Sources and sinks of sediments to
the Amapá Coast.
Odete Fátima Machado da Silveira
Valdenira Ferreira dos Santos
FORCING MECHANISMS
• Large M2 tidal
amplitude at the south,
near ressonance that
results from a concave
shoreline trend and
shore-perpendicular
Cabo Norte shoal;
• Semi diurnal tidal
range producing
shorenormal tidal
currents changes from
erosion (Southern
Amapá) to shoreline
accretion – mudflats
north of Cabo
Cassiporé;
• Fluid muds diminushes the bottom drag
coefficient retarding the tidal waves
progression;
• Advection of the low salinity plume of
Amazon river along the Amazon Shelf
(northwest) due the interaction of:
seasonal trade winds (easterly); surface
gravity waves and NBC;
• High suspended sediments concentration
nearshore (varies temporaly and spatialy
with de factors above mentioned and with
the Amazon river discharge;
Two more mechanisms can be add:
•The pororoca phenomena;
• Antrophic components.
The Sources
• Erosional processes;
Rio Cassiporé
Rocinha-Araguari
Cunani
The sources
•Sediment supply
Aporema
Uaçá
The sinks of sediments
Changes over 26 years at Amazon River Mouth
1972
1997
2000
1992
Ig.Novo
Livramento do Bailique
Ig.Novo
Sucuriju-Cabo Norte
Anthropic components
Artificial tidal channel
Igarapé República- Estuarine Sector – Amapá coastal zone.
Acervo:GERCO
Depositing and reworking sediments
How to study environments highly energetic with shallow
waters, macrotides and high mud sedimentation/ressuspention?
750 mg/l