Four-decades of bed elevation changes in the heavily regulated upper Atchafalaya River, Louisiana, USA
نویسندگان
چکیده
Previous studies have established that under natural conditions, alluvial river confluence zones experience channel scour followed by mid-channel bar development. Less attention is given to bed evolution downstream of large confluences engineered such as discharge regulation and levee confinement. Here we present four decades morphologic changes along the 69-km uppermost Atchafalaya River, a distributary Mississippi River Outflow Red River. We aim find answer one critical question: how does an engineering-controlled respond regulated flow? utilize single-beam bathymetry data collected in 1967, 1977, 1989, 1998, 2006 quantify riverbed deformation reach after flow began 1963. Suspended sediment load stream power during decadal periods are calculated. Results show between 1967 2006, extensive degradation occurred average elevation reduced 3.8 m. A total volume 105 ± 26 × 106 m3 was scoured from over this 40-year period, implying erosion has contributed coarse delivery associated deltaic growth Bay. Bed aggradation only 1989–1998 response excess input likely attributable 1993 long-lasting flood. But same amount deposit eroded following eight years, demonstrating quickly can diminish perturbation owing input. These findings not reveal complexity adjustments intensive engineering disturbances but also provide useful information for future modeling management plans other large, confluences.
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ژورنال
عنوان ژورنال: Geomorphology
سال: 2021
ISSN: ['0169-555X', '1872-695X']
DOI: https://doi.org/10.1016/j.geomorph.2021.107748