A one-way trip, in two kayaks, was made from Exeter Quay, along the canal and then down the River Exe to Exmouth.
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The trip was undertaken on an outgoing high Spring Tide with a tidal coefficient of 105 (i.e. its height was 5% higher than the mean height of all Exmouth Spring Tides).
The wind was a light north easterly.
| Time (UTC) | Event |
|---|---|
| 08:17 | High Tide Exmouth |
| 08:47 | leave Exeter Quay |
| 09:06 | arrive Salmonpool Bridge |
| 09:28 | enter River Exe below St James' Weir |
| 10:21 | arrive Topsham |
| 10:56 | leave Topsham |
| 12:50 | arrive Exmouth |
| 14:24 | Low Tide Exmouth |
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Temperature measurements were made from both kayaks. As both followed similar courses the temperatures were very similar.
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The following links show the temperature measurements overlaid on mapping.
At 10:00 the blue kayak measured a temperature spike, the mapping shows that this occurred adjacent to the Countess Weir Sewage Works. The orange kayak, being further from the outlet, did not measure any increase in temperature.
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At 11:08 both kayaks measured a larger temperature spike. This was in the shallow water above a mud bank where the River Clyst joins the Exe.
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Measurements of salinity were estimated at 10 second intervals using an electrical conductivity probe. The conductivity measurements were temperature corrected and converted to salinity values.
Sea water has a salinity of around 33 ppt (parts per thousand).
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The following link shows the salinity measurements overlaid on mapping.
In the canal (08:47 - 9:06) the salinity is close to zero (< 0.2 ppt).
In the first part of the river, below St James' Weir, the salinity remains low until the right angle bend above Bridge Road. From here the salinity steadily increases.
At 10:00 there is a spike in the salinity - again alongside the outlet from the Sewage Works.
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At Topsham the salinity reached 15 ppt, but after a 35 minute break, it had dropped to 12 ppt - presumably as a result of more fresh water arriving from upstream.
Below Topsham a small excursion was taken up into the mouth of the River Clyst. Alongside Riversmeet House the salinity rose to 28 ppt, and then dropped below 20 ppt as fresher water emerged from the Clyst. On returning to the main channel of the Exe the salinity returned to the value it had been off Topsham (~14 ppt).
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Below Topham the salinity continued to rise, reaching 35 ppt at Exmouth.
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Measurements of turbidity (cloudiness) were taken using a probe which detects light scattered at right angles to a beam of IR light. This reports the frequency output of a photo detector. Higher frequencies indicate higher turbidity.
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The following link shows the turbidity measurements overlaid on mapping.
Opposite the University playing Fields (09:35) it was noticeable the surface of the river was lightly covered in debris - sticks, twigs, dead grasses and a slight slick. The turbidity values increased in this region.
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There was also a measurable peak alongside the Sewage Works.
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Substantially higher values of turbidity were measured over the mud flats at the mouth of the Clyst. Here the water was only just deep enough to float the kayaks.
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Further high values were measured on the approach to Turf Lock - again while paddling over relatively shallow water.
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