Geoscience Reference
In-Depth Information
Figure 11.3
(continued)
the source separations of the 216 behavioural models to see what storage and mixing assumptions would
be necessary to reproduce the isotope concentrations in the stream. A number of different hypotheses
were considered. The most successful assumed an effective mixing volume for precipitation and soil
water, and a rate constant for the precipitation water entering the soil to take up silica. The effective
mixing volumes allow for the difference between celerities and velocities. They do not necessarily give
an indication of the total storage associated with each component and, for the GW component, the time
scale of the measurements is too short even to estimate an effective mixing volume.
The results from this model in matching the stream
18
O concentrations is shown in Figure 11.5. The
resulting dynamic effective mixing volumes are shown in Figure 11.6 where it can be seen that this changes
only slowly for the AS soil water component but much more quickly for the DP precipitation component.
The uncertainties in both estimates are quite high, despite the good match to the stream concentrations
shown in Figure 11.5. This study gives a good illustration of the nonlinearity and nonstationarity of
Figure 11.4
Changing contributions of the different components of stream flow in the Bois-Vuacoz subcatch-
ment as a function of storage; results are the median estimates over 216 behavioural models (after Iorgulescu
et al., 2005, with kind permission of John Wiley and Sons).
