Manhood Peninsula Partnership > Projects > CHASM > Sonde and Telemetry Units > 2021 Three Sonde Sites > Three sonde sites initial observations « you are here

Three sonde sites initial observations

Initial observations on the 6 weeks of data from the Landing Craft (Medmerry) and Inner Mulberry (Pagham) sites, and the 12 weeks of data from the A1 submarine site (Bracklesham Bay).



Location – south east of Chichester Harbour entrance

  • This site has the biggest diurnal in temperature and this is also reflected in the diurnalling dissolved oxygen (DO). The diurnal in DO is a result of algae. When the temperature gets 'too hot' for the algae they begin to die off and we see less of a diurnal in DO. This pattern is seen across all 3 sites, during periods of higher temperatures.
  • Events that took place on the 06/08/2021-10/08/2021 show a suppression in DO below 100%. Although it appears to be a small suppression, it is still significant considering the size and dilution factor of the sea. However, this could be caused by wave action, and the sediment having a BOD (Biological Oxygen Demand) associated with it.



Location – near shore adjacent to Medmerry entrance

  • Hardly any diurnal variation here, pretty flat lines indicating good water quality probably the best out of the three.



Location: nearshore adjacent to Pagham Harbour entrance

  • This site has higher DO than the other sites, roughly 15% higher.
  • Events on the 23/08/2021-26/08/2021 and 05/09/2021-11/09/2021 show spikes in temperature and drops in DO. This could be CSO's firing off OR wave action? It is worth checking whether releases from CSO's took place.

There is a lot more sedimentation disturbance at the A1 site and landing craft site.