Ajustements géomorphologiques du chenal de la moyenne Garonne en aval de Toulouse au cours des 200 dernières années (sud-ouest, France)

Abstract

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Species composition and plant traits: Characterization of the biogeomorphological succession within contrasting river corridors

“…The hydrological regime of the Allier is pluvial (Onde, ), whereas the regime of the Garonne river is pluvio‐nival (Pardé, ). In contrast to the laterally unconstrained, unchannelized lower Allier River (Garófano‐Gómez et al, ), the middle Garonne River was heavily impacted by river bank protections (riprap), sediment mining, and upstream dam construction during the second half of the 20th century, leading to channelization and vertical incision of the river channel (Jantzi, Carozza, Probst, & Valette, ; Steiger, James, & Gazelle, ).…”

Les formes d’érosion en lit mineur rocheux : typologie, distribution spatiale et implications sur la dynamique du lit. Exemple à partir des seuils rocheux molassiques de la moyenne Garonne toulousaine (Sud-Ouest, France)

“…), ainsi que les extractions de granulats, ont contribué au tarissement des apports solides et à un déficit sédimentaire en moyenne Garonne. Cela s'est traduit par un enfoncement moyen du lit de 1 m avec des valeurs pouvant atteindre localement 2,7 m (Jantzi et al, 2017a ;Jantzi, 2018). Parmi ces activités, les extractions qui ont eu lieu sur chacun des sites, représentent le principal facteur d'apparition des seuils rocheux.…”

“…As with many European rivers, the River Garonne (SW France) has significantly changed its morphology and hydro-sedimentary dynamics during the 20 th century as a result of the narrowing and incision of its riverbed, especially from the 1950s onwards (Jantzi et al, 2017a). In fact, this period corresponds to a big increase of human interference in the channel, with an intensification of in-stream mining in almost the entire channel (Beaudelin, 1989;Jantzi et al, 2017b).…”

“…If the channel incision has been reported since the early 1980s (Lambert, 1989;Beaudelin, 1989;Steiger et al, 1998Steiger et al, , 2000, knickpoints and sculpted forms have been very poorly studied (Jantzi et al, 2017a;Jantzi, 2018). Until today, few studies have been carried out on stratified sedimentary rocks such as molasses.…”