[Closed] How close would you buy a house to a tidal river?

My concern is that at sometime in the future the house will become possibly uninsurable / un mortgageable and eventually become worthless.

Follow your gut instinct.

30cm from the house is way too close for comfort for me!

Check this

https://flood-warning-information.service.gov.uk/long-term-flood-risk

And you would need to ask questions about any previous insurance claims etc.

Sea levels arent going down in general.

Well I work in that particular industry.

Pick the highest tide, a flooding river and a large storm surge all at once. Or Google the North sea flood in 1953. 20 years isn't nearly enough time to indicate what might happen. If it's in Scotland Google SEPA flood maps that'll show you what you might expect.

I'd rather miss a lovely house than lose everything in it.

This 30cm from the house.... What's the difference in elevation? If it's 4m below it that's very different to being 5cm below it.

If you're really keen to get more info the Metoffice UK climate projection data UKCP18 can provide some detailed projected sea level rise data per IPCC RCP scenario per time horizon.

Where? And where in the estuary? And what sort of river feeds it?

my office is right on the river dart near the tidal limit. (and we make tide gauges..)

the river gets to within 30cm (height) of the factory on the highest of highs normally if there is a big freshwater input from the moors. 10 mins later it’s going back down again. We are right at the top of the estuary so the tide has lost a lot of its power and the fresh water input dominates. Don’t get much of a low tide on those days but that’s not really a problem.

the pub next door has barrels floating round the car park for a bit on days like that.

No I wouldn't. Flooding, climate change and flood risk management is my job. Unless there were extreme mitigating circumstances I would not buy a property at risk of flooding.

This is where me and Picton road find out we work for the same company...

30cm from the level of the house

Reads to me that that's elevation.

I would be very wary - and I would rely on what the neighbours say. It's a long term investment and 30cm isn't enough for the long term.

Nope from me - but...

...what's the floorplan of the house like? Where I live (not my house!) the river floods the houses alongside it pretty much every winter now. The houses are 3 and 4 stories though with the ground floors used basically as basements and anything decent stored in them gets moved upstairs if flooding is predicted.

It would have to be *very* cheap because "My concern is that at sometime in the future the house will become possibly uninsurable / un mortgageable and eventually become worthless"

Swim , swim away as fast as you can.

The highest tide in the last 20 years is 30cm ish elevation wise below the front door.
Its tidal enough that that i wouldnt be worrying so much about it flooding from rain water..
More the future predicted rising tidal heights and possibly re-selling the house in say even 5 years time..

My answer in response, is how high is the hill it's built on?

🙂

No chance,just look at some of the horror stories from places around the country.

and I would rely on what the neighbours say

I would take any neighbours* recommendations with a pinch of salt water

* unless they are as clued up as joshvegas and pictonroad 😉

Its literally water front. You can walk out of the front door.. walk 20 metres and you are down a slipway and onto the beach. The tidal range is massive.. its about a 6 metre range on todays spring tide.. and about 4 metres range on a neap.

I imagine if you are asking on here you already know the answer.

I'm looking for place just now and passed on one which was next to the Gala water because I'd seen it at it's highest and decided not to risk it.

I work in FCRM, I've dealt with too much flooding to even consider living near any water unless it was overlooking from atop of a big hill.

You need to also consider the Storm Surge risk. It's not just confined to the East coast.

OP
Is it this house? 😉

All the hydrologists that I know live up a hill. That speaks volumes

Its currently not at risk of flooding. Its still insurable.
It was 30cm elevation wise off the highest tidal event in the last 20 years.
Water levels are rising every year and continue to do so.
How long will it take to rise 30cm?
Its such a slow incremental increase.. but at some point sea level rises are going to become a huge issue and people will get displaced. Its just whether its worth the gamble as its such a lovely house and in an amazing position.

Nope, walk on by. I'm sure Google can throw up many examples of the scour and storm effects of water on buildings and coastal areas.

I wouldn't buy a house at less than 10mAOD given projected sea level rises, especially if you want an inheritance for your kids.

7-8 years ago I rented an estate cottage on the banks of the river Dee approx 17 miles inland. I remember asking at the the time of being shown the property whether there were any flooding issues (it was a good 3m+ above normal river level and ~30m from the bank itself) I was told no, never been any problems...

