[Speaker: Tracey Miller-Armstrong]

So we've got consultant BMT on the line with us today. So we've got Christian joining us and he's going to now provide a presentation and he's going to talk to everybody about the adaptation pathways assessment. So I'm going to hand it over to Christian now. Thanks for joining us. And he's going to present his presentation.

Christian, I actually think you're still on mute.

[Speaker: Christian Taylor]

Thank you. Hello everybody. My name is Christian Taylor. I'm a coastal engineer with BMT consulting firm. So I'm going to share my screen now and show your presentation on the adaptation pathways. So could somebody let me know if they can see the presentation?

Yep, that one's sharing for us now. Thanks, Christian.

OK, great. Looks a bit different to the other day.

So, so we got a picture of the Victoria's brilliant coast guidelines process there. So adaptation pathways planning is, as Tracy was saying, it's about making short term decisions which are in line with the long term adaptation of the site because the climate is changing and sea levels are rising.

And that means that in the future, things that work today are not going to work.

And as we plan for how we adapt to the, to the changing climate and, and the rising sea level, we, we need to understand those changes and we need to avoid making decisions that are maladaptive. That means that they will trap us in a situation where the risk get gets higher rather than lower.

So the Victoria's resilient Coast guidelines is a, is a, a process for making these, these adaptation planning decisions which we've, we've followed for this study. The, the process starts with, well, we start with scoping and preparation.

Stage 2 is very important, understanding the values and the visions and objectives for the site. So understanding what it is that you know, the what's there, what people care about, how people use this site and how we want to use it in the future.

Then we we look at the coastal hazards.

So that's principally erosion and inundation can also be sort of sediment movement and saltwater intrusion, but erosion and inundation related to sea level drop rise are the main ones.

Then we look at how those coastal hazards impact on the different values and uses of the site. This is stage 4.

Now stage 5 is what are the, you know, what can we do about it? The adaptation actions, what, what things are available for us to, you know, to, to mitigate those hazards and the, and the risks.

And then to order those into sort of a pathway, an implementation plan over time that that manages, manages the risk and doesn't lead us down a pathway where we end up with a with a higher level of risk. So ultimately, it's about having a road map for how the adaptation is going to unfold over the next sort of 70 or 50 to 100 years. And then we can use that to inform the short-term decision making.

So the site that that we've looked at is the Lang Lang Foreshore Reserve and principally the caravan park as as shown here going from Jetty Lane standing about I think it's about 800 metres to the South along the the shore of Western Port.

The we, we did have a discussion with the, the, the committee of management and the caravan park managers, some of the local land managers and some of the people at the caravan park about what was really valued at this site. And these are some of the the key messages we heard.

Just summarise briefly here that the beach was important, walking, fishing, swimming, general passive recreation on the beach with the caravan park, camping and picnicking in proximity to the water was, was an important value.

And I think it's, it's a really unique offering there that you can camp right on the edge of the of the water there. The public boat ramp is obviously very popular for the small craft kayaks and jet skis. There's a range of community uses. We heard about football club training, swimming, fun runs, general gatherings, family gatherings, school camp, use of the area, horse riding and CFA training.

There's a number of privately owned structures, boat sheds, cabins, vans with annexes which are in the caravan park and they're, they're highly, highly valued. And there's some heritage aspects to the site with, you know, a previous swimming pool and pier location.

And of course, another important, I guess not a community value, but a, environmental value is the Western Port Ramsar wetland and that being a important habitat for migratory birds.

In the coastal hazard assessment, which is the next phase, we reviewed all the the different classifications of coastal hazards, and we've identified the ones that are important at the site.

This probably won't come as a surprise to anyone who is familiar.

The short-term erosion based on, you know, sort of cyclic erosion recovery that that a lot of beaches get is not so much of a factor here. It's really though there's a long-term recession in the areas that are unprotected by sea walls. You do have this sort of long-term progressive eating away of the coast without a lot of recovery. So that's very important.

The other ones that are that are probably the highest importance are the coastal inundation. And we there are, we sort of break that into two types of of hazard. There's storm tide inundation and that's to do with waves and, and, and, and storm events where you get a sort of a surge and that that happens just during what you know, that happens episodically, it happens sometimes and then it it goes away again.

