These measurements were taken on a kayak trip from Dittisham to Warfleet Cove and back.
We paddled downstream with the outgoing neap tide and returned with the incoming tide.
The graph below shows a time series of temperature measurements (vertical axis) covering a four hour period (horizontal axis). The gaps show times when the kayak was out of the water.
|12:23||13:00||Dittisham to entrance to Old Mill Creek|
|13:00||13:20||entrance to Old Mill Creek to boatyard|
|13:20||13:33||boatyard to entrance to Old Mill Creek|
|13:33||14:04||Old Mill Creek to Warfleet Cove|
|15:10||16:16||Warfleet Cove to Dittisham|
Within the main body of the river the temperature was mostly relatively constant - between 17.1 and 17.8°C on the upstream leg - and between 16.9 and 17.4°C on the downstream leg - except for a section in the shallows approaching Old Mill Creek.
The highest temperatures were encountered in Old Mill Creek. The Creek was drying out and in parts the navigable channel was less than one third of its high water width. We passed over several sand/mud banks.
The following link shows measurements of temperature overlaid on an interactive map. The colour of the circles are indicative of the temperature and the detailed values can be read by clicking on these circles.
The map below shows the temperatures measured in Old Mill Creek. These were the highest temperatures measured on the trip - reaching above 19°C compared with an average of about 17.3°C in the river.
The image below shows the temperatures measured arriving and leaving Warfleet Cove.
On entering the Cove (with the tide still outgoing) the maxiumum measured temperature was 19.44°C but when leaving the Cove (with an incoming tide) the maximum temperature was 18.69°C.
At the point marked in the map below the inbound temperature was 19.44°C (red circle) and the outbound temperature was 17.94°C; (green circle).
It would seem likely that approaching low tide the water in the Cove would have been warmed by the sun but that as the tide came in it would bring cooler water from the river back into the Cove.