Falmouth Field Course 2017

The views and opinions expressed on this website are not necessarily those expressed by the University of Southampton or the National Oceanography Centre. They are purely representative of the authors of this website.

Transect 1

Transect 1 was taken at centre of the River Fal which is relatively narrow with a depth of ~17m in the centre. During the first transect one of the two engines broke down therefore the transect was relatively short and taken from N/S, not across the river. This can be seen in the ship track at the start where the vessel takes a circular path before continuing southward. Constant flow rates northward ranging between 0.2-0.36 ms-1 can be seen on the velocity cross section, this is representative of the flooding tide.

ADCP Transects

Transect 2

The second transect was taken further south where the river fal meets the fal estuary. At the start of the transect surface flow southward can be seen which is likely due to the surface discharge from the pill creek located to the left of the start on the transect. Weaker northward flows than previous can be seen on the velocity cross section where northward flows have slowed to ~0.05-0.1 ms-1 representing the start of the turning tide. Slightly stronger deep inflow and surface flow on the right hand side can be seen.

Transect 3

Transect three was taken along the middle of the estuary towards Mylor Creek. As can be seen on the velocity cross section the deepest part of the cross section was ~30m. In reference to the ship track and velocity cross section it is clear that slack water has been reached as strong southward outflow can be observed between 0.08-0.3 ms-1 and weak surface inflow ~0.9 on the right hand side. The tide is switching from the flood to the ebb.  

Transect 4

The final transect was taken near the mouth of the estuary where a large tributary meets the estuary. When referring to the ship track it clear that the ebbing tide is strengthening as southward flow rates are increasing. On the velocity cross section the strongest flow occurs in the surface 7m on the right hand side ~0.2 ms-1. The middle of the estuary is still showing slow flows of ~0-0.09 m/s as the tide is in the early stages of turning.  

Intro

Four ADCP transects were taken on the Bill Conway travelling from King Henry pontoon southward down the River Fal and into the Fal Estuary. Transects were taken between 12.40 and 14:25 UTC with high tide at 14:00. Therefore we could observe the turning of the tide from a flooding northward flow to the ebbing southward flow. The ADCP could only measure to depths of ~16m, and so deeper areas have no data. The below discussion section includes a velocity cross section and ship’s track plot for each of the four trnasects.

Table 1.  ADCP transect times and locations