programme tuesday, july, 31 - Université de Caen Basse Normandie

Tidalites 2012, 8th International Conference on tidal environments, Caen, France – Abstract book
FACTORS INFLUENCING SEDIMENT MOBILITY ON THE INTER-TIDAL FLATS OF
THE UPPER GULF OF CALIFORNIA
Luis G. ALVAREZ, Rafael RAMIREZ
CICESE, Carretera Ensenada-Tijuana no. 3918, Zona Playitas, 22860, Ensenada, Mexico,
lalvarez@cicese.mx
The northwest end of the Gulf of California, north of 31º N, is known as the Upper Gulf of
California (UGC). It is a semi-enclosed shallow basin, surrounded by arid alluvial plains and
piedmont deposits. This high-energy macro-tidal sea has semi-diurnal tides with range 7-8 m
during springs, and currents 1-3 m/s. Damming and diversion of the Colorado River have
reduced freshwater and sediment supply to the UGC by more than 95% for over a century. On
the west coast, an extensive coastal plain of tidal flats extends from high tide to about 12 below
mean sea level. The intertidal flats are drained by numerous dendritic, linear, and even
meandering channels. Sediments are mainly reddish-brown mud. Sand is restricted to intertidal
sand flats, tidal channels and a narrow belt of steep beaches ((Thompson, 1969; Schreiber, 1969;
Meckel, 1975; Baba, et al., 1991).
Currents, tides, sediment properties and suspended sediment were measured on the
intertidal flats during five short-term (1-3 days) time series in 2001 and 2008-2011. The aim was
to identify for the first time the processes that dominate sediment transport.
During spring tides, exposed intertidal flats are more that 5 km wide at the northwestern
end of the UGC, decreasing to widths of ~1 km at the southern part, where the observations
were made. The main morphological elements at the observation site are low-relief (