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- Stage • Suspended sediment

FIGURE 3.3 High frequency in situ intra-storm measurement of Ed5o: (a) Pynes Cottage on the Jackmoor Brook on 08/04/94, (b) Thorverton on the River Exe on 23/02/94, (c) hydrograph and sampled suspended sediment concentration at Pynes Cottage on 08/04/94, and (d) hydrograph and sampled suspended sediment concentration at Thorverton on 23/02/94.

variation ranges from less than 1 ¡m in the case of the Upper Exe to more than 20 ¡xm in the Exe and Jackmoor Brook, with a study area mean value of 8.8 ¡m. In common with the trends in Ed50 evident in Figure 3.3(a) and (b), the Ed50 "Change" data in Table 3.2 (defined as the difference (¡m) between the last and the first intra-storm measurement) also show a characteristic reduction in Ed50 at the end of each sampling period, with 32 of the 37 storm events showing a reduction in Ed50 relative to that at the start of the storm event. The magnitude of this variation ranges from less than 1 ¡m (Upper Exe) to 28.3 ¡m (Jackmoor Brook), with a study area average value of 7.4 ¡m. It is useful to note that in only one case where an increase in Ed50 was recorded was the value greater than 1 ¡m. This case is associated with the Upper Exe

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