There's permanent inundation, which is where that's your regular hot spring, high tides that getting a little bit higher every year. And with sea level rise, of course they're going to accelerate and, and get even higher. So there's two different causes to inundation, but often, often they combine. You have a high tide and you have a storm surge at the same time causing inundation, which means flooding water into the caravan park.

Potentially saline intrusion might be a factor for some buried assets. We get saltwater coming in through the groundwater could impact on the septic systems.

Estuary dynamics and offshore sediment transport dynamics are two of the other hazards that are probably less important for this site. But the ones in red, they're, they're the ones that we need to focus on and in particular inundation, which I'll talk the most about.

So we have in analysing the inundation patterns of this site, we've looked at three different levels of inundation flooding. And these are related to discussions we had with the park managers and others users about what, what's, what, what does the park experience now. And, and this provides a good benchmark for our, for our analysis.

So the lowest level is what we're calling the nuisance flooding. And that's just where you get a few waves over topping the seawall. nd the picture on the top there shows it from a, from a drone. There's very, the water generally drains across the lower sites there and into the drains along the road. And it doesn't really cause much of a problem there's, there's very little disruption. And what we heard was that that's occurring almost monthly at the moment.

The next level up we've termed minor flooding. This occurs when a larger volume of water comes over the top of the the sea wall. So you've got larger waves or a higher water level or both. And the water coming in then sort of overwhelms the drainage capacity along the road and you get sea water pooling in low lying areas and that can cause the closure of the road. And this is of course at the North End of the caravan park where the where the gate is.

And can, can, can be a problem for access restrictions can be a problem for access. And this occurs, we understand, around six times per year. And the final category is the major flooding.

This is much deeper flooding can go over the floor of the toilet blocks, the Rotunda, the barbecues and the laundry and hence it can cause, you know, quite a bit of damage or and there can be, you know, clean-up costs associated with it. Access is definitely cut through the road and the gate area.

The flooding often extends into the paddock behind the caravan park and going back through the record, we've found two instances of that July 2023, which is in the bottom picture. It's not a great photo, it's pinched off the caravan park Facebook page. But they're also, we believe that a similar event occurred in 2009. So we can say that's occurring about once every 10 to 15 years at the moment. That's the major flooding.

So remember those terms, nuisance flooding, minor flooding and major flooding because I'll be talking about those as we go forward. So what's causing the flooding?

This the mechanisms, it's a combination of, of a number of things. Principally it's a sort of a, a storm tide level, which is a, you know, which is a combination of a whole lot of factors coming together to push the water levels up.

We have surge, storm surges or, or, or wind set up in, in Bass Strait that can that we get a higher water level in Bass Strait, maybe 20 or 30 centimetres higher than normal and that propagates up into Western Port Bay.

Then we have the, the high tide in the Bay and we have the wind blowing westerly winds blowing across from sort of Hastings across the, the upper N arm to the long fetch and all of that, that, that the wind will actually push the water towards the eastern side of of the Bay and elevating water levels and, and creating waves which as well as elevating water levels.

We've now got waves which break on the seawall and the splash then comes over the top and that's the overtopping water. And it it will then flow down into the lope parts of the caravan park as shown here. So that's the sort of the common mechanism that's occurring at the moment. In the future, as sea level rises, this will begin to occur. And this is what I'd call storm tide over the wall.

And the key difference you'll notice here is that the, the still water level, which is the, the median water level, I guess of between the peaks and troughs of the waves is now over the top of the seawall and the ground level.

So rather than getting like a splash coming in and that episodic waves breaking and putting water in, you've actually got widespread flooding coming over the wall, coming around the wall from the ends and from the, the boat ramp area. And the low area to the north will be coming up behind the wall as well.

And that's a, there's a lot bigger volume of water involved and it's can potentially go a bit deeper or could usually go a lot deeper rainfall and the catchment can contribute to that as well. So this is a, this is a much harder type of flooding to mitigate because of the, because of the volume involved. This is to have a quick look at the, the topography of the site, the, the land levels.

