1. Bedload-transport measurements with geophones
Séminaire GESTRANS Ancien Monastère de Sainte-Croix (26), 3 November 2010
Bedload-transport measurements with geophones
Dieter Rickenmann
WSL - Swiss Federal Research Institute Mountain Hydrology and Torrents Birmensdorf, Switzerland
Danke Vizerektor für Einführung
Geschätzte Damen und Herren
Leibe Kolleginnen und Kollegen

2. 2) Measuring method and test sites 3) Calibration of bedload sensors
Content
1) Introduction
2) Measuring method and test sites
3) Calibration of bedload sensors
4) Results of additional investigations
5) Conclusions and outlook 2

3. Runoff and sediment measuring station
array of PBIS or geophone sensors on check dam
Erlenbach stream (Alptal, CH)
A = 0.7 km²
S = 0.17

4. measuring sites with PBIS or geophone sensor arrays
Erlenbach stream (Alptal, CH): A = 0.7 km², mean channel slope S = 0.17

5. Erlenbach, PBIS measuring site at sediment retention basin
array of PBIS or geophone sensors on check dam

6. PBIS: piezoelectric bedload impact sensor
Example of original PBIS signal, for a 3.8 kg particle passing over a sensor
rolling, center
sliding, right side
Threshold voltage for impulse counting = 0.2 V
time [s]
voltage [V]
Nun zu verschiedenen Aspekten diese Prozesses will ich mich im folgenden kurz äussern
im Einzelnen gehe ich dabei wie folgt vor
Gliederung erläutern.
In Modelle geht es vor allem um Grundzüge dessen was andere schon gemacht haben
Dann um unser Testgebiet und unsere Messungen sowie die Erkenntnis daraus
ergibt das Konzept PROBLOAD und den Ausblick.

7. piezoelectric / geophone bedload impact sensor
fixing of PBIS or geophone sensors on a steel plate
Nun zu verschiedenen Aspekten diese Prozesses will ich mich im folgenden kurz äussern
im Einzelnen gehe ich dabei wie folgt vor
Gliederung erläutern.
In Modelle geht es vor allem um Grundzüge dessen was andere schon gemacht haben
Dann um unser Testgebiet und unsere Messungen sowie die Erkenntnis daraus
ergibt das Konzept PROBLOAD und den Ausblick.
since the year 2000 we use geophone sensors (instead of the piezoelectric sensors)

8. Sediment transport measurements: Erlenbach (Alptal)
Q = 15 l/s
Q = 0.7 m3/s
Q = 10 m3/s

9. coarse sediment along channel bed
Erlenbach
coarse sediment along channel bed

10. Erlenbach, Alptal (Switzerland):
flood events
14 July 1995
25 July 1984

11. Erlenbach, flood event of 25 July 1984: 2000 m3 sediment deposition

12. Pitzbach (A): second test site for PBIS measurements

13. Pitzbach (A), test site for PBIS measurements
water intake
Austria

14. Grain size distributions of sediment at test sites
range of estimated threshold size for detection with PBIS sensor

15. 2) Measuring method and test sites 3) Calibration of bedload sensors
Content
1) Introduction
2) Measuring method and test sites
3) Calibration of bedload sensors
4) Results of additional investigations
5) Conclusions and outlook 2

16. Pitzbach (A): comparison of sediment transport measurements and bedload sensors (hydrophones)

17. PBIS calibration: Pitzbach (A) measurements
PBIS sensor, no. of impulses
Nun zu verschiedenen Aspekten diese Prozesses will ich mich im folgenden kurz äussern
im Einzelnen gehe ich dabei wie folgt vor
Gliederung erläutern.
In Modelle geht es vor allem um Grundzüge dessen was andere schon gemacht haben
Dann um unser Testgebiet und unsere Messungen sowie die Erkenntnis daraus
ergibt das Konzept PROBLOAD und den Ausblick.
sediment volume [m3]

18. PBIS calibration: Pitzbach (A) measurements
= sensor impulses / sediment volume
Nun zu verschiedenen Aspekten diese Prozesses will ich mich im folgenden kurz äussern
im Einzelnen gehe ich dabei wie folgt vor
Gliederung erläutern.
In Modelle geht es vor allem um Grundzüge dessen was andere schon gemacht haben
Dann um unser Testgebiet und unsere Messungen sowie die Erkenntnis daraus
ergibt das Konzept PROBLOAD und den Ausblick.

