Category: Guide 1

Who is the decision maker when it comes to managing the beach?

Who is the ultimate decision-maker? 

The section of beach within the scope of this discussion is wholly within the North Wirral SSSI [site of special scientific interest] (1) Consequently, any activity that affects the habitat must be approved in advance by Natural England. Specifically, it is an offence to carry out any activity that may likely damage the SSSI without consent from the relevant conservation agency. (2) Furthermore the site is also designated as part of the Dee Estuary Special Area of Conservation which grants still higher levels of protection to any habitats classes as Annex 1 under that citation.  

Why has the management of Hoylake Beach been halted?  

Natural England’s formal Assent that permitted the management of Hoylake Beach expired on the 31st March 2021. Prior to that, at the end of the 2019 season, they advised against spraying or raking They have not renewed the licence, consequently, it is currently illegal to rake or spray the beach. [3]

What needs to happen before and raking of the beach can start?  

Natural England have indicated that it might be possible to replicate the approach they have adopted at Southport, ie. identify an area of the foreshore that can be retained as a managed amenity area, however, they will not agree to anything prior to a comprehensive botanical and geomorphology study. This will identify the least harmful location and determine if the damage resulting to nationally important habitat is justifiable. Nothing can happen without Natural England’s specific say-so.

Issues to consider:

If the council were to resume raking without first obtaining permission from Natural England, they would be liable to prosecution and fines.

EVIDENCE:

Link to the citation for the North Wirral Foreshore SSSI https://designatedsites.naturalengland.org.uk/SiteDetail…

Link to the Environmental Law covering SSSIs http://www.environmentlaw.org.uk/rte.asp?id=303

Link to a letter confirming that Assent to rake/spray Hoylake beach has been withdrawn by Natural England, and evidence that raking is likely to result in prosecution of the Council https://democracy.wirral.gov.uk/…/Natural%20England…

In the 1600s, the Hyle/Hoyle “lake” was a channel, 30ft deep at the Dovepoint end, and 15ft deep at the Hilbre end. It was deep enough for the largest ships using the coast to moor at low water. Silt from mostly the Dee but also the Mersey was deposited in the channel over time and it gradually filled. By the late 1800s there was still enough water close off shore to allow the substantial Hoylake fishing fleet to anchor there. (1)

When the promenade was built, only the eastern part of the channel was water at low tide, but there was still a channel around 200m from the promenade, filled with water twice a day and protected the promenade from sand blowing in from the East Hoyle bank. (2) 

That channel continued to fill with silt, though water with a heavy load of silt would still arrive from east and west each tide. This too acted as a barrier to windblown sand, though the beach level continued to rise and become flatter.

Today the beach level measured at 200m offshore is around 6-7m higher. It is almost flat (a 1 in 400 gradient). Sand has finally covered over the silt, at least to level with the Old Baths, and there is no gutter to bring silt in from the Dee. The mean high tide mark is retreating seaward at an astounding 7m a year and the upper beach is now above the astronomical high tide mark (which is why dune plants are able to establish).

As sand continues to blow in, some of it will be trapped by the seaward edge of the green beach which will rise into a ridge, further protecting the upper beach from seawater. (3)

The height and position of those dunes will be determined by the relative contribution of sand delivery and tidal scour but an equilibrium will be found. They will start on the outer edge of the main vegetation line and adjust outwards. A dune slack will form behind.

References

1. Hoylake’s fishing fleet at anchor, dunes and bathing machines prior to the promenade, Young, D, More pictures from the past. 
2. Children paddling in the Hoyle Gutter, showing the proximity if water and the steep profile of the beach Young, D Ibid. 
3. Sand dune formation and succession: Short video tutorial Universities of Cambridge/Derby 

More on saltation and how slipways give us an insight into what will happen if we do not have a solution to sand-blow

The attached diagram explains why at Hoylake, most aeolian (by wind) transport of sand is by saltation and what determines how much sand can be carried by the process. Most people will have seen saltation in action or felt it on their shins if out on the beach. Here is a video from Hoylake beach on Youtube 

The following is noteworthy:

• the grains seldom reach more than 25cm above the beach before gravity pulls them back down, though in extreme conditions 1.5m jumps are known. This has implications for the design of artificial or natural on beach barriers to prevent sand from reaching the promenade and is why saltation only gives us issues when the promenade is over-topped or the sand can blow up a slipway
• A phenomenal amount of sand can be transported like this. 10.9 metric tons of sand per meter per day can be delivered in an onshore Force 8-9 gale. That is 5.5 metric tons per minute across the zone from Kings Gap to the Lifeboat station in a NW gale if the beach is dry
• Anything that lowers the drag force of the wind or increases the lift needed to overcome gravity, will reduce the amount of sand transported. The energy to raise each grain of sand up a slipway is about 0.6J [0.004g per grain and a 1.5m rise] Consequently the carrying capacity of the wind is greatly reduced on slipways.

