Endoréisme

Résumé

vignette|upright=1.5|Le delta de l'Okavango, au Botswana, partie la plus basse d'un bassin endoréique d'Afrique australe (image satellite). En hydrologie, l’endoréisme (du grec ancien : [« couler »] avec le préfixe endo- [« dedans »] et le suffixe -isme) d'un cours d'eau ou d'un bassin versant est le fait qu'il ne se déverse pas dans une mer, mais est au contraire clos, retenant ses eaux (superficielles ou non) dans une cuvette fermée. Les pluies ou autres formes de précipitations qui l'alimentent le quittent uniquement par évaporation . Caractéristiques vignette|Le lac Hart dans le bassin du lac Eyre en Australie. L'endoréisme . L'endoréisme a plusieurs causes, souvent cumulées :

l’endoréisme structural est la conséquence du relief, dans le cas de cuvettes fermées de toutes tailles ;
l’endoréisme fonctionnel est la conséquence de facteurs et au climat (forte évaporation le long des cours d'eau ou dans les lagunes).

Quoique les bassins endoréiques puissent se trouve

Source officielle

https://fr.wikipedia.org/wiki/Endor%C3%A9isme

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2011

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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 Qiangtang Basin is a large endorheic basin in the inner part of the Tibetan Plateau and has been thought to be a dry region in contrast with its wet surrounding outer region that feeds all the major Asian rivers. Combining surface hydrological data with modelling and satellite data between 2002 and 2016, our study reveals that an enormous amount of water, approximately 54 ± 4 cubic kilometers, is unaccounted for annually in the Qiangtang Basin. The amount of missing water is comparable to the total annual discharge of the Yellow River. Data from the Gravity Recovery and Climate Experiment (GRACE) show little increase of local terrestrial water storage. Thus, the missing water must have flowed out of the basin through underground passages. Interpreting this result in the context of recent seismic and geological studies of Tibet, we suggest that a significant amount of meteoric water in the Qiangtang Basin leaks out by way of groundwater flow through deep normal faults and tensional fractures along the nearly N-S rift valleys that are oriented sub-normal to and cross the surficial hydrological divide on the southern margin of the basin. Cross-basin groundwater outflow of such a magnitude defies the traditional view of basin-scale water cycle and leads to a very different picture from the previous hydrological view of the Qiangtang Basin. The finding calls for major rethinking of the regional water balance.

2021

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