Difference between revisions of "USP61 suspended load sampler"
Dronkers J (talk  contribs) 

(5 intermediate revisions by 2 users not shown)  
Line 1:  Line 1:  
−  This article is a summary of subsection 5.6.2.4 of the [[Manual Sediment Transport Measurements in Rivers, Estuaries and Coastal Seas]]<ref>Rijn, L. C. van (1986). ''Manual sediment transport measurements''. Delft, The Netherlands: Delft Hydraulics Laboratory</ref>. This article describes how the USP61 can be used to determine silt and/or sand concentrations.  +  This article is a summary of subsection 5.6.2.4 of the [[Manual Sediment Transport Measurements in Rivers, Estuaries and Coastal Seas]]<ref>Rijn, L. C. van (1986). ''Manual sediment transport measurements''. Delft, The Netherlands: Delft Hydraulics Laboratory</ref>. This article describes how the USP61 can be used to determine silt and/or sand concentrations. The USP61 is an example of a mechanical instrument. 
==Introduction==  ==Introduction==  
Line 11:  Line 11:  
<math>c\,=G\,/V\,</math>  <math>c\,=G\,/V\,</math>  
−  in which: G= dry mass of sediment (mg), V= volume of water sample (l).  +  in which: <math>G</math>= dry mass of sediment (mg), <math>V</math>= volume of water sample (l). 
The silt and sand transport (in kg/s/m<sup>2</sup>) can be determined as:  The silt and sand transport (in kg/s/m<sup>2</sup>) can be determined as:  
−  <math>S\  +  <math>S = \large\frac{G}{FT}</math>, 
−  in which: F= area of nozzle (m<sup>2</sup>), T= sampling period (s).  +  in which: <math>F</math>= area of nozzle (m<sup>2</sup>), <math>T</math>= sampling period (s). 
The sampling efficiency of the USP61 is strongly dependent on the ratio of the intake velocity and the local flow velocity (hydraulic coefficient).  The sampling efficiency of the USP61 is strongly dependent on the ratio of the intake velocity and the local flow velocity (hydraulic coefficient).  
Line 42:  Line 42:  
* [[Bottle and trap samplers]]  * [[Bottle and trap samplers]]  
* [[Delft Bottle suspended load sampler]]  * [[Delft Bottle suspended load sampler]]  
−  * [[  +  * [[Pump samplers]] 
+  * [[Sand transport]]  
−  
−  
−  
===Further reading===  ===Further reading===  
Line 65:  Line 63:  
AuthorName=Robertihans}}  AuthorName=Robertihans}}  
−  [[Category:  +  [[Category:Coastal and marine observation and monitoring]] 
−  +  [[Category:Observation of physical parameters]]  
−  [[Category: 
Latest revision as of 16:07, 23 August 2020
This article is a summary of subsection 5.6.2.4 of the Manual Sediment Transport Measurements in Rivers, Estuaries and Coastal Seas^{[1]}. This article describes how the USP61 can be used to determine silt and/or sand concentrations. The USP61 is an example of a mechanical instrument.
Contents
Introduction
The sampler consists of a streamlined bronze casting (= 50 kg), which encloses a small bottle (= 500 ml), as shown in Figure 1A. The sampler head is hinged to provide access to the bottle. The intake nozzle, which can be opened or closed by means of an electrically operated valve, points directly into the approaching flow. To eliminate a sudden inrush after opening of the intake nozzle, the air pressure in the bottle is balanced with the hydrostatic pressure prior to opening of the valve. This is accomplished by means of an air bell in a body cavity connecting the bottle and the surrounding stream. After opening of the valve, the air in the bottle can escape through a special airexhaust tube pointing downstream on the side of the sampler head. As a result the hydraulic coefficient is approximately unity during sampling. The filling time varies from 10 to 30 seconds, as shown in Figure 1B. To avoid a circulation flow, the bottle should only be filled for about 75%. The USP63 is a heavier version (= 100 kg) of the USP61. The sampler is manufactured by Rickly Hydrological Company.
Determination of silt and sand concentrations
The silt and sand concentrations are determined as:
[math]c\,=G\,/V\,[/math]
in which: [math]G[/math]= dry mass of sediment (mg), [math]V[/math]= volume of water sample (l).
The silt and sand transport (in kg/s/m^{2}) can be determined as:
[math]S = \large\frac{G}{FT}[/math],
in which: [math]F[/math]= area of nozzle (m^{2}), [math]T[/math]= sampling period (s).
The sampling efficiency of the USP61 is strongly dependent on the ratio of the intake velocity and the local flow velocity (hydraulic coefficient). Extensive laboratory measurements, summarized by Dijkman (1978)^{[2]}, have shown that the hydraulic coefficient varies from about 0.8 to 1.3 depending on the water temperature, sample height above the bed and the nozzle orientation (maximum deviation with flow direction of 20°). For this range a maximum sampling error in the concentration of about 10% may be expected in case of a steady concentration. In the case of field conditions with fluctuating concentrations the inaccuracy of individual samples may be as large as 50%. To obtain a reliable average value in a statistical sense, a large number of samples (about 10) should be collected at each sampling point.
See also
Summaries of the manual
 Manual Sediment Transport Measurements in Rivers, Estuaries and Coastal Seas
 Chapter 1: Introduction, problems and approaches in sediment transport measurements
 Chapter 2: Definitions, processes and models in morphology
 Chapter 3: Principles, statistics and errors of measuring sediment transport
 Chapter 4: Computation of sediment transport and presentation of results
 Chapter 5: Measuring instruments for sediment transport
 Chapter 6: Measuring instruments for particle size and fall velocity
 Chapter 7: Measuring instruments for bed material sampling
 Chapter 8: Laboratory and in situ analysis of samples
 Chapter 9: In situ measurement of wet bulk density
 Chapter 10: Instruments for bed level detection
 Chapter 11: Argus video
 Chapter 12: Measuring instruments for fluid velocity, pressure and wave height
Other internal links
Further reading
 Dijkman, J.P.M. and Milisic, V. (1982) Investigations on Suspended Sediment Samplers. Delft Hydraulics Laboratory and Jaroslav Cerni Institute, Report S410, The Netherlands.
 FEDERAL INTERAGENCY SEDIMENTATION PROJECT. Instructions for USP61, Suspended Sediment Sampler. Minnesota 5541K, U.S.A.
References
Please note that others may also have edited the contents of this article.

Please note that others may also have edited the contents of this article.
