inscription
Portail d'information géographique

Résultats de la recherche (31 résultats)

Affinez votre recherche

Par Collection Par Auteur Par Date Par Sujet Par Titre
  • Knickpoint evolution in rillwash
  • This paper describes laboratory experiments carried out with improved methodology to extend Bryan and Poesen's (1989) results. The object was to obtain detailed information on development of knickpoints, as a first stage in testing possible linkages
  • A demonstration of the importance of bedload transport for fluvial bedrock erosion and knickpoint propagation
  • Carrying capacity ; Fluvial erosion ; Geological structure ; Knickpoint ; Lithology ; Longitudinal section ; Sediment load ; Stream ; Taiwan
  • the 1999 Chi-Chi earthquake. For 5 years following the earthquake, bedload was prevented from entering the uplift zone, the knickpoint was static and little incision took place. Bedload transport across the uplift zone resumed in 2004, initiating extremely
  • rapid incision, with 620 m of knickpoint propagation and up to 20 m of downcutting by 2008. This change highlights the relative inefficiency of suspended sediment and the dominant role of bedload as a tool for fluvial erosion and knickpoint propagation
  • . Knickpoint propagation was influenced by geological structure, lithology, and drainage organization. In particular, a change in dip of the sandstone beds at the site caused a decrease of knickpoint propagation velocity.
  • Hillslope response to knickpoint migration in the Southern Appalachians: implications for the evolution of post-orogenic landscapes
  • Appalachian Mountains ; Conceptual model ; Erosion ; Knickpoint ; Longitudinal section ; Mass movement ; Model ; North Carolina ; Post-orogenic evolution ; River bed ; Slope gradient ; Spatial distribution ; United States of America ; Watershed
  • Values of normalized hypsometry, hypsometric integral, and mean slope vs elevation are used in south-western North Carolina for 14 tributary basins and the Cullasaja basin as a whole to characterize landscape evolution following upstream knickpoint
  • migration. Results highlight the existence of a transient spatial relationship between knickpoints present along the fluvial network of the Cullasaja basin and adjacent hillslopes. This transient effect of knickpoint-driven channel incision on basin
  • hillslopes is captured by measuring the relief, mean slope steepness, and mass movement frequency of tributary basins and comparing these results with the distance from major knickpoints along the Cullasaja River. A conceptual model of area–elevation
  • The purpose of this paper is to analyse the controls on knickpoint location and migration along the canyon of Nahal Paran in southern Israel. Nahal Paran contains several active and buried knickpoints, as well as an inner channel hypothesized
  • to have been created through headward knickpoint migration. The location of these features depends in part on lithologic variability and tectonic uplift as they influence channel morphology and gradient, which in turn influence hydraulics and sediment
  • Knickpoint recession rate and catchment area : the case of uplifted rivers in Eastern Scotland
  • Knickpoint (KP) recession in streams draining to glacio-isostatically uplifted shorelines in eastern Scotland is used to assess wether KP recession is a function of discharge ( here represented by its surrogate, catchment area). Knickpoints
  • 'n Ondersoek van die puinafsettings in die noordelike knakpunt van die Daspoortrand naby Pretoria. (Investigation of deposits in the northern knickpoint of the Daspoort ridge near Pretoria)
  • laboratory analysis were made of the exposed gravel deposits at the Daspoort ridge tunnel. From this investigation the tentative conclusion was made that there appeared to be two main periods of debris and one of sand deposition in the knickpoint
  • Sediment movement and knickpoint behavior in a small piedmont drainage basin
  • Evidence of transient topographic disequilibrium in a landward passive margin river system : knickpoints and paleo-landscapes of the New River basin, southern Appalachians
  • Appalachian Mountains ; Cenozoic ; Drainage network ; Glacial features ; Inheritated geomorphological features ; Knickpoint ; Topography ; United States of America
  • decoupled hillslopes from the drainage network, generating knickpoints which represent the boundary between remnants of the paleo-landscape and actively adjusting topography downstream. In the absence of tectonic forcing, the AA. favor a climatically-forced
  • Channel geometry ; Downcutting ; Fluvial dynamics ; Knickpoint ; Longitudinal section ; Model ; Stochastic model ; Stream
  • to predict patterns of deformation from channel long profile inversion or to model knickpoint migration and landscape evolution. Numerous studies have attempted to test its applicability with mixed results prompting the question of its validity. This paper
  • Danube ; Floodplain ; Fluvial deposit ; Holocene ; Hungary ; Hydrology ; Knickpoint ; Slope ; Spatial distribution ; Tectonics
  • major knickpoints formed on the margin of subsiding basins, in the zone of deep structure cutting across the country in NE to SW direction as well as on the E and SE margin of the uplifting Hungarian Mountains. The less remarkable knickpoints
  • to effectively replicate the different mechanisms. These experiment roughly emulate natural fluvial processes including aggradation, lateral erosion, degradation, knickpoint retreat, ponding, and overflow. The experiments address landscape morphology
  • Prefecture, Japan), and Kegon Falls (Tochigi Prefecture, Japan). The results are summarized in a table. It is suggested that recession of waterfalls (or knickpoints) is a significant factor in the development of fluvial landforms.
  • Amazon Basin ; Base level ; Brazil ; Drainage network ; Fault scarp ; Fluvial capture ; Knickpoint ; Numerical model ; Pleistocene ; Response time ; Tectonics ; Watershed
  • knickpoints was generated by base-level fall following drainage capture; through numerical modeling of their initiation and propagation, the capture event is inferred to have occurred between the middle and late Pleistocene, consistent with other studies
  • Carrying capacity ; Channel geometry ; Fluvial geomorphology ; Knickpoint ; Mountain ; South Carolina ; Step-pool channel ; Stream ; United States of America
  • morphology (bedforms) were sampled and analyzed. Structurally controlled bedrock knickpoints are associated with anomalous spatial patterns of bedforms and can be distinguished through relationships between dimensionless sediment transport capacity
  • features with higher frequency of caves, collapsed dolines, sinkholes and resurgences in pure quartzite (Q) and in areas with high relief, but there is no lithological control on solution dolines. Gullies, knickpoints and captured valleys are also
  • not controlled by lithology or relief. The results suggest a fluvial control of gullies and depositional features in valley bottoms caused by headward erosion, after underground captures or knickpoint disruption.
  • . The results suggest three general mechanisms by which bedrock channels erode: 1) vertical wearing of the channel bed due to stream flow; 2) scour by periodic debris flows; and 3) knickpoint propagation. Consequently, application of a single erosion law
  • a revision of Holocene (ground)water gradient lines. A knickpoint in these gradient lines can be related to the effect of faulting.
  • points along the length of the Atenguillo River: Volcan La Laja, Volcan La Cienega, Volcan El Vigia. The high incision rates, as well as 2 distinct knickpoints along the profile of this river are related to a base level change at the northern end
  • size, new field observations suggest that the channel was actually eroded by local runoff. Water from several tributaries collects into a single channel at this point, and the resulting discharge is apparently sufficient to cause retreat of a knickpoint
  • . Channel enlargement and knickpoint retreat, initiated by these changes, is ongoing, and the implications of this for land and heritage management in the region are discussed. A conceptual model is presented.