Downstream fining in contrasting reaches of the sand‐bedded Yellow River

摘要: Compared to downstream fining of a gravel-bedded river, little field evidence exists support the process in large, fine sand-bedded rivers. In fact, typically unimodal bed sediments these rivers are thought produce equal mobility coarse and grains that may discourage fining. To investigate this topic, we drilled 200 sediment cores channel beds two fine-grained reaches Yellow River (a desert reach lower reach) identified surface layer (FSL) developed over subsurface (CSL) 3-m-thick deposits. both downstream, thickness FSL increased, while CSL decreased. Comparison depth-averaged median grain sizes separately shows distinct dependence size, which indicates at large scale 600-800 km, significant fining, but no trends variations size. This result supply ( 0·08 mm size) from wind-borne cross-desert tributaries can interrupt coarsen locally. Copyright © 2011 John Wiley & Sons, Ltd.