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Water Temperature Measurements - Camel Estuary 2020-07-17

Sample Measurements

A kayak trip was made along the River Camel from Rock to Wadebridge and back.

The trip was undertaken close to Neap Tides. We left Rock at mid-tide and paddled with the tide up-stream. We waited at Wadebridge for High Tide then followed the out-going tide back to Rock. The wind was westerly throughout so the return trip took almost twice as long as the outgoing one.

Below Wadebridge the environment is estuarine with large mud and sandbanks. Above Wadebridge the Camel becomes more river-like.

Padstow Tide Times: 2020-07-17
  Low     08:56 UTC     2.24 m  
  High     14:56 UTC     6.10 m  
  Low     21:27 UTC     2.17 m  

Time Series

The graph below shows a time series of temperature measurements (vertical axis) covering almost a six hour period (horizontal axis). The measurements include times when the kayak was out of the water.

The date-time on the Raspberry Pi was not set at the start, so before setting off, the sensor was warmed between fingers for one minute at a known time. This corresponds to the spike above 35°C at 12:30. This allowed the Raspberry Pi date-time to be adjusted to match that on a GPS.

The horizontal blue arrows show the times when the kayak was out of the water, and the yellow arrows show the times of brief beachings.

    Time Table
  13:12     14:24     Paddle up Estuary from Rock to Wadebridge  
  15:10     15:27     Paddle up River from Wadebridge to high point  
  15:27     15:36     Paddle down River to from high point to Wadebridge  
  15:36     17:36     Paddle down Estuary from Wadebridge to Rock  


By combining these temperature-time measurements with position-time information from a GPS the location of each temperature measurement can be determined. These values can then be plotted on an interactive map.

In the map below measurements are presented as colour coded circles with greens being cold and reds being warm. By clicking on a circle the actual measurements can be examined.

    Colour Table
  16.0-16.5     16.5-17.0     17.0-17.5     17.5-18.0     18.0-18.5     18.5-19.0     19.0-19.5     19.5-20.0     20.0-20.5     20.5-21.0     21.0 up  


The following graph shows the data collected while the sensor was in the water.

The sea surface temperature (SST) at Padstow measured by NOAA satellites was 15.8°C. It is assumed that this is the temperature just off the coast.

The measurements show the water temperature increasing from about 16°C to nearly 21°C above Wadebridge. Presumably the water in the River Camel and the streams feeding it were somewhat warmer than the sea temperature.

Interestingly there are a number of 'spikes' in the measurements taken in the water. The larger of the spikes in the graph were labelled and their time and height above neighbouring values estimated.

Given the time of each spike it is possible to locate the high values on the maps above. Below we show the satellite images in the region of each spike. Note that the satellite images were taken when the tide was at a different level from that encountered on 17 July.


Spikes b, s and t

These spikes all occured adjacent to the sewage works just south of Porthilly Cove.

Spike i

This spike occured adjacent to the sewage works just south of Wadebridge.

Spikes e and f

These spikes occured alongside streams feeding into the estuary.

Spikes m, n, o and p

This set of spikes all occured close together whilst passing through a very shallow area adjacent to reed beds. The satelite images show that several streams feed this area.

Unknown - c and g

Technical Information