And we've got some colour contours here and we've also got some colour gradients. That go from 2 metres HD up to 2.5 metres. So really I've, I've honed those colours in on a really, really narrow band of hearts because you know, at the, the crest of the seawall is about 2.5 metres and that's lowest point. So all of this coloured area that you can see on this map is below the crest of the seawall. And what you can see is that, you know, the northern end of the caravan park is below is is lower, particularly along the road and particularly at the North End up near the gate. That's where the flooding occurs.

But what you also see is the paddock behind is quite a bit lower and on the northern side of Jetty Lane, it's lower up there as well. The other thing that we'll point out on this, on this figure here is we've got some the coastal protection structures, some of them anyway the pink one line shown along here that comes from up near the boat ramp down through the top few 100 metres of the park is a masonry seawall that's, you know, blocks of rocks glued together with concrete and that's a DEECA asset.

And then we have from this point onwards going South, a number of other sea walls, which are some of them are, they're typically timber, some of them are masonry. I think there's a one or two, one rock revetment. But there's, there's a bit of a mixture of, of materials and ages. Ownership perhaps is less clear with those. Some of them might be built by the people, you know, with some of the cabin owners, I'm not entirely sure.

And all of these sea walls are in a poor to, to very poor condition. As Tracy said, we started this project when we inspected these sea walls and consider them for an upgrade. And the certainly they they do need an upgrade.

But before, in accordance with, with the policy, before we can upgrade them, we do need to consider, are they still, you know, are they still made at all or, you know, would upgrading and risk is going down to maladapt maladaptation pathway where we're locking in some some high risks. So is it a good use of of money to upgrade these seawalls? And that's kind of a bit of a crux of the question that we've been focusing on. Let's see.

And also I should say here, no move on couple of cross sections, just illustrating the same point through the site up near the the gate and one of where we can see the height of the seawall and grey at about 2 1/2. There's a little bit of a levy here or a a raised earth area just in just north of the Rotunda, low area around the road and then low area in the paddock.

And then this cross section here which goes through sites 5 and 6. That is we understand the lowest point on the seawall and we're overtopping tends to start. It's around 2 1/2 metres again low area around the road and lower area and lower again back in the paddock.

So the minor flooding, which is the flooding that yeah, occurs with a bit of when you get a with a quite a high amount of overtopping from the seawall and waves breaking over and flying in. This is the area that that could potentially be flooded can be less than this. This is sort of the hazard area for that type of flooding and that's up to about the 2.4 metre contour. If you go, the minor flooding won't tend to go much higher than this because if it gets any higher, it starts to spill over into the paddock behind. And because the volume of water in this type of flooding is relatively limited by the amount of water the waves push over then it it won't tend to fill up any higher than what we're saying seeing there.

It's affecting the road, but generally speaking, the office from the Rotunda, the gate, you know, the most of the structures are a little bit higher and it's probably not too, you know, certainly not too catastrophic this type of flooding. But if we even go up to it, like I've just raised the contour here like .2 of a metre. So not very much.

But as you can see suddenly now with the major flooding, the potential flooded area is is is suddenly enormous. The volume of water involved is huge. It's probably like flowing over the seawall as well as coming in from the north from, you know, up around the boat ramp or even further north. So this would be, and this would be flooding a lot of the old Tobin yellow swamp area going all the way up past, you know, towards colder made.

And this is quite a plausible event currently. It's, it's, it's, it's reasonably rare, maybe one every 10 years, but it'll get more frequent in future. So that's your major flooding event. And it can get deeper than that too.

Yes, sorry, can you hear it? Sarah?

[Speaker: Sarah Hendriks]

I'm just getting a question in the chat. Are you able to put this in presentation mode perhaps? So then it's just that little bit bigger because people are struggling to see it. That looks way better. Thank you.

[Speaker: Christian Taylor]

Hopefully that. Sorry, I didn't realise it was, it was small.

[Speaker: Sarah Hendriks]

No, no, all good. Thank you.

[Speaker: Christian Taylor]

Yep, that's all right. OK.

But we've done some modelling, which I won't go into the, the, the technical details of it, but we've done some modelling of the overtopping mechanisms, concluding all the processes we talked about before storm tide levels.

