Supply and Removal of Sediment in a Landslide‐Dominated Mountain Belt: Central Range, Taiwan

A strong coupling between hillslope and valley systems is often inferred for mountain landscapes dominated by bedrock landsliding. We reveal the nature of this link using data sets on landsliding and sediment transport from two montane catchments draining the eastern Central Range of Taiwan. Here, t...

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Bibliographic Details
Published in:The Journal of geology 2000-01, Vol.108 (1), p.73-89
Main Authors: Hovius, Niels, Stark, Colin P., Hao‐Tsu, Chu, Jiun‐Chuan, Lin
Format: Article
Language:English
Subjects:
Fluvial transport
Landslides
Landslides & mudslides
Mass wasting
Mountains
Sediment transport
Sediment yield
Sediments
Streams
Suspended solids
Valleys
Watersheds
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Summary:A strong coupling between hillslope and valley systems is often inferred for mountain landscapes dominated by bedrock landsliding. We reveal the nature of this link using data sets on landsliding and sediment transport from two montane catchments draining the eastern Central Range of Taiwan. Here, the magnitude‐frequency distribution of landslides can be modeled by a robust power law, but this scale invariance is not mirrored in the sediment discharge at the mountain front. Instead, downstream sediment loads reflect a complex response to both sediment supply and ambient hydraulic conditions. The rivers do not transport significant amounts of sediment unless it is provided by hillslope mass wasting in the catchment. Removal of landslide debris is a function of the transport capacity of the stream at the site of entry; thus, there is a dual supply and transport control on sediment loads in bedrock‐floored streams. Over a monitoring period of >25 yr, the bulk of the sediment leaving the mountain belt was supplied by climate‐triggered mass wasting. Peaks in water discharge were always closely followed by sediment load maxima, and the rapid decay of the latter indicates an effective removal of most supply. Where an important part of a catchment's sediment yield is derived from interfluves, sediment transport cannot simply be estimated from known water discharge time series, using a sediment rating curve, but requires instead a detailed knowledge of the spatial and temporal patterns of hillslope mass wasting and sediment transfer into the fluvial system.
ISSN:0022-1376
1537-5269
DOI:10.1086/314387