L'action de la neige est aussi importante dans l'espace et dans le temps que celle de la glace. L'A. définit un certain nombre de seuils géomorphiques liés à la nature et à l'état de la neige, à la présence ou à l'absence ainsi qu'à la durée et à
Geomorphic threshold conditions for ephemeral gully incision
Belgique ; Drainage ; Erosion des sols ; Pente de versant ; Propriétés du sol ; Précipitation ; Ravinement ; Ruissellement ; Seuil ; Utilisation du sol ; Versant
Geomorphic thresholds were defined initially as the condition at which there is a significant landform change without a change of external controls such as base level, climate and land use. Landforms evolve to a condition of incipient instability
and extrinsic geomorphic thresholds. The threshold concept has practical significance. If the threshold conditions can be recognized, not only will different explanations for some landforms emerge but also the ability to identify incipiently unstable landforms
related to dynamical (in)stability. Unstable interactions among geomorphic system components tend to dominate in earlier stages of development, while stable limits often become dominant in later stages. This results in mode switching, from unstable
Downstream geomorphic variation and local bedrock influence of a steep transitional river : Blue Ridge to Piedmont, South Carolina
Blue Ridge ; Capacité de charge ; Chenal seuil-fosse ; Cours d'eau ; Etats-Unis ; Géomorphologie fluviale ; Géométrie hydraulique ; Montagne ; Rupture de pente ; South Carolina
Spatial patterns in geomorphic variations are examined in a river transition from the Southern Blue Ridge to the Piedmont physiographic regions. Downstream hydraulic geometry (DHG), fining of bed material, and changes in reach-scale channel-bed
Ajustement ; Barrage ; Catastrophe ; Concept ; Cours d'eau ; Etats-Unis ; Géométrie hydraulique ; Illinois ; Mouvement de masse ; Profil longitudinal ; Seuil
damming and avulsion of Little Cassy Creek. Slope and river disruptions were linked because the effect of one event (slope failure) was the cause of the second event (fluvial avulsion). Criteria needed to employ thresholds to explain geomorphic events
are not linear but rather approximate a power relation. Different relations were found for lahar initiation in different years, from 1991 to 1997, as a result of the dynamic changes in hydrologic and geomorphic conditions of the affected catchments. Data from
Piping susceptibility and the role of hydro-geomorphic controls in pipe development in alluvial sediments, Central Spain
Définition de valeurs-seuils des propriété des sols pour rendre compte du phénomène de piping dans les sédiments alluviaux des ranas du centre de l'Espagne. La macroporosité et le développement des fentes dans les sols sont des facteurs favorables
Lacustrine record of high energy geomorphic events in the Sawtooth Range, Ellesmere Island, Canadian High Arctic
processus de versants à l'échelle locale, et les épisodes d'accroissement de l'activité des mouvements de masse à des endroits spécifiques sont contrôlés par des seuils géomorphologiques intrinsèques.
Sensitivity of landscape evolution and geomorphic processes to direct and indirect human influence
in several study areas are analysed. Data obtained indicate that people are nowadays the main geomorphic agent. It is proposed that growing population, wealth and technology is the driving force behind a widespread global geomorphic change that affects
landscape sensitivity. The effect of geomorphic change is added to that of climate change and implies an acceletation of landscape evolution rates as well as an intensification of geomorphic hazards. It is suggested that measures to mitigate geomorphic
change should be taken in order to curb the observed trend towards increasing geomorphic disaster occurrence. - (NF)
are considered and tested against the data set available. A few equations relating the main geomorphic parameters are obtained. They can be used for river restoration and paleohydrological inference. The jamming factor (ratio between the size of the coarser
Années 2004-2011 ; Capacité de charge ; Chenal seuil-fosse ; Cours d'eau ; Crue ; Dynamique fluviale ; Erlenbach ; Erosion fluviatile ; Géométrie hydraulique ; Préalpes ; Suisse ; Transport sédimentaire ; Vitesse d'érosion
flows. Flood-depositing streams deposit during high flows and erode during small and medium flows. Using published descriptions of the geomorphic effects of large floods, rivers with a wide range of drainage areas are classified as either flood-cleaning