So taking water levels from Bass Strait, adding in the, the effect of the tide propagation up into Western Port, adding in the effect of the wind lying across the water, adding in the effect of the waves hitting the wall and pushing water over the top. And we've got a whole, you know, I think we modelled 15 years and on this right on the right-hand side, all these blue dots are overtopping events that occurred in the 15 years. And we've got a lot of very small ones. If you're below this green line, then it's nuisance flooding wouldn't bother you. If you below the yellow line, it's the minor flooding. And if you're up around or sorry, above this red line, it's more the major flooding. And then you can see it's only 2 events, impacts of sea level rise.

So sea level rise will increase the you know, the still water levels that's without the waves and the overtopping. And this, this this curve shows the occurrence of water levels like say over over a year at the site and their probability of occurrence. So the highest it gets, the top of these tips of these curve is the highest it gets. And these horizontal lines are different levels. So the red one represents the wall crest.

Currently in 2024, the highest water level without the effective waves is just below the wall crest. So we haven't got flooding over the that that we haven't got that still water level over the wall yet. But what we see is that by 2060 we certainly will have that occurring and 2100 it's going to occur pretty frequently though. You know, the highest water level is almost .7 of a metre over the top of the wall. So you can imagine what that might be like.

So I've tried to bring together all the frequency. So what's happening here is the frequency of flooding increases over time. It's not. So not worried so much about the area and the extents because they don't actually change as much. It's, it's how frequently it happens, the changes. So I'll talk through some of the key points out of this sort of fairly busy table.

So I think that we've got a number of years along the top. We've got 2024, which is now 2030 2040 2060 and 2100 and we've got a sea level rise increment. So relative to now, how much higher will sea level rise be at these times? And in 20-30, maybe 5 centimetres, in 2100, 80 centimetres or 0.8 of a metre. And the way things are tracking, that's probably a conservative estimate. It could be higher and faster than we've shown here.

But this is the standard sort of assumptions for planning the frequency of minor flooding. We'll talk about that one. So that's currently happening 6 times per year. 2030, we think it'd be around 8 times per year and then it increases up to 2100 where well, you know, it's every it's, it's, it's basically once a week. It's probably going to happen on every high tide during spring tides. I guess by 2040, eleven times a year.

That's, you know, that's, that's kind of happening once a month on the spring tides. The frequency of the major flooding is probably even more important. So we think that's about every 10 years at the moment, but that's going to increase to around once every four years by 20-30, once every two years by 2040, and then sometime around 20. And by 2060, we're sort of predicting 4 times, you know, between one and four times a year. So somewhere in this range, this 2040-2060 range, it's going to start to become something that happens a couple of times a year.

And by 2100, it's happening very, very frequently. So, and of course, when the tide is low in between these events, it'll still be dry. It won't be the fact, you know, the, the water will only will typically be even in 2060, the water will be staying up for a couple of hours. Not it's not sort of flooding that lasts for days or anything. It's it goes down with the, the tide is still a very important factor in the water level.

So as the tide goes down, the flooding will go down too, but it's just the frequency that that occurs will will be increasing. I'm going to say just a little bit about coastal erosion.

It's all, it's different hazards. It's also happening in the areas that are unprotected by sea walls. We've got a, a sort of a low earth scarp is what we call that, that little cliff and that's eroding at around. We averaged it out at around 12 centimetres a year and that that would probably get faster over time with sea level rise.

But based on current rates, we'd expect about two more metres of erosion by 2040 or 4 metres by 2060. And as the rates may be higher, even where we have sea walls, the erosion is still occurring.

The water is the high tide water penetrates through the seawall and washes out the, you know, takes fine material out of the bank and which then which you then goes back out through the seawall underneath the seawall exposing, you know, rubble and rock and things that's in the soil. And that's happening in many places.

We're not quite as fast as the unprotected banks, but it's certainly occurring as well. And it's undermined a number of the boat sheds and certainly the the concrete annexes as well. And we call these features sinkholes. There are whether you get a feature like that, that's a sure sign that there's erosion occurring through and under the wall.

So that's what we mapped that erosion hazard lines out to 2100. You can see where they sit and they take out most of the 1st row of, of sites and buildings along there.

