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Cross‐channel mixing and its effect on sedimentation in the Orinoco River
Author(s) -
Stallard R. F.
Publication year - 1987
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/wr023i010p01977
Subject(s) - tributary , floodplain , sedimentation , foreland basin , hydrology (agriculture) , geology , sediment , structural basin , channel (broadcasting) , deposition (geology) , drainage basin , geomorphology , geography , geotechnical engineering , engineering , cartography , electrical engineering
At high discharge, cross‐channel mixing of water in the Orinoco River main stem requires several days and up to 500 km of downriver transit for completion. During mixing, substantial amounts of < 0.063 mm sediment are lost from suspension. The water closest to the left bank appears to lose the most, probably by deposition onto the floodplain. This occurs in two ways. First, sediment‐laden left‐bank tributaries draining the Andes, such as the Apure, deposit sediment in distributary systems following impoundment by the Orinoco backwater. Second, when sediment‐laden waters from the Andes actually join the Orinoco, the slow nature of cross‐channel mixing causes the water and sediment to be confined more to the left side of the channel. Significant sediment loss or storage probably occurs only near flood stage. Since sedimentation occurs preferentially on the left (Andean foreland basin) bank, the Orinoco remains stably situated on the border of the foreland basin with the Guayana shield.