Geoscience Reference
In-Depth Information
3, 4 & 5
2 & 6
0.4
0.3
0.2
0.1
0.0
0
100
200
300
400
500
Flow rate (l/s)
Fig. 7 Variation of velocity with flow rate in the study reach
3, 4 & 5
2 & 6
1.2
1.0
0.8
0.6
0.4
0.2
0.0
0
100
200
300
400
500
Flow rate (l/s)
Fig. 8 Variation of dispersion coefficient with flow rate in the study reach
6 Conclusions
The chapter has described the collection and analysis of concentration-time profiles
from a recent series of tracer experiments conducted in a small stream in Edinburgh,
UK. Once converted to a non-dimensional form it was found that all profiles from
both measurement sites had similar shapes. An analysis of the cumulative develop-
ment of the centroid time and variance of the non-dimensional profiles revealed that
the profiles were very similar for non-dimensional times
2, but became less similar
at greater non-dimensional times. The same type of analysis applied to the reach-
average velocity and dispersion coefficient, which were calculated by applying the
method of moments to the non-dimensional profiles, illustrated the sensitivity of
these parameters to the length of the trailing edges of the profiles used in the analysis.
Some insight into the interpretation of the parameters obtained in this way was
achieved. Finally, using an enhanced form of the method of moments that exploited
the similarity of the non-dimensional profiles, it was shown that even severely
truncated profiles could yield valuable information on velocity and dispersion.
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