OK, so now we move on to the, so I've described, I've been describing the problem. Now we move on to what are we going to do about it, the adaptation part. And there's, there's, there's, there's a framework for that with the, the Victoria's resilient coast. There's some policy guidance from the Victorian Marine Coastal Policy and I've got some explanation here of of some terms that I'm going to use.

So I'll talk through the key points. So if you're having to read this very wordy slide, but the the marine and coastal policy sets out a a hierarchy for adaptation actions for things you can and and the order you should consider these things in. So we look at doing the ones higher on the list 1st and if we can't, if nothing, if that won't work, we we we can move to the ones lower on the list.

So the hierarchy starts with non-intervention. The best possible thing is to do if we can do nothing and that allows the natural processes to take place.

The second is to avoid, you know, avoid locating assets and and uses in the hazard areas. So avoid exposing, exposing things to coastal hazard risk. Often that's difficult when you've already got a problem such as we have here.

The third is a nature based, nature-based methods. And what that means really is restoring coastal ecosystems that offer some protection from coastal hazards. And a classic example of that would be a wide mangrove forest or a big sand dune. And sometimes these things have been removed by, you know, development and, and there's an option to put them back.

And we'll talk a bit more about that in the context of this site in a second #4 is to accommodate. And that's really to sort of change what you're, you know, change the nature of what you're doing so that you can live with the coastal hazards, in this case the inundation and the erosion. And a classic example of that might be to put something on piles so the erosion can happen underneath it and it doesn't matter.

The next one is retreat, which is, I mean, it's pretty self-explanatory. That is move things away from the coast, existing asset structures and issues all relocated further along.

And the final one on this list, number six is protect. And protect is where you put in place physical barriers, you know, engineered structures such as sea walls or levees or to to protect your assets and uses from the coastal hazards. It's an often as last resort. It's often quite expensive, the benefits tend to be localised and it often transfers a problem to nearby areas or increases the level of risk in the future. We'll also explore this one a bit further.

So just a little bit of terminology to make the next bits of hopefully be easy to understand. We'll talk about adaptation actions. They're individual actions, things you could do and that might be repair a sea wall or might be, you know, move a building that's a, or it could be implemented planning control. So that's an individual action you could take is adaptation options. These are normally a group of actions that are coordinated together and to, you know, so strategically it doesn't make sense to do one thing unless you also do another.

So you group them together and you say that, OK, that's one option. And alternatively, we have another option which will have its own set of adaptation actions within it, adaptation options. And then finally, we'll talk about adaptation pathways.

And that is where you take a series of actions or a series of options and you implement them one at a implement them one after another over time. We do this option for a while, then we might have to change to that option. So that pathway has that time element in it, which is very important with adaptation because the level of risk is changing over time as sea level rises. And so the appropriate response can change over time as well, right?

So here's some high level adaptation review of adaptation actions. There’s a couple of lot of things, a couple of lot of things here, which we've, I can describe in a bit more detail because they've been shortlisted. There's a few things that we didn't, we sort of thought out about briefly, but didn't proceed any further with things like putting structures on piles.

You know it's not going to work. Access to buildings as lost can't campsites are unusable. And the other one that is probably worth just mentioning why we can go further with it here, is levees or docks. That's where you build an urban wall around an area to keep the wall out.

Famously, there's a lot of that in New Orleans and low lying places like that. In fact, well along the farmland to the north of the caravan park, there's a number of levees along there which prevent water high tides in and out in the fields.

Most few of them are breached by erosion. But there there is this use of levees and dikes up there. They’re really not feasible at this site, mainly because they they take up a lot of room which we don't have. They're very expensive to construct and maintain. They cut off your views and interfere with access to the beach. And they also having people living behind levees is actually a very dangerous situation because eventually the levee will be overtopped or damaged.

And if it's not, and that can lead to a, rather than just your minor flooding that's of inconvenience, you suddenly under a lot of water and there's no way out. So that's a, you know, the levees are a very difficult thing to implement safely.

But I'll talk now about some of the things that that that could work avoiding further development in the hazard exposed area. It's a bit of a no brainer. We're not going to put anything new in an area that's subject to coastal hazards.

