Bedload entrainment, travel lengths, step lengths, rest periods—studied with passive (iron, magnetic) and active (radio) tracer techniques

Bedload entrainment, travel lengths, step lengths, rest periods—studied with passive (iron,... This paper reports results from bedload transport investigations with active (radio) and passive (iron, magnetic) tracers in the Lainbach, a step‐pool mountain river, in Bavaria, Southern Germany. The spatial distributions of the iron tracers after flood events can be best described by exponential or Gamma distributions. There is some indication of a tendency of size‐selective transport of the iron tracers, but there is also a considerable amount of scatter in the correlations between weight (size) and travel length owing to the masking influence of other variables, such as the shape of the particles and different positions in the river bed. The experiments with artificial magnetic tracers showed that elongated pebbles (rods) had the longest mean transport distance, platy ones (discs) remained relatively close to the starting points. The particles from the pool showed the greatest transport lengths and a 100 per cent chance of being eroded. The Pebble Transmitter System (PETSY) consists of transmitters implanted into individual pebbles, a computerized receiver, a stationary antenna system with an antenna switchboard, and a data logging system. The particles do not move continuously but in a series of transport steps and non‐movement intervals. A single value for a given size‐class is not adequate to describe the critical conditions of entrainment under natural circumstances. A probability approach is much more suitable. The critical unit discharges (total discharge divided by active channel width) along the measuring reach are dependent on river bed morphology. In the steps bedload needs higher unit discharges to be entrained. Once entrained, the transport of bedload is stochastic in nature and the single particle transport is controlled by the step lengths and the duration of rest periods. The distributions of both parameters can be approximated by exponential functions. Applying the stochastic concept proposed by Einstein the mean values of the random variables (step length) and (duration of rest period) measured with the PETSY technique were used for the simulation of spatial distributions of bedload particles from point sources. More field and laboratory data are needed to include varying flow and roughness conditions with tracers representing different particle characteristics. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Earth Surface Processes and Landforms Wiley

Bedload entrainment, travel lengths, step lengths, rest periods—studied with passive (iron, magnetic) and active (radio) tracer techniques

Loading next page...
 
/lp/wiley/bedload-entrainment-travel-lengths-step-lengths-rest-periods-studied-G5CHpeF0hz
Publisher
Wiley
Copyright
Copyright © 1992 John Wiley & Sons, Ltd
ISSN
0197-9337
eISSN
1096-9837
DOI
10.1002/esp.3290170204
Publisher site
See Article on Publisher Site

Abstract

This paper reports results from bedload transport investigations with active (radio) and passive (iron, magnetic) tracers in the Lainbach, a step‐pool mountain river, in Bavaria, Southern Germany. The spatial distributions of the iron tracers after flood events can be best described by exponential or Gamma distributions. There is some indication of a tendency of size‐selective transport of the iron tracers, but there is also a considerable amount of scatter in the correlations between weight (size) and travel length owing to the masking influence of other variables, such as the shape of the particles and different positions in the river bed. The experiments with artificial magnetic tracers showed that elongated pebbles (rods) had the longest mean transport distance, platy ones (discs) remained relatively close to the starting points. The particles from the pool showed the greatest transport lengths and a 100 per cent chance of being eroded. The Pebble Transmitter System (PETSY) consists of transmitters implanted into individual pebbles, a computerized receiver, a stationary antenna system with an antenna switchboard, and a data logging system. The particles do not move continuously but in a series of transport steps and non‐movement intervals. A single value for a given size‐class is not adequate to describe the critical conditions of entrainment under natural circumstances. A probability approach is much more suitable. The critical unit discharges (total discharge divided by active channel width) along the measuring reach are dependent on river bed morphology. In the steps bedload needs higher unit discharges to be entrained. Once entrained, the transport of bedload is stochastic in nature and the single particle transport is controlled by the step lengths and the duration of rest periods. The distributions of both parameters can be approximated by exponential functions. Applying the stochastic concept proposed by Einstein the mean values of the random variables (step length) and (duration of rest period) measured with the PETSY technique were used for the simulation of spatial distributions of bedload particles from point sources. More field and laboratory data are needed to include varying flow and roughness conditions with tracers representing different particle characteristics.

Journal

Earth Surface Processes and LandformsWiley

Published: Mar 1, 1992

References

  • Size selective entrainment of bed load in gravel bed streams
    Ashworth, Ashworth; Ferguson, Ferguson
  • Interrelationships between bed morphology and bed material transport for a small gravel‐bed channel
    Laronne, Laronne; Carson, Carson

You’re reading a free preview. Subscribe to read the entire article.


DeepDyve is your
personal research library

It’s your single place to instantly
discover and read the research
that matters to you.

Enjoy affordable access to
over 18 million articles from more than
15,000 peer-reviewed journals.

All for just $49/month

Explore the DeepDyve Library

Search

Query the DeepDyve database, plus search all of PubMed and Google Scholar seamlessly

Organize

Save any article or search result from DeepDyve, PubMed, and Google Scholar... all in one place.

Access

Get unlimited, online access to over 18 million full-text articles from more than 15,000 scientific journals.

Your journals are on DeepDyve

Read from thousands of the leading scholarly journals from SpringerNature, Elsevier, Wiley-Blackwell, Oxford University Press and more.

All the latest content is available, no embargo periods.

See the journals in your area

DeepDyve

Freelancer

DeepDyve

Pro

Price

FREE

$49/month
$360/year

Save searches from
Google Scholar,
PubMed

Create folders to
organize your research

Export folders, citations

Read DeepDyve articles

Abstract access only

Unlimited access to over
18 million full-text articles

Print

20 pages / month

PDF Discount

20% off