Fluvial sediment transport and deposition following the 1991 eruption of Mount Pinatubo

TitleFluvial sediment transport and deposition following the 1991 eruption of Mount Pinatubo
Publication TypeJournal Article
Year of Publication2002
AuthorsHayes SK, Montgomery DR, Newhall CG
JournalGeomorphology
Volume45
Pagination211-224
Date PublishedJun
ISBN Number0169-555X
Accession NumberWOS:000176496600004
Abstract

The 1991 eruption of Mount Pinatubo generated extreme sediment yields from watersheds heavily impacted by pyroclastic flows. Bedload sampling in the Pasig-Potrero, River, one of the most heavily impacted rivers, revealed negligible critical shear stress and very high transport rates that reflected an essentially unlimited sediment supply and the enhanced mobility of particles moving over a smooth, fine-grained bed. Dimensionless bedload transport rates in the Pasig-Potrero River differed substantially from those previously reported for rivers in temperate regions for the same dimensionless shear stress, but were similar to rates identified in rivers on other volcanoes and ephemeral streams in and environments. The similarity between volcanically disturbed and and rivers appears to arise from the lack of an armored bed surface due to very high relative sediment supply; in and rivers, this is attributed to a flashy hydrograph, whereas volcanically disturbed rivers lack armoring due to sustained high rates of sediment delivery. This work suggests that the increases in sediment supply accompanying massive disturbance induce morphologic and hydrologic changes that temporarily enhance transport efficiency until the watershed recovers and sediment supply is reduced. (C) 2002 Elsevier Science B.V All rights reserved.