This this is a sort of a we had to think about what could you do around the nature based type of approach and if, you know, and if you could meet, if you could take out the waves, then that would reduce the overtopping and at least temporarily for the next sort of 20 or 30 years, it would reduce the flooding by reducing the wave climb.

And you could do that with a mangrove forest. Now we know that mangroves don't naturally grow up Lang Lang. And the reason is again, the waves, it's too much wage of energy for them to establish on that shore. So, but people have done that, done this in similar places. There's a photo on the top there from a spot in the US you need to put in an enormous rock breakwater to to basically reduce the wave height as well.

So it's a bit of a while we put in the breakwater anyway. It's very expensive. And also from a beach amenity point of view, I think that this is not really maintaining what people love about the Lang Lang foreshore. So this is not one that we think's a good option. And it's very expensive as well.

Once the tie, once we get to the point where the sea level rise has pushed the still water level without wires over the top of the wall, the you know that major flooding will occur regardless. It won't even mitigate against that. So not a lot to recommend this option.

Raising the road is a possibility to to improve access during floods. It's just one measure. Raising floor levels and filling of low areas also possible. Like it's it, but, you know, quite expensive and, you know, not something that's likely to be funded by government as the buildings aren't really, you know, again, not wanting to invest in new, new infrastructure in hazard zones.

Another measure is, you know, taking the directing more of the water into the paddock and creating a kind of a drainage area in there. It involved purchase of land and it would be effective at reducing the minor flooding perhaps, but certainly not the major flooding because in the major flood events that paddock area is flooded as well. Upgrading of the seawall or revetment look, raising the crest on it would, would, would reduce the overtopping.

And there's a couple of different ways you could do that. And that would be beneficial for the next sort of 10 to 20 years.

But similar to some of the other things we've talked about, it would not prevent the major flooding where the still water level gets above the revetment height because the flooding can come in around the ends of the wall from other directions. These structures tend it's not a levy, they're not waterproof, but it would could produce reduce the nuisance and minor flooding.

And then you know, there's a risk it could lead to a bit of a loss of amenity subjective, but you know that you potentially cutting off some views and things there. And I know that this has already been partially implemented along the front with with some gabions along near the Rotunda and you know that could be extended or improved potentially potentially expensive. The seawall itself structurally needs repair and upgrade as well.

So there we've talked through a number of the of the individual actions that are available and now we're going to talk about some options. So we've grouped those into sort of a couple of of different options and we'll discuss some of the pluses and minuses of those.

So the option one and this aligns with the sort of the, I guess the bit of the do nothing approach from our hierarchy of actions, the number one first one. And so we've always got to consider this, if we did nothing, what would we be looking at?

Progressive closure really, or progressively to close and fence off damaged buildings, damaged, you know, eroding caravan sites, decommission the assets when they pose a safety hazard. And so it's progressive closure.

You know, while the while the things that are not currently undermined, they could stay, other things would be closed as they were deemed unsafe. This would mean that the caravan park might stay operational for 10 to 20 years, but I think in around that time frame, so much of it would be closed that it wouldn't really be viable anymore and there's a cost of cleanup and demolition and decommissioning associated with that.

Option 2, which we've called the minor short-term protection works, this one involves this one focuses on the next sort of 20 years and involves repair of the existing masonry seawall and raising the yeah and potentially raising the crest a little bit to reduce overtopping.

And that will provide protection for the, you know, the site facilities such as the, the toilet blocks, the Rotunda officers and cabins up at the northern end of the park for a period.
But in other areas further South, basically the the same applies with with, with the, the protections not upgraded and this sort of progressive closure going on.

Even the cost of just the repair to just the, the masonry sea wall is 1 to 3 million.So that's a challenge is to get the funds for that.

All right, protect. OK, so I've actually got another slide on each of these, which maybe I should go to to talk in more detail.

But the other ones are some major works and staged retreat. So progressive closure this is yeah, this is the the base case. So the flooding becomes more frequent.

Minor flooding you expect to happen monthly by 2040, and major flooding every you know would occur every couple of years by 2040 as well, and potentially would be occurring several times a year by 2060.

