Réseau de drainage (géomorphologie)

Résumé

vignette|Drainage dendritique: Brahmapoutre, au Tibet, vu de l'espace: la couverture de neige a fondu dans le système de la vallée. En géomorphologie, les réseaux de drainage, appelés aussi réseaux hydrographiques (en anglais drainage systems, aussi connu sous le nom river systems), sont les réseaux formés par l'ensemble des cours d’eau (ruisseaux, rivières, éventuellement fleuve), des lacs et de leurs connexions d'un bassin hydrographique (bassin versant) donné. Ils sont régis par la topographie du sol, qu’une région donnée soit dominée par des roches dures ou tendres, et l’inclinaison du terrain. Les géomorphologues et les hydrologues considèrent souvent les cours d’eau comme faisant partie des bassins versants. Un bassin versant est la région topographique à partir de laquelle un cours d'eau reçoit les eaux de ruissellement, les affluents, les écoulements traversants (throughflow) et les écoulements souterrains. Le nombre, la taille et la forme des bassins versants trouvés dans une

Source officielle

https://fr.wikipedia.org/wiki/R%C3%A9seau_de_drainage_(g%C3%A9omorphologie)

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Multiple Inflow Branches at Supercritical-Type Vortex Drop Shaft

Gaetano Crispino, Thierry Fuchsmann, Corrado Gisonni, Michael Pfister, Jean-Marc Ribi

Vortex drop shafts serve to overcome important elevation differences in drainage systems. If well designed, they are performant in terms of energy dissipation and safety. However, the standard design requires well-defined approach flow conditions to ensure the reliability of the structure. In practice, these conditions are frequently ignored due to space restrictions and the fact that several inflow branches may arrive at various elevations with supercritical and/or subcritical flows. The literature provides preliminary concepts for such situations that were not adaptable to the case discussed herein. Nevertheless, in order to apply a standard vortex drop shaft, a novel concept was developed that comprises a junction chamber to merge the inflow branches followed by a very short and steep inlet channel. Extended physical model tests have proven its feasibility. The hydraulic aspects discussed herein allow, at least partially, the adoption of the presented concept in similar situations.

ASCE-AMER SOC CIVIL ENGINEERS2018

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This study describes transient hydrogeological and geomechanical models realized jointly in 2006 by the Geolep office (Géologie de l’Ecole Polytechnique) of the Polytechnical School of Lausanne (EPFL) and GeoMod SA within the framework of the stabilization work of the La Frasse landslide (Vaud, Switzerland). These models evaluate the impact of a deep drainage gallery with subvertical drainage boreholes towards the surface in terms of reduction of the deformation velocities and increase of the landslide’s factor of safety. The paper presents the effect of different pipe spacing of the drainage system. Considering the local heterogeneities, the results show that a mean spacing between the drainage boreholes of the order of 10 m is sufficient to control the temporal head fluctuations between the wells within a range of a few metres. Moreover, this solution induces a strong diminution of the predicted displacements during a specific crisis, from 101 cm for the model without drainage to around 14 cm for the drained model, and a significant gain of stability (from a factor of safety (FoS) of 1.05 to 1.30).

National Research Council Canada2012

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The geomorphometry of endorheic drainage basins: implications for interpreting and modelling their evolution

Jean-Marc Dorsaz, Andrea Rinaldo

Endorheic basins are catchments with no hydrological connection with marine environments. They cover 20% of the Earth's surface, and are mostly located in arid regions. Their drainage networks converge to lakes, salt flats or alluvial plains, whose dynamics are strongly driven by precipitation, evapotranspiration and groundwater discharge, among other factors. Integrated surface drainage and the creation of whole drainage systems typical of open basins are commonly restricted in these regions. Interestingly, the fluvial basin morphology of endorheic basins has not been extensively studied, and a variety of quantitative morphological descriptors used in open basins have not been utilized in the geomorphic analysis of endorheic basins. The objective of this study is to better understand the basin morphology of endorheic river basins by using well-known geomorphological properties and their variations across scales. For three basins in northern Chile we computed the following descriptors and the corresponding relevant scales: the cumulative distribution of contributing area, the horizontal shape of the basins (i.e. Hack's law, normalized Euclidean length, and sinuosity of the streams), slope-area relationship, Horton's ratios and drainage density. We detected several properties typically found in open basins, but certain features which seem to be unique to closed basins were also identified. In particular, we found that horizontal and vertical geomorphic features seem to be linked, which suggests that an independent treatment of these features may not be appropriate for closed basins. Similar results were found regardless of the basin area, which illustrates the relevant effects of features that are specific to these particular regions. It is expected that our findings will improve both the geomorphic assessment of these basins and hydrological modelling of surface water and groundwater. Copyright (c) 2013 John Wiley & Sons, Ltd.

Wiley-Blackwell2013

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The geomorphometry of endorheic drainage basins: implications for interpreting and modelling their evolution

Jean-Marc Dorsaz, Andrea Rinaldo

Wiley-Blackwell2013