التفاصيل البيبلوغرافية
| العنوان: |
Sediment gauging during flood events in the Middle Loire Rationale and results |
| المؤلفون: |
Gautier, Jean-No?l, Rodrigues, St?phane, Peters, Jean, Peeters, Pierre, Jug?, Philippe |
| المصدر: |
La Houille Blanche; October 2008, Vol. 2008 Issue: 5 p71-78, 8p |
| مستخلص: |
A hydraulic and sediment transport survey campaign was organised in March 2007 on the Loire River, at the Br?h?mont site. The aim was to collect data useful for the understanding of fluviomorphological mechanisms. A survey procedure, established at the end of the 1960's and relying on a follow-up bathymetric surveys and ancient sediments samplers was combined with modern technologies such as DGPS satellite positioning and ADCP flow gauging. The survey campaign allowed quantifying the sediment transport rates of the size fractions larger than 50 microns. The results confirm the earlier made hypothesis concerning the existence of a sediment load moving close to the bottom and distinct from the suspended load as described in the theories. This load was called " morphological " and is composed of solids having sizes between those of the river bed and those moving in suspension at higher elevations. This statement, made on the basis of surveys on other large streams in Africa, Asia and the America's questions the concepts on which have been based the majority of the sediment transport theories. The present surveys show that campaigns as these are necessary in order to comprehend the processes, a condition prior to investigating solutions.Une campagne de mesures hydrauliques et de transport solide a ?t? effectu?e en mars 2007 sur la Loire moyenne sur le site de Br?h?mont. Elle avait pour but de recueillir des donn?es utiles ? la comprehension des m?canismes fluviomorphologiques. Un protocole de mesures mis au point ? la fin des ann?es 1960 croisant un suivi bathym?trique et le d?ploiement d'?chantillonneurs iso-cin?tiques a ?t? mis en ?uvre parall?lement ? des techniques plus modernes, telles que positionnement par satellite et jaugeages liquids avec ADCP. La campagne de mesures a permis de chiffrer le transport solide des fractions granulom?triques sup?rieures ? 50 microns. Les r?sultats obtenus confirment les hypoth?ses ?mises pr?c?demment concernant l'existence d'une charge solide transport?e pr?s du fond et qui se distingue de la charge de suspension telle que d?crite dans les th?ories. Cette charge a ?t? baptis?e " morphologique " et est compos?e de sediments dont les diam?tres se situent entre ceux du lit fluvial et ceux de la suspension ? des niveaux plus ?lev?s. Cette constatation, faite ? partir de mesures sur d'autres grands fleuves en Afrique, Asie et Am?riques met en question les concepts sur lesquels sont bas?es la plupart des th?ories de transport solide. Ces mesures montrent que des campagnes de ce genre sont n?cessaires pour comprendre les processus, condition pr?alable ? la recherche de solutions. |
| قاعدة البيانات: |
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