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Sonde and Telemetry Units

Sonde and Telemetry Units

CHASM is pleased to be working with the Environment Agency National Water Quality Instrumentation Service (NWQIS). The aim is to measure water quality parameters along the coast of the Manhood Peninsula, south of Chichester West Sussex, so we can look at some of the environmental factors such as turbidity and water quality that might be affecting crabs and lobsters, but also other biota including plants.

During summer 2020 sonde data loggers enabled the project to measure dissolved oxygen, salinity and turbidity in relation to ‘live’ weather events in Bracklesham Bay.

We have since expanded on the first year of work in Bracklesham Bay through the use of sonde and telemetry units on West Pole and in Fishbourne Channel outside Chichester Marina. This information is gathered by the sonde unit and relayed via a telemetry unit and satellite to the Environment Agency offices in Reading. The intention is to measure dissolved oxygen, salinity, nitrates, turbidity and fDOM coming from the Solent, Chichester Harbour and the east coast of the Isle of Wight. These inputs are thought to work their way along the coast through Bracklesham Bay and Selsey, and may affect lobsters and other species.

For NWQIS this is a feasibility study into the effectiveness of equipment use in a harsh coastal environment. This type of work has not been previously undertaken on the open coast and the CHASM project is a useful vehicle with which to test its effectiveness.

Graphs 1-6 show archived data gathered up to this point in time and the live link to the unit outside Chichester Marina. These are all accessed via a single link. Graph 7 is the new live link to West Pole only.

There are two LIVE LINKS. One in the Fishbourne Channel outside Chichester Marina (Graph 2), and one on West Pole (Graph 7).

They aren’t in quite the right order yet, but this is what the graphs show:

Graph 1: West Pole – this is the archive data gathered from April to Nov 2022 when the unit failed following a severe storm in early November.

Graph 2: FISHBOURNE CHANNEL LIVE LINK this is the link to live data being gathered outside Chichester Marina.

Graph 3: Data logger on the A1 Submarine, Bracklesham Bay. Archived data gathered between late May and early Oct 2021.

Graph 4: Data logger on the Landing Craft Wreck site, Bracklesham Bay. Archived data gathered between late May and early Oct 2021.

Graph 5: Data logger on the Inner Mulberry, outside Pagham Harbour nr Selsey. Archived data gathered between late May and early Oct 2021.

Graph 6: Fishbourne Channel outside Chichester Marina data logger. Archived data gathered between mid-July and mid-Dec 2022.

Graph 7: WEST POLE LIVE LINK: this is the link to live data being gathered on West Pole:

MDC - Meteor Data Cloud (

Using a telemetry unit and sonde is enabling us to observe real time data for up to a year. The length of time is key because it means seasonal variability can be accounted for. The sensor for nitrates will show whether land run off makes its way to the open coast.

There have been three stages to this part of the project so far.

  • During the summer of 2021 sonde data loggers were installed at three sites on the Manhood Peninsula coast - in Bracklesham Bay, outside Medmerry and outside Pagham Harbour.
  • In spring 2022 a sonde and telemetry unit were installed on West Pole, Chichester Bar, just beyond the mouth of Chichester Harbour. Data collection stalled for several months following storm damage to both the sonde and telemetry units. Low tide and calm weather were needed in order to replace both units, but the weather didn't turn our way until April 2023. It is good news that we can report the new link is now in place and working well.  Look out for the new fDOM sensor.
  • In mid-summer 2022 another data logger was installed further up Chichester Harbour and gathered data for three months during the extreme heat of summer 2022 in the main Fishbourne channel outside Chichester Marina. The low oxygen findings were so surprising that a sonde and telemetry unit have replaced the original data logger and now include an fDOM probe.

Many thanks to NWQIS for agreeing to use the site as feasibility study. Follow this link to find out more about NWQIS, the National Water Quality Instrumentation Service

A huge 'thank you' also goes to the following organisations on the peninsula for their ongoing support, and for providing funding to enable the sonde monitoring elements of CHASM to make such good progress:

  • West Wittering and East Wittering & Bracklesham Parish Councils
  • F Glenister Woodger Trust
  • Sussex Kelp Restoration Project

…and to Chichester Harbour Conservancy for doing the hard work of getting the units on West Pole and in Fishbourne Channel installed!

2022 West Pole

2022 West Pole

Shortly after Easter 2022 a real-time water quality monitor was deployed on the West Pole Beacon just outside the entrance to Chichester Harbour. The reason for monitoring this site is to help determine factors affecting crabs, lobsters and other marine life in the area. The site is a meeting point for a number of water bodies, including Chichester Harbour,... Continue Reading »

2022 Itchenor Reach - Chichester Marina

2022 Itchenor Reach - Chichester Marina

During summer 2022 CHASM installed a sonde data logger on one of the wooden markers near Chichester Marina on Itchenor Reach. The aim was to complement the data being gathered by the sonde and telemetry unit on West Pole outside Chichester Harbour. The unit wasn’t able to capture real time data because it wasn't linked to a telemetry unit, but... Continue Reading »

2021 Three Sonde Sites

2021 Three Sonde Sites

In May 2021 the NWQIS department of the Environment Agency kindly loaned the CHASM project an EXO2 Sonde data logger to measure a number of sea water parameters. The aim was to start finding out what is happening in the waters of Bracklesham Bay where the lobster decline was first noticed. To ensure the sonde units would stay in place... Continue Reading »

National Water Quality Instrumentation Service (NWQIS)

National Water Quality Instrumentation Service (NWQIS)

The National Water Quality Instrumentation Service (NWQIS) is responsible for testing, building, calibrating, deploying and maintaining multi-parameter water quality equipment across England. They offer both handhelds, used for spot sampling, and real-time monitors that can be deployed in situ and report live data via telemetry at a specified interval frequency. The data from these devices relates to the physical... Continue Reading »