Seawall failures recur, undermining damage to structures, private and public loss of caravan sites and beach accesses possible possible the next 10 years, continuing erosion at the shoreline. So yeah, the the way this progress would be fencing of the unsafe areas and progressive closure. So this, yeah, this is the minor short-term works.

And so we're talking about, again, we'll show the Mason receivable, which is the pink part on this map. That’s the area that would be protected somewhat. And so the things behind that wall can continue to operate to around 20-40. But erosion, but yeah, but storm water over the top of the wall, flooding over the top of the walls likely to become a problem eventually.

And South in the in, you know, into this in this option, which we're considering here.

The other coastal protection structures, the ones in blue, and they extend a little bit further South than the map shows, but all the way down to the southern end of the caravan park. They would not be upgraded. OK, so the there is a have to talk about it here.

There is a major works option we looked at which was to rebuild a full 1000 metres of seawall with a higher crest level filling parts of the park to get them above the, you know the major flooding level and modifications to the drainage.

The cost is around somewhere between 10 and $30 million, probably around the middle of that. So this one was really ruled out because it's not the, the cost is simply not really viable and it's not aligned with the marine and coastal policy. And we'd be basically turning the caravan park into a little fortified island. It wouldn't be very safe.

And you know, there'd be flooding act access to be cut off during floods in, in future. And we'd be building it. We'd be built this, this, this would be what we consider maladaptation.
It's putting us in a position where the the risks are going to be higher and higher in future, risk to assets, risk to life. So it's not a pathway we want to go down and it's it's not something that could plausibly be funded either.

Option 4, the last one I'll talk about now, the stage retreat. This is an interesting one we have. The first thing I'll say is that, you know, this is also very expensive, the 10s of millions of dollars and it's not something that DEECA would fund, but it could be an opportunity for a commercial operator who could invest in in doing this. And as you can see pretty quickly from the map, it involves purchase of private land. We haven't really spoken to the the landowner about this, so we don't know how feasible that is.

The way we came up from this was, we know, we considered the case of, well, if you, you know, if you wanted to keep a caravan park in Lang Lang and, and you want, but you want to retreat it to a safer area, how would you do it?

And the key, you know, we understand the key thing is to be next to the beach. That's why people go there. They want to be next to the beach. So that's important. We don't want to move, you know, up the hill to the highway. We, if we move to the north along the beach, that's not much good. Everything to the north is low as well. It's, it's going to be flooded as badly or it's worse than exposure to hazard is, is equivalent or worse than the current site.

So that's out. We looked at moving to the South. To the South we've got that the, the bluff, the high cliffs going towards Jam Jerrup and they're eroding and quite unstable. So moving to the South is not a good option because the, the, the small amount of public land to the South is actually eroding away. And it's, it's, it's, it's unsafe and, and it's also not, there's not great access to the beach you drop on top of that bluff.

So it's not great from an amenity point of view. The sweet spot in between those two areas is really the southern half of the park. It is currently a little bit higher and less flood affected.
Currently it is subject to erosion and it does, it does have, you know, a lot of deteriorating and coastal protection structures.

But what you could do if you were able to fund the purchase of the land in the behind the southern part is you could relocate all the stuff from the northern part to that to that southern part. And that's shown as being a second row of caravans behind and you know, 2nd row and a second, two rows of sites behind the southern half. And that gives you the sort of equivalent area you've got at the moment.

I guess now a key part of for this to work is you need to pull out all the existing structures along including cabins, boat sheds and sea walls along that section of shoreline and allow it to retreat naturally. And what that means is you'll have a free foreshore area for camping, which is unstructured because the moment there's actually no, not much space left down there and because it's allowed to retreat, that will maintain a beach there.

If we build, if we, we would have maintained a seawall there and hold the line, the beach that's there will get smaller and smaller and eventually be, you know, inundated by water, but most tides and, you know, we'll end up again with just a, a wall and water and, and also we'll end up with the seaward side being inundated.

But if we let the coast retreat naturally and we have no assets there, no other than campsites as they're eroded, we can relocate them further up the hill and progressively build new roads of, of camping sites behind the ones we've got as erosion continues.

