@article{fdi:010066261,
  title = {{R}ole of flocculation and settling processes in development of the mangrove-colonized, {A}mazon-influenced mud-bank coast of {S}outh {A}merica},
  author = {{G}ratiot, {N}icolas and {A}nthony, {E}. {J}.},
  editor = {},
  language = {{ENG}},
  abstract = {{T}he {G}uianas coast downdrift (northwestward) of the {A}mazon {R}iver mouth is characterized by the periodic migration of mud banks that originate from the {A}mazon. {T}he characteristic sizes of these banks as well as their rates of alongshore migration have been estimated from remote sensing. {H}owever, the physical mechanisms leading to their displacement are not yet fully understood. {T}he present work is aimed at investigating a number of micro-scale processes involved in the coastal and estuarine dynamics of fine sediments, and expected to occur during the migration of mud banks. {T}he relative magnitudes of flocculation, hindered settling and consolidation have been determined. {S}ampling of coastal mud was carried out during a field survey in 2001 that focussed on the fluid mud layer in the leading edge of a mud bank in {F}rench {G}uiana. {S}ettling column experiments were conducted under quiescent conditions for various mean sediment concentrations in the range of 2.5-110 g.l(-1), which is typical of mud bank concentrations. {T}he time dependent vertical profiles of suspended sediment concentration were monitored using an optical settling tank equipped with 32 pre-calibrated optical sensors. {T}he corresponding settling velocities were deduced from the equation of the conservation of mass. {T}he results show that the timescales of hindered settling and consolidation processes are much larger than the timescales of mixing mechanisms such as tides or propagating waves. {T}he individual floc settling velocities are too small to counterbalance the turbulent mixing induced by breaking waves. {H}indered settling, favoured by wave action and by the high background suspended sediment concentrations, is thus an overarching process in wave-driven mud bank migration. {T}his pervasive hindered settling regime is characteristic of the wave-exposed outer and leading edges of mud banks where active mobilization of mud assures mud bank migration. {A}s a result, consolidation is theoretically precluded. {T}he experiments pointed out, however, that additional flocculation and differential settling should enhance sedimentation during slack water and under low wave conditions. {W}e deduce from this that enhanced settling in the inner,subtidal-intertidal, parts of leading edges of banks during such conditions is important in the temporary sedimentation that generates gel-like fluid mud patches and mud bars. {T}hese low-energy inner, leading parts of banks form an accreted substrate colonized by mangroves, which further contribute to enhanced settling and rapid sedimentation.},
  keywords = {{F}locculation ; {H}indered settling ; {S}ettling by mass ; {M}ud bank ; {M}uddy coast ; {M}angroves ; {A}mazon-{O}rinoco coast ; {GUYANE} {FRANCAISE} ; {AMAZONE} {COURS} {D}'{EAU} ; {ORENOQUE} {COURS} {D}'{EAU} ; {KAW} {ESTUAIRE}},
  booktitle = {},
  journal = {{M}arine {G}eology},
  volume = {373},
  numero = {},
  pages = {1--10},
  ISSN = {0025-3227},
  year = {2016},
  DOI = {10.1016/j.margeo.2015.12.013},
  URL = {https://www.documentation.ird.fr/hor/fdi:010066261},
}