The role of channel morphology on the mobility and dispersion of bed sediment in a small gravel‐bed stream          下载免费PDF全文

Elli Papangelakis  Marwan A. Hassan 《地球表面变化过程与地形》2016,41(15):2191-2206

This study uses a unique 10‐year tracer dataset from a small gravel‐bed stream to examine bed mobility and sediment dispersion over long timescales and at a range of spatial scales. Seasonal tracer data that captured multiple mobilizing events was examined, while the effects of morphology on bed mobility and sediment dispersion were captured at three spatial scales: within morphological units (unit scale), between morphological units (reach scale) and between reaches with different channel morphologies (channel scale). This was achieved by analyzing both reach‐average mobility and travel distance data, as well as the development of ‘mobility maps’ that capture the spatial variability in tracer mobility within the channel. The tracer data suggest that sediment transport in East Creek remains near critical the majority of the time, with only rare large events resulting in high mobility rates and grain travel distances large enough to move sediment past dominant bedforms. While a variable capturing both the magnitude and frequency of flow events within a season yielded a better predictor to sediment mobility and dispersion than peak discharge alone, the distribution of events of different magnitude within the season played a large role in determining tracer mobility rates and travel distances. The effects of morphology differed depending on the analysis scale, demonstrating the importance of scale, and therefore study design, when examining the effect of morphology on sediment transport. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

Morphological dynamics of upland headwater streams in the southern North Island of New Zealand     

Arved C. Schwendel  Ian C. Fuller  Russell G. Death 《New Zealand geographer》2010,66(1):14-32

Short-term channel dynamics of mountain stream reaches in the southern North Island of New Zealand were assessed over two successive 3-month periods using morphological budgeting. Response to floods varies between reaches, even when the catchments were located close to each other and had similar characteristics. The reaches on the Central Volcanic Plateau experienced least morphological change, while streams with steep catchments and migrating planform in the Tararua and Ruahine Ranges showed frequent channel adjustments. Channel response is conditioned by intrinsic variables rendering reaches responsive or robust to the effects of floods, and this is likely to reflect the degree of connectivity between slopes and channels, and reaches.  相似文献   

Sediment loads due to fluvial transport and debris flows during the 2005 flood events in Switzerland   总被引：1，自引：0，他引：1  

Dieter Rickenmann  Anja Koschni 《水文研究》2010,24(8):993-1007

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A simple model of bedform migration     

J. Bartholdy  V.B. Ernstsen  B.W. Flemming  C. Winter  A. Bartholomä 《地球表面变化过程与地形》2010,35(10):1211-1220

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Benefits of design modifications to the Birkbeck bedload sampler illustrated by flash‐floods in an ephemeral gravel‐bed channel     

Nathaniel Bergman  Jonathan B. Laronne  Ian Reid 《地球表面变化过程与地形》2007,32(2):317-328

The benefits of three simple modifications to the design of a Birkbeck bedload slot‐sampling system that has been continuously operating in Nahal Eshtemoa, Israel, since the early 1990s are demonstrated. The modifications include the deployment of a removable slot cover which delays the accumulation of sediment, so allowing sampling at late stages of a flood and, in conjunction with other samplers, extending the period of sampling during a flood wave; inclusion of a slot the size of which is adjustable so that that the probability of sampling the largest clast sizes in transit as bedload can be increased post‐installation, once knowledge is gained about the bedload grain‐size distribution; and a sampler side‐wall door that allows stratification and textural changes within the accumulated bedload to be identified, so promoting intelligent sampling of the deposit for grain‐size determination. Results from seven flash‐floods are presented and discussed, with recommendations for bedload monitoring, particularly in rivers where sediment flux is high and dynamic sediment records are inevitably short because of instrumental limitations. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献