In the last few days a steady, but not excessively strong WSW wind has been blowing more or less parallel to the promenade, with frequent rain showers damping down the saltation process. There is a relatively narrow band of free sand (compared to the huge East Hoyle Bank), close to the sea wall, and this has been able to saltate sand up the new slipway by the lifeboat station. The outcome is the familiar build up of sand around the Hoyle Rd slipways and near the Parade School wall [see the posts below for examples]

Now imagine this was the whole width of the beach providing sand and there was less than 20cm from the sand to the top of the wall, rather than the need to carry sand up the slipway and lose most of its lifting power. This video is a clue – from when a limited overtopping occurred in two small sections, at the King’s Gap steps and the Alderly Rd slipway.  .

How wind moves sand

At Hoylake, most windblown sand is moved by three main methods which depend on the wind speed and especially the size of the sand grains.

At Hoylake,  >95% of sand moves by saltation a sort of hopping action – when a sand grain “hops” and when it lands dislodges more grains and they dislodge more, until a cascade of sand starts moving in the wind a few cm above the beach – see Figure 1

Saltation can start with wind speeds as low as 5m/s (11mph) but if the beach is wet, after a tide or rain, it takes stronger wind

s to start the sand moving.

If the prevailing winds blow over a large expanse of sand, there is more chance of it drying out and the conditions for saltation to occur.

Once in motion, the saltating sand will continue moving until:

• The sand particles are in the lee of a raised object
• The wind drops
• The sand particles meet an uphill gradient that is too steep for the wind
• The sand particles hit a wet patch or an area bound with silt or a salt crust

Increasing average winds, a greater expanse of sand or less frequent coverage by the tide will increase the amount of sand delivered to the promenade.

Why there is a greater risk of sand blowing onto the promenade

• In the 1660s when the 1st map in figure 2 was created, the Hoylake lake was less of a lake and more of a channel, 5m deep at the Hilbre end and 10m deep at the Dovepoint end.
• It was used as a sheltered [by the East Hoyle bank] deep-water anchorage
• Kings Gap, was a small and managed gap in the huge dune system on N Wirral that allowed convenient access to horse-drawn traffic.
• Tidal forces have redistributed the sands of the E.Hoyle since the last Ice Age, gradually filling in the Hoyle “lake” The second map is from an 1899 survey and shows that the channel was now a gutter reaching about ½ the original length
• As recently as 10 years ago the mud and silt of the Hoyle Lake was easy to encounter just by walking seawards, though the permanent gutter had gone.
• Before about 1850, there was only around 70-700m of exposed sand that could saltate offshore, but that was enough to build dunes. Figure 3
• Even when the “Lake” filled the wet sand and mud of the remnant gutter protected the promenade from the bulk of sand blow in from the East Hoyle bank because it broke the sand transport pathway for saltation.
• Now there is no protection from the vast expanse of the East Hoyle bank’s wind-blown sand and a direct sand transport pathway has developed
• Mean High water mark is retreating at up to 75m/decade, so more of the bank is dry more often
• Climate change makes extreme weather events more likely.

Consequently, we can expect a lot more sand to be delivered a lot more frequently.

How much sand has arrived (and where is it)

One of the benefits of undertaking that enormous analysis of the LiDAR data is that its now possible to examine the changes to the beach in huge detail.

• You can see from the first graph that the highest build-up of and isn’t close to the promenade – it’s 100-200m out on the beach. This explains why it’s no longer a muddy slippery, impassable quagmire out there – that’s under close to a meter of fresh sand
• The second graph shows build-up is much greater at the RNLI end of the beach (and this isn’t the effect of the old baths – it has happened out way past them too).
• Looking at the profiles of different locations over time, the areas which are accreting are mostly accreting at a steady rate i.e. the changes we have seen are still going on and the beach is getting higher and higher
• HOWEVER there are locations (currently in the model as linear projections based on accretion 1985-2020 that actually fit better as passing a tipping point and now are accreting much more rapidly. This means there might actually already be a lot more sand arriving now, and the rate of delivery is accelerating. These are further out on the beach and may well be a foretaste of things to come.

Studies on the control of Spartina have shown mechanical removal leads to a 42.8% increase in plant density in subsequent growing seasons compared to control areas that were left unmanaged. [1] This is because this grass propagates via underground rhizomes and any activity which fragments and redistributes those rhizomes will increase the rate at which it can spread compared to natural expansion. 

How could Spartina be controlled?

• Chemical spraying will slow the expansion of Spartina, though the effect is short-lived and recovery to 100% of former density occurs within 1-2 years. (1,2)
• Smothering with dredged substrate or covering with plastic sheeting for a complete growing season has been shown to be effective in controlling Spartina (3,4)
• Complete removal of substrate containing the rhizomes which extend 30-40 cm underground is an effective treatment [2]

What will happen if we do nothing?