Couple years later there was was about a months rain dumped in the Cairngorms in the Dees catchment area over a single weekend and the river rose 2.5m and broke it’s banks >25m. I remember watching with my neighbour (the ghillie), the factor and the ‘laird’ as the water was rising up my neighbours garden towards his front door...

Fortunately it stopped two thirds up and we were both spared. Another 0.5m he’d have been flooded, 0.75m and I would’ve.

10 days later there was more biblical rain but fortunately (for us) it fell further north and flooded the Don valley instead.

I think these were deemed one in 500 year events (within ten days of each other!).

Both estuaries were severely flooded at the time. It was as completely mental, main roads closed, F&RS peeps in wetsuits and BA (in Kemnay!), there were even Council emergency shelters and stuff set up (my mate was in charge of coordinating them).

That was close enough for me. Climate change predictions is for rising water levels over the next 50 years.

You feelin lucky punk?

and I would rely on what the neighbours say

I would take any neighbours* recommendations with a pinch of salt water

Oops! Quite so, I meant to write "I wouldn't rely on what the neighbours say"

I’m looking for place just now and passed on one which was next to the Gala water because I’d seen it at it’s highest and decided not to risk it.

I can see Gala Water from my window.
I'm quite close horizontally but fortunately quite far away vertically.
I'm in Stow BTW, if you need any local knowledge PM me

I work in FCERM. I wouldn’t buy the house.

@cloudnine - don't fall into the trap of basing any decision on observed data or anecdotal evidence. What we've seen is absolutely not representative of what can happen.

By the end of the century, with an orderly transition to say IPCC RCP4.5, the average UK sea level rise will be ~0.5m. This is using the median of the projection data not the extreme 90th percentile view.

In simple terms even if we somehow manage to get on top of emissions,by the end of the century the sea will be 0.5m higher. However this is using the median and it's highly non-linear - it could be an awful lot worse than that and that is not even the worst case scenario.

TL;DR buy the house if you want to get wet in the future

I would look at the cost of making it flood proof to the height of say +50cm
Exactly what the entrails I dont know , some sort of barrier , waterproof doors , airbricks moving or sealed up. There will be specs , and companies who will sell you the gear.

If its only ever got to within 30cm , adding 50cm gives you 80cm which allows for waves / surges and prats in 4x4 with snorkals blasting through floods in a 1994 Disco.

My house will be gone in 30 - 40 years as the sea will overun the land imo

You might be able to build a wall around the place , with drop in slotted barriers . Have to be strong mind but thats what thye have done locally and it seems to work

One of the problems with flood mitigation measures is the aesthetic impact, a house being purchased for the views could be ruined by that.

"sometime in the future the house *will* become ... uninsurable / un mortgageable and eventually become worthless" FTFY, personally I wouldn't touch it with a barge-pole, even not knowing the details.

I too have worked in flood risk and now research sea level change. Eventually the house *will* become uninsurable and then when the high water exceeds the house level then ownership will pass to Crown Estate. In between those times, possibly some time in the next ~30-100 years, you are gambling with what is the re-sale market for something that the actual risk posed to the property is increasing all the time and the market (general public) is becoming more aware of the issue? What is the appetite to buy a lovely house for ~5 years and hope to sell on at not-too-big a loss or potentially even no loss? The problem is none of us have a crystal ball. The biggest risk financially is if the property were to flood during your ownership, then the sale value plummets and the flood risk map and insurance will update. So if the biggest risk is from a weather event (like a big storm surge + high rainfall, coincident `tidal' plus fluvial) you don't know when that big event is going to happen. Like the example above, you might have a 500-year return period event happen next week, or it might not happen for another 500 years. And sea level rise won't be a nice linear increase in time that you can keep an eye on and bet when is the right time to sell. The change that will happen on that river really depends on both the river and coastline characteristics and their management. I know of some big rivers that vary by 30 cm because of dredging or other harbour activities, and the relationship between coastal management and the fluvial and tidal flood risk can be extremely complex. You should at the least look at the Shoreline Management Plan or River Catchment Management Plan and see in the near- and mid-term is there a plan to hold the line or improve defences to keep up?

