The Loe Bar in Cornwall is a shingle and flint financial institution that separates the ocean from Loe Pool, presenting an uncommon set of challenges in each flood danger administration and environmental safety. Within the following article, Rob Rhyder from measurement expertise and information administration agency Nivus makes an attempt to elucidate how a bespoke monitoring answer was developed for the Surroundings Company (EA) to satisfy the particular necessities of this distinctive location.
Located inside an Space of Excellent Pure Magnificence (AONB) in Cornwall, Loe Pool is fed by the river Cober and plenty of smaller streams. Each the pool and the bar are designated a Website of Particular Scientific Curiosity (SSSI) on account of their distinctive wildlife and habitat.
As essentially the most southerly city on the island of Nice Britain, Helston sits on the banks of the River Cober, upstream of Loe Pool, and has skilled important flooding up to now. Loe Pool is Cornwall’s largest pure freshwater lake, protected by Loe Bar which is roughly half a mile in size. Nevertheless, the bar is geographically distant and uncovered to the ferocity of the Atlantic Ocean, so environmental monitoring gear wants to have the ability to function in harsh circumstances, with out mains energy, and with restricted communications connectivity.
Traditionally, Helston’s flood danger resulted from backing up within the Loe Pool and the River Cober, so alleviation measures primarily included the emergency creation of a reduction channel within the bar. Nevertheless, this was clearly a hazardous operation, so within the Nineteen Eighties and engineered outflow was created within the type of a concrete pipe, put in to function as an overflow for the pool. The pipe allowed extra water to empty from the pool by the bar, however was overwhelmed by river flows throughout excessive circulation occasions. This necessitated costly and invasive over-pumping operations that additionally had a major lead-in time to deliver all of the gear to such a distant web site. As well as, because of excessive tides and excessive climate, the outfall of the pipe was largely blocked by sand and shingle, which needed to be eliminated in periods of flood danger. This course of was inefficient, pricey and time-consuming, so a second engineered outfall was developed.
Engineered outflow answer
The second, extra superior outflow was inbuilt 2020 to largely eradicate the requirement for over-pumping. The extra capability supplied by the second pipe meant that the pool drains by gravity relatively than pricey and carbon-intensive pumping operations. “The brand new outflow featured penstocks, pumps, circulation screens and distant communications, and was developed to supply plenty of essential benefits,” says Will Hancock, Mission Lead on the EA.
Degree and circulation screens have been put in within the River Cober, the Loe Pool and within the new outfall pipe. “This supplied us with the flexibility to observe the location remotely,” Will explains, “which meant that much less web site visits have been needed, reducing mission prices and carbon footprint, and enabling us to answer flood danger in a sooner and extra well timed method.”
The brand new monitoring system was designed to detect the extreme accumulation of water within the pool, in order that the second outflow might be applied when needed. Below such circumstances, an excavator is used to reveal and open the outfall cowl earlier than the sluice gate is opened and the pumps are allowed to take away water from the pool, for discharge to the seaside. Over the past 5 years, the second outfall has been opened on two events.
New circulation monitoring expertise
Previous to the set up of the brand new monitoring system from Nivus, circulation was measured in Helston and within the discharge pipes with a standard Doppler circulation meter, and the failure of one in every of these items supplied the EA with a chance to overview and improve the screens.
Explaining the analysis course of, Will Hancock says: “These measurement devices carry out a critically essential operate. Not solely do they assist handle the Loe Pool to decrease flood danger, in addition they feed information into our flood forecasting mannequin, so it was important that we utilise correct, dependable instrumentation.
The EA has intensive expertise with circulation measurement applied sciences, together with the cross-correlation methodology from Nivus, so it was decided that this could be the suitable answer for the discharge pipes and the river monitor. The important thing benefit to this space velocity circulation measurement method over the devices which it changed is that it gives a three-d circulation profile that’s calculated in real-time to supply reproducible and verifiable circulation values in full or partially crammed channels or pipes. Older Doppler strategies are much less correct as a result of they solely measure 2-dimensional circulation.
The tactic utilises particles, minerals or fuel bubbles which act as reflectors throughout the water physique. Reflections are saved as photos or echo patterns, and in contrast with an additional scan which is performed a number of milliseconds later. Velocity is set by measuring the beam angle of the positions of unambiguously identifiable reflectors. The tactic produces extremely correct readings with out the necessity for extra calibration.
Explaining the background to the choice to spend money on a cross-correlation answer, Will says: “The Nivus gear has been assessed by the EA, and we now run each mounted and transportable variations of the expertise. Nivus can also be a Framework Accomplice, so the process for implementing this answer was comparatively easy, regardless of the particular challenges that this web site introduced.”
Uniquely difficult surroundings at Loe Bar
As a distant location Loe Bar doesn’t profit from quick access to utilities, so it was needed for the monitoring answer to have the ability to function off-grid; photo voltaic/battery energy was subsequently adopted. The answer additionally wanted to be sufficiently rugged to be unaffected by its proximity to the seaside. “Nivus proposed an entire low-power answer, which calculated the facility necessities and specified the photo voltaic era capability that may be needed to make sure steady monitoring in all weathers,” Will explains. “The photo voltaic panels have been fitted at an angle to the ocean, which was much less excellent for energy era, however essential to keep away from potential harm from sand-blasting.”
Particular low-power variations of the Nivus gear have been additionally deployed. For instance, a Nivus NF750 transmitter employs low-power electronics, and consumption is minimised by setting the monitor to sleep, then get up after quarter-hour to take a measurement, after which return to sleep mode.
For redundancy functions, two Nivus CS2 bed-mounted, cross-correlation sensors have been fitted in every of the discharge pipes, and the identical dual-sensor redundancy preparations have been established within the river circulation monitor at Helston, albeit in a cross-channel configuration.
The EA’s normal distant communication gear was put in inside a kiosk together with the transmitter, a multiplexer, rechargeable batteries and a solar energy regulator.
Entry to the monitoring web site can also be restricted. The closest that EA automobiles can entry is 200m away, so any web site visits would necessitate handbook portability for any needed gear. Entry to the monitoring places throughout the pipes can also be doubtlessly hazardous – necessitating respiration equipment and different PPE. Happily, subsequently, the newly put in monitoring system doesn’t require common service or calibration.
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Nivus put in the brand new monitoring system in March 2025, and Will says: “The efficiency to-date has been good – there have been no outages and there have been no necessities for a web site go to. We carried out handbook checks on the screens utilizing a conveyable NivuFlow Stick and they’re monitoring very precisely, representing a major enchancment on their predecessors. Additionally it is comforting to know that we’ve the redundancy measures in place,” he provides.
Trying ahead, Will says: “Given the significance of the Loe Bar as an ecological asset, and of flood administration in Helston, we’re delighted with the efficiency of the monitoring system, and can be making use of for the Loe Pool and Bar to be recognised as a ‘Strategically Essential Asset’.
“On the EA, we’re accustomed to managing distant websites, however Loe Bar might be one in every of our most difficult places, so it has been gratifying to have the ability to set up a sturdy, dependable, and off-grid answer to satisfy the dual targets of environmental safety and flood danger discount.”
