Paléo-dynamique fluviale holocène dans le compartiment sud-occidental du Fossé rhénan (France)

Using transition matrices to assess the spatio‐temporal land cover and ecotone changes in fluvial landscapes from historical planimetric data

“…The study area is included in the historical Rhine braided‐anastomosing sector as defined by Carbiener and Dillmann (1992), which was extended and developed from Neuf‐Brisach to Strasbourg. This sector is unique along the Upper Rhine River in terms of fluvial dynamics and forms with a river bed aggradation since the post‐würmien period, due to a combination of several geomorphological Holocene drivers, even though all other reaches exhibit natural bed incision dynamics (Schmitt et al., 2016). The study reach was impacted by three engineering phases: (i) the Rhine correction from 1840 to 1880, which was designed to regulate the Rhine between dykes; (ii) the Rhine regularization from 1930 to 1960, which implemented fields of transverse groynes to improve navigation conditions; and (iii) by‐passing the corrected Rhine by the Grand Canal D'Alsace (GCA) following the construction of the Rhinau power plant and the construction of the Rhinau diversion dam from 1963 (Felkel, 1969).…”

Morpho-sedimentary characteristics of Holocene paleochannels in the Upper Rhine alluvial plain, France

“…In the French Rhine alluvial plain, the Pleistocene sediments, primarily gravel and sand deposited during glacial periods, intercalate with finegrain layers (sand, silt, and clay) attributed to warm periods. Hence, the superficial Holocene deposits generally have finer textures than the Pleistocene sediments (Simler et al, 1979), except on the historical Rhine braided belt (Schmitt, 2001;Schmitt et al, 2016).…”

“…Consequently, the longitudinal profile of the Rhine became more incised between the Basel-Neuf-Brisach and Strasbourg-Lauterbourg sections during the Holocene and remained unchanged or even rose slightly in the Neuf-Brisach-Strasbourg section (Carbiener, 1969(Carbiener, , 1983a. Thus, the Holocene Upper Rhine and its alluvial plain are classified into four major longitudinal sections based on geomorphological characteristics and dynamics (Carbiener, 1969(Carbiener, , 1983aSchmitt et al, 2016;Fig. 2).…”

“…The French Upper Rhine alluvial plain (eastern France) is characterized by a complex pattern of paleochannels inherited from the Late Glacial to Holocene fluvial dynamics of the Rhine and Ill rivers, as well as some other tributaries or sub-tributaries of the Rhine (Hirth, 1971;Carbiener, 1983a;Striedter, 1988). From Colmar to Sélestat, which is a part of the so-called "Ried central d'Alsace" (Carbiener, 1983a), the formation and evolution of the paleochannel network is attributed to significant landscape changes throughout the Holocene, as exemplified by the narrowing and eastward lateral migration of the Rhine fluvial hydrosystem and a westward displacement for its main tributary, the Ill River (Schmitt et al, 2016). Consequently, these paleochannels inherited from these lateral displacements preserve a comprehensive record of Holocene environmental changes, which is invaluable for understanding past landscape evolution and fluvial processes, as well as providing insights into the factors that controlled these changes (Bowler, 1978;Page et al, 1996;Dambeck and Thiemeyer, 2002;Sylvia and Galloway, 2006;Kemp and Spooner, 2007;Bisson et al, 2011;Nandini et al, 2013;Resmi et al, 2017).…”

“…Around the world, paleochannels have been extensively studied using a variety of methodological approaches in order to reconstruct the evolution of fluvial hydrosystems and associated landscapes in the geological and historical past (e.g., Page et al, 1996;Dambeck and Thiemeyer, 2002;Bos et al, 2008;Rossetti and Góes, 2008;Erkens et al, 2011;Plotzki et al, 2015;Jotheri et al, 2016;Resmi et al, 2017;Scorpio et al, 2018;Candel et al, 2020;Khosravichenar et al, 2020;von Suchodoletz et al, 2022). Likewise, in the Ried central d'Alsace, pioneering studies (e.g., Carbiener, 1969Carbiener, , 1983aHirth, 1971;Al Siddik, 1986;Boës et al, 2007;Schmitt et al, 2016) have investigated paleochannels and pa-leoenvironments with the aim to reconstruct the Holocene evolution of the landscape and/or study past human-river interactions. However, these research efforts lacked precision (e.g., no location of the sampling sites, no provenance study of fine sediments) or were, in many cases, concentrated around some archeological sites located close the village of Mussig (Boës et al, 2007) and focused on a rather limited number of paleochannels between the Rhine and Ill rivers.…”