I am intrigued as to where the property is, if indeed it is a clear run to a slipway with no flood defence but also not in a flood zone (not even the 1-in-1000 return period?).

If I already owned the property, I would expect to not get affordable insurance and be considering self-insuring and renovating the ground floor so it is quickly recoverable if/when flooded. As above, looking to buy, I wouldn't.

Crown estates own up to Mean High water which is not the same as the flood level.

We got in a dispute with them when we were building our new factory. Having two tide gauges installed on site helped prove we were right...

I would also be considering if it is in a sheltered location. If not, you need to factor in wave overtopping/impact. Tidal flood risk mapping is based on a static level and is a combination of astro and storm surge to derive a level. Wave impact is on top of this. It's likely that a storm surge, which is a product of low pressure, would also be accompanied by significant waves. As already said, have a look at sea level rise predictions for the area where the house is located. Rise is mm per year per epoch and is exponential.

I work in flood risk, have worked on Coastal flood risk warning rotas and would not be buying next to the sea, unless I had the finances behind me to self insure and make the ground floor flood resilient.

Highest tide (the astronomical phenomenon, easily predictable) or highest storm surge (wind+pressure generated, may change in future) on top of a spring tide? And what about flood risk from rainfall too? That will change too dependent on both climate and upstream development and land management.

I'd be looking into it very carefully and have the background to do so...

Sea level rise due to climate change isn't the only issue here at all, but will make everything worse.

I also work in sea level research (and know Kona Girl) and also wouldn’t touch it for the reasons outlined by various people above.

Cost in getting rid of the STW approved T5 and buying a new load carrier...

I meant to bookmark the link, but someone on here posted an intresting link (sometime last year?) to projected water levels by ~2050 around the UK, loads of land to the sides of the River Itchen in Southampton and the reclaimed land alongside the dual carriageway towards Totton etc. was expected to be at major risk.

30cm above the worse flooding in recent decades... Run, Forest, run!

someone on here posted an intresting link (sometime last year?) to projected water levels by ~2050 around the UK,

It was probably this link https://coastal.climatecentral.org/map/6/-0.9537/51.4473/?theme=sea_level_rise&map_type=coastal_dem_comparison&basemap=roadmap&contiguous=true&elevation_model=best_available&forecast_year=2050&pathway=rcp45&percentile=p50&refresh=true&return_level=return_level_1&slr_model=kopp_2014

You can change the setting for various different scenarios.

These are the most up to date UK specific projections (these don’t include the worst case Kopp et al 2017 model that the climate central link does - yet - we are working on it but COVID delays!), and do include detailed vertical land motion, but it isn’t as user friendly as the climate central map. https://www.metoffice.gov.uk/research/approach/collaboration/ukcp/marine-projections

That looks familiar, thanks @ahsat !

I think a few of us on here might work for the same place

Kneebiscuit - If we are thinking of the same place, I did for 15 years but don't anymore

I wouldn’t buy a house at less than 10mAOD given projected sea level rises, especially if you want an inheritance for your kids.

This.

One of the recent BBC documentaries on coastal change / flooding had a really sad story about an ex-soldier who had sunk his savings into a property "near" the east coast. He knew it was at risk from erosion, but looked at average loss over the preceding decades and figured he had enough time to see out his time there. Anyway, two storms later and his house was falling into the sea whilst he pottered around below it with a mini digger doing his best in the face of the inevitable. The point was - past events and timescales are a poor predictor of future events when you are dealing with climate change and probabilistic events which don't follow an easily understood predictable path. It is also stressful home ownership.

Ex-Welsh Water geologist who used to work from offices on a tidal river that flooded, not easy to manage a flooding event from offices that flooded:

All of the above and I'll raise you all with a tsunami risk. "Wot, in the UK?". Yes, in the UK. When sediments slump off the continental shelf they can create impressive tsunamis. Historically huge but unlikely to be repeated:

https://en.wikipedia.org/wiki/Storegga_Slide

And more modest geological events have led to tsunamis in the UK:

https://en.wikipedia.org/wiki/List_of_tsunamis_in_Europe