scholarly journals Mississippi River and Tributaries flowline assessment : Atchafalaya River sedimentation model report

2019 ◽  
Author(s):  
James Lewis ◽  
Ronald Copeland
Keyword(s):  
Mississippi River ◽  
Atchafalaya River ◽  
Sedimentation Model

scholarly journals Floodplain biogeochemical processing of floodwaters in the Atchafalaya River Basin during the Mississippi River flood of 2011

2014 ◽  
Vol 119 (4) ◽  
pp. 537-546 ◽  
Author(s):  
Durelle T. Scott ◽  
Richard F. Keim ◽  
Brandon L. Edwards ◽  
C. Nathan Jones ◽  
Daniel E. Kroes
Keyword(s):  
River Basin ◽  
Mississippi River ◽  
Atchafalaya River ◽  
River Flood ◽  
Atchafalaya River Basin

scholarly journals Estimation of sedimentation rates in the distributary basin of the Mississippi River, the Atchafalaya River Basin, USA

2013 ◽  
Vol 46 (2) ◽  
pp. 244-257 ◽  
Author(s):  
Timothy Rosen ◽  
Y. Jun Xu
Keyword(s):  
River Basin ◽  
Mississippi River ◽  
Landsat Imagery ◽  
Open Water ◽  
Water Area ◽  
Sedimentation Rates ◽  
Sediment Retention ◽  
Annual Average ◽  
Atchafalaya River ◽  
Atchafalaya River Basin

The Atchafalaya River Basin (ARB) is the largest distributary basin of the Mississippi River composing anastomosing channels, backwater swamps, freshwater marshes, and wetland forests. Sedimentation in the ARB has presented management issues concerning habitat changes from open water areas to bottomland hardwood forests. A thorough understanding of sediment transport and deposition in the basin is not only required for proper management of the ARB, but is crucial for regional sediment budgets that affect the Mississippi River Delta Plain. In this study, we calculated 31 years (1980–2010) of total suspended sediment (TSS) inflow and outflow of the Atchafalaya River to quantify the long-term sediment retention in the basin. We then estimated sedimentation rates in the basin by spatially relating the retention with changes of turbid water area derived from Landsat imagery. The study found an annual average TSS inflow of 54.0 megatonnes (MT) and an annual average TSS outflow of 48.7 MT, resulting in an average annual retention of 5.3 MT. Spatially derived mean sedimentation rates were estimated between 0.06 and 0.153 mm d−1. The spatial estimates for sedimentation proved promising and with more sediment data available could become an invaluable tool for managing the ARB in the future.

scholarly journals Riverbed Changes of the Uppermost Atchafalaya River, USA—A Case Study of Channel Dynamics in Large Man-Controlled Alluvial River Confluences

Water ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 2139
Author(s):  
Bo Wang ◽  
Y. Jun Xu ◽  
Wei Xu ◽  
Heqin Cheng ◽  
Zhongyuan Chen ◽  
...  
Keyword(s):  
Mississippi River ◽  
River Flow ◽  
River Mouth ◽  
Red River ◽  
Atchafalaya River ◽  
Alluvial River ◽  
Drag Forces ◽  
Confluence Zone ◽  
River Confluences

River confluences are important nodes for downstream sediment transport and geomorphological development. Previous studies have established the knowledge that under natural conditions, river confluence zones experience channel scour followed with middle channel bar development. Less care is however given to the intensity of a confluence scour zone under man-controlled conditions, such as discharge regulation and levee confinement. In general, our knowledge about long-term bed evolution downstream of large alluvial river confluences is limited. Here we conducted a study focused on the 69-km uppermost channel of the Atchafalaya River, the largest distributary of the Mississippi River, to test the hypothesis that the channel downstream of two large tributaries sustains longer-term, extensive bed scouring owing to increased discharge in the main channel and, therefore, mid-channel bars in such a confluence zone cannot be built under confined channel conditions. The Atchafalaya River carries the total flow from the Red River and approximately 25% of the Mississippi River flow, traveling southwards 230 km before emptying into the Gulf of Mexico. We utilized long-term records on water surface elevation and discharge during 1935–2016, as well as channel bathymetry survey data during 1998–2006 to determine changes in hydraulic head and morphologic deformation in the confluence zone. The results from this study show that the combined flow from the Red River and Mississippi River into the Atchafalaya River steadily increased to approximately 5848 cubic meters per second (m3 s−1) in the recent decades, and the channel bed of the uppermost Atchafalaya River experienced considerable erosion since the 1930s. At a specific discharge of 8000 ± 100 m3 s−1, the river stage decreased by 5.8, 5.6, and 4.9 m from 1935 to 2016 at (from upstream to downstream) Simmesport, Melville, and Krotz Springs gauging stations, respectively. The average bed elevation reduced by 1.9 m from 1998 to 2006, although its thalweg increased by 0.3 m. Based on the channel bed assessment, a total volume of 6.6 × 107 m3 sediment was eroded from the uppermost 69 km of the Atchafalaya over the 8 years. The findings suggest that confluence zones of large alluvial rivers under controlled flow and confined levee conditions can experience extensive, long-lasting channel erosion. This can be especially progressive if the channel below a confluence is confined by levees, which can increase drag forces and prevent middle channel deposition. Further studies are needed to determine if the eroded sediment from the uppermost Atchafalaya is carried out to the river mouth or is deposited in the lower Atchafalaya. Such knowledge will have both scientific and practical relevance in river engineering and management.

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