Sediment input from fluvial sources and cliff erosion to the

ISLA, F; CORTIZO L C

Journal of Integrated Coastal zone Management

Portuguese association of water resources

Lugar: Lisboa; Año: 2014 vol. 14 p. 541 - 552

1646-8872

The  coasts  of  southern  Buenos  Aires,  Patagonia  and Tierra  del  Fuego  are  dominated  by  clif f erosion . Mea n rate s o f cli ff retre at are estimated  to  be  about  0.5-0.6  m/year  by  comparing  old  photographs  with  modern  satellite  images.  Considering  the  height  of  the Patagonian  and  Fueguian  cliffs  (70  to  120  m),  the  volume  of  sediment  eroded  from  these  cliff s exceede d th e volume s provide d by the erosion of the cliffs of Buenos Aires (10 to 20 m height). These erosion rates support an estimated delivery of 217 million tons of sediment per year to the continental shelf, exceeding significantly the 22 millions of tons/year transported by the larger Patagonian rivers Negro and Colorado. However, the contribution of these rivers has decreased since the Late Pleistocene changes in the direction of transport of some watersheds. The Chubut and Chico de Santa Cruz rivers suffered reductions of 21-24% in their watershed areas, resulting in reductions of about 33-34% in the volume of water transported to the Atlantic Ocean per year. As the amount of sediment delivered to the Argentine continental shelf by cliff erosion is higher than the fluvial transport, it should be also considered in the balance of beaches fed by longshore transport.