As noted in https://www.facebook.com/groups/353912892854904/posts/353920626187464 the Spartina growth on the North Wirral foreshore is constrained within a zone with specific conditions of salinity and silt delivery. That zone is moving as the accretion continues. Now that that raking and spraying has stopped favouring Spartina over its competitors, it is more or less irradicated from the upper beach. That process will continue to happen as the beach profile changes.

References

1. First record of Spartina alterniflora in southern Africa indicates adaptive potential of this saline grass 

2. A systematic review of the effectiveness of management techniques used in the control of invasive estuarine cordgrass Spartina species 

3 The Effects of Smothering a Spartina alterniflora Salt Marsh with Dredged Material 

4. Hammond, M, 2001, The experimental control of Spartina anglica in estuarine salt marsh #spartina

Who is the ultimate decision-maker? 

The section of beach within the scope of this discussion is wholly within the North Wirral SSSI [site of special scientific interest] (1) Consequently, any activity that affects the habitat must be approved in advance by Natural England. Specifically, it is an offence to carry out any activity that may likely damage the SSSI without consent from the relevant conservation agency. (2) Furthermore the site is also designated as part of the Dee Estuary Special Area of Conservation which grants still higher levels of protection to any habitats classes as Annex 1 under that citation. 

Why has the management of Hoylake Beach been halted? 
Natural England’s formal Assent that permitted the management of Hoylake Beach expired on the 31st March 2021. Prior to that, at the end of the 2019 season, they advised against spraying or raking They have not renewed the licence, consequently, it is currently illegal to rake or spray the beach. [3]
What needs to happen before and raking of the beach can start? 
Natural England have indicated that it might be possible to replicate the approach they have adopted at Southport, ie. identify an area of the foreshore that can be retained as a managed amenity area, however, they will not agree to anything prior to a comprehensive botanical and geomorphology study. This will identify the least harmful location and determine if the damage resulting to nationally important habitat is justifiable. Nothing can happen without Natural England’s specific say-so.

Issues to consider:

If the council were to resume raking without first obtaining permission from Natural England, they would be liable to prosecution and fines.

EVIDENCE:

Link to the citation for the North Wirral Foreshore SSSI 
Link to the Environmental Law covering SSSIs 
Link to a letter confirming that Assent to rake/spray Hoylake beach has been withdrawn by Natural England, and evidence that raking is likely to result in prosecution of the Council 

Salt marsh or sand dune? What the plants can tell us about the emerging habitats at the Hoylake foreshore.

Over the past two years, I’ve completed 5 survey visits in total looking at the plant species that grow across Hoylake beach and their relative abundance. Using that very same survey data, I looked at Ellenberg values for salt. These values indicate how tolerant any given plant species is to salt, for example, a species that has a really low Ellenberg salt value of 0 is one that is entirely intolerant to salt. By comparison, species with high Ellenberg salt values at around 7 to 9 indicates that the species is highly adept to survive in brackish environments, like Spartina and Glassworts.

In early to mid-successional saltmarshes, these are highly brackish environments rich in salt, and the species that live in them indicate that by having high Ellenberg values for salt, just like Spartina (Ellenberg = 7) and Glassworts (Ellenberg value = 9). By comparison, species that live across other coastal habitats, namely sand dunes, that are not regularly inundated by the sea, tend to have very low Ellenberg values. Were Hoylake transitioning into saltmarsh from what was a previously raked beach, the Ellenberg values for salt we would anticipate seeing would be very high. However, were Hoylake transitioning into a dune system, separated from high tides, Ellenberg values would be very low and would probably decline over time.

This is exactly what we see at the moment at Hoylake. Average Ellenberg values for salt are now not only incredibly low currently (1.5), but they have declined over the past two years and look to be continuing to do so. In addition, plants like Sand Couch and Lyme-grass, sand dune pioneer species, have significantly increased in their abundance across the beach in just two years. Other sand dune specialists not ever found in any recognised saltmarsh community are also now established and widely distributed across the beach, including Marram and Sea Spurge.

Although some people may think that the Hoylake foreshore might be transitioning to saltmarsh and would not develop into a dune system, the developing vegetation is telling a very different story.

Strictly speaking, we mean the area covered by the study area covered by LiDAR measurement since 1985 (see the 1st image), though there is benefit in talking about Meols, which is like Hoylake 40-50 years ago, and red Rocks to West Kirby. Both areas were part of the same original dune system, before the north shore was encased in concrete

The Special Area of Conservation (Internation Protection and purple hashed)) cover The King’s Gap, Alderley and RNLI Slipways, but not Trinity, or Hoyle.