And that can potentially continue indefinitely. And you, you maintain a, a foreshore caravan park and camping park and you maintain a beach and you can stay out of harm's way. The downside is it's enormously expensive. It's not going to be funded by DEECA. It requires purchase of, of land. And it's unclear whether the anybody wants to sell it or the owner wants to sell it.

And it does require removal of the well, all the ones in the northern half of the all the cabins in the northern half are park goes straight away. The main facilities of the park are relocated public facilities. And in the southern half, we'd be looking to remove the private cabins as well to to enable for sure use and camping and retreat.

So now we come to the so they're the options. And now we come to talk about the pathways, how this all works overtime. So talking of time, I'm probably need to we've been talking for a while, so I'll try and get this through this quickly so we can have some questions.

So what we've got is you know, we've got the options there listed one to four on the left and we've got time coming along in this is like coming along with sort of the horizontal axis. You can see some years down here now I'll, I'll stress that the time estimates of when things happen is approximate because we don't know you could get several major flood events in a row. Erosion and sea level rise are all, you know, difficult to predict accurately.

But we've tried to based on analysis, you know, make an estimate of when things might occur. We've got some solid, we've got some a bar for each option and the option, the bars show when that option could be implemented, when might it be effective.

The solid part of the bar, for instance, and at the front there's a, there's a lighter part that shows the time required to kind of prepare for it.  And at the back, often there's this part with the two white lines in it that shows an area where or a time period where this option is declining in effectiveness. It's not as effective as it used to be. And that's because of sea level rise and the coastal hazards are getting more extreme over time.

So and the circles are sort of decision points where you need to make a decision. And we're at one of those decision points now. We've got some damage to the sea walls, damage to some of the boat sheds, they're undermined and that's triggered this whole process that we're going through.

So the decision is, you know, do we fix these? That's the decision point we're at now. And you know, one of the options ahead of this is at the moment we've got we can do non-intervention and these black lines kind of show what the, the pathways, how we move, show the potential pathways, That's how we move through the options.

So, you know, we can continue with non-intervention, but sometime between 2030 2040 ish, you know, the, the, the that'll this will lead to closure of the park. And that's why this, this one sort of stops.

The other option that is available at the moment is the minor works repair and raise the masonry seawall. And that's we think going to be, you know, but that there's a bit of a hurdle for that in that we need to get the funding and that's not secured. But if if, if that could be secured, then that would have now label the park to keep functioning for we think a period, a good period of sort of say, you know, 10 to 20 years.

And but noting we've still got, you know, the southern parts of the park is still being progressively decommissioned as they become once we're out of the sea wall protection. But then at the end of that time, we'll reach another trigger point where the frequency of flooding makes the caravan park option non-viable. And we look how to think with the about what what would be the what does that look like? What is the actual trigger for that?

And that might be major flooding occurring more than once a year. So if we had to, you know, the, the clean-up costs for two major flooding events in one year would likely make the the caravan park unviable.

So that's the, I mean, the trigger that happened that, you know, there are other triggers that could occur, but that we think that's going to occur sometime in the 2035 to sort of 2045 area. And that point we'll go, well, this is no longer working, what are we going to do?

And the default would be, well, the caravan park closes and we go back to this just progressive closure and once will be total closure then because there'd be no more facilities to support the room, any remaining sort of cabins or camping activities.

Option 3 is, you know, this major works to protect everything. That's as I said, it's not viable.
We've shown it is only not effective. It'll reach a point where it becomes at the end of this, we've catastrophically not effective when the levees are breached. But there is, you know, from this point, there is the final option of going to reconfiguration and retreat of the park. So as you can see, it's not an option we're looking at now.

I've nominally given it a period of six years to as, as preparation time and, and understanding how the planning and of, of, of these and the sort of things how long that takes. That's probably could even be longer than that. So that's something that would need to be planned over many years.

And if we so that when we reach this decision point, you know, the park's still operating, then there might be an option to reconfigure it and, and, and continue with a caravan park in that location, but more of a that, that progressively retreats over time. So that is the that is the adaptation pathway.

That's sort of the conclusion of where we're at.

Page last updated: 27/12/24