19. Moving basket system for bedload transport measurements
Erlenbach, sediment
retention
basin,
view upstream

20. New installations at Erlenbach bedload measuring site
rotating crane
metal basket with wire mesh
supporting rail
geophone sensors

21. Moving basket system for bedload transport measurements
Sediment from flood of 4 July 2009

22. Erlenbach: Geophone calibration with moving basket samples

23. Drau river (Dellach, A): Geophone calibration with slot sampler

24. Geophone calibration from several field sites in CH and A

25. 2) Measuring method and test sites 3) Calibration of bedload sensors
Content
1) Introduction
2) Measuring method and test sites
3) Calibration of bedload sensors
4) Results of additional investigations
5) Conclusions and outlook 2

26. Erlenbach (CH), second bedload measuring site
Test of PBIS measurements with two successive rows of sensor arrays

27. Erlenbach (CH), second bedload measuring site
two successive rows with PBIS sensor arrays
bridge

28. Erlenbach (CH), second bedload measuring site
Test of PBIS measurements with two successive rows of sensor arrays

29. Laboratory study: PBIS measurements with particles from Erlenbach
b-axis: cm
b-axis: cm
b-axis: cm
b-axis: cm
No. of sensor impulses
Sample weight of uniform grains [kg]

30. Laboratory study: PBIS measurements with particles from Erlenbach
Normalized cummulative frequency curves.
Top: uniform material (4 cm) with different sample weights.
Bottom: 4 different grain sizes with 2 sample weights for each size class

31. 2) Measuring method and test sites 3) Calibration of bedload sensors
Content
1) Introduction
2) Measuring method and test sites
3) Calibration of bedload sensors
4) Results of additional investigations
5) Conclusions and outlook 2

32. Advantages of PBIS measuring system
- robust technique requiring only very few maintenance
- continuous measurement of bedload transport intensities
- detection of beginning and ceasing of bedload motion
- relatively low costs for measuring equipment and necessary constructions at measuring site
- for longer observation periods and larger bedload volumes a reasonable accuracy is obtained for the calibration relationships (considering natural variability of bedload transport in mountain streams) 2

33. Disadvantages of PBIS measuring system
- calibration of the system is necessary
- no information on particle sizes in transport can be obtained
- there is a limit for the lower critical particle size which can be detected
- influence of hydraulic conditions and sediment properties on calibration are almost unknown at present
- changing flow intensities are likely to change the size distribution of transported bedload particles (resulting in non-linear calibration relations, if such effects are not averaged out) 2

34. Outlook: WSL – GESTRANS cooperation project
Objective: Comparison of two complementary indirect
bedload transport measuring approaches:
- Geophone measurements as applied by WSL
- Hydrophone measurements as applied by Université Joseph Fourier, LTHE, Grenoble
Possible sites for comparative measurements:
- Erlenbach stream (operated by WSL)
- Draix experimental catchment (Cemagref)
Experimental flume (Cemagref, LTHE)
Possible travel support:
- Germaine de Staël program (submitted proposal) 2

35. Bedload-transport measurements with geophones
Séminaire GESTRANS Ancien Monastère de Sainte-Croix (26), 3 November 2010
Bedload-transport measurements with geophones
Thank you for the attention
Danke Vizerektor für Einführung
Geschätzte Damen und Herren
Leibe Kolleginnen und Kollegen
Dieter Rickenmann
WSL - Swiss Federal Research Institute Mountain Hydrology and Torrents Birmensdorf, Switzerland

36. piezoelectric / geophone bedload impact sensor
fixing of PBIS or geophone sensors on a steel plate
Nun zu verschiedenen Aspekten diese Prozesses will ich mich im folgenden kurz äussern
im Einzelnen gehe ich dabei wie folgt vor
Gliederung erläutern.
In Modelle geht es vor allem um Grundzüge dessen was andere schon gemacht haben
Dann um unser Testgebiet und unsere Messungen sowie die Erkenntnis daraus
ergibt das Konzept PROBLOAD und den Ausblick.