois unites morphodynamiques: divagant a chenaux multiples, meandres dynamiques et meandres stables. La methode presente une forte capacitea discriminer ces environnements morphodynamiques ainsi que leurs limites respectives. La puissance specifique presente a elle seule une forte capacite de discrimination. L’efficacite de la demarche, l’aisance de son application et sa flexibilite font de cette approche un solide outil a integrer dans le processus de gestion des environnements fluviaux. An illustrated methodology for the morphodynamic sectoring of the Neigette River (Quebec) Fluvial hydrogeomorphology is little recognized in policy management and planning in Quebec. A better understanding would result in more enlightened planning for waterways. The deficiency could result from the fact that too few methodologies have been developed that take account of the particular nature of Quebec rivers. This study tests the applicability of a methodology of dividing rivers into homogeneous morphodynamic units. This compartmentalization results from the analysis of longitudinal changes in stream power, sedimentary composition of the banks, channel entrenchment, and planform geometry. The method is tested on a section of the Neigette River, which encompasses a wide variety of forms and processes frequently found in Quebec rivers. Results suggest the presence of three morphodynamic sections: wandering with multiple channels, dynamic meandering and stable meandering. The method provides an effective basis for discriminating between these morphodynamic environments and their respective limits. Stream power is the variable with the greatest discriminating capacity. The efficacy of the approach, the ease of its application, and its flexibility make this a valuable tool for the management of fluvial environments. |
