Predicting Sand Movement

[Pete E]

Was recently talking about sand movement with my detecting partner....

Is there a way to look at the weather forecast and the tide, and predict whether it's going to be an erosion or dumping event?

Living between 60 and 90 minutes means we don't get to observe the effects of different weather events first hand.....

[clint]

Don't do much beach but found watching for big storms with offshore winds to move the sand out to sea seemed best. Feet of sand could be shifted overnight and easily dumped back as quickly!

[Pete E]

Don't do much beach but found watching for big storms with offshore winds to move the sand out to sea seemed best. Feet of sand could be shifted overnight and easily dumped back as quickly!

I'm in North Wales, and most of the storms seem to be on shore? I will have to pay more attention to the weather forecasts this autumn.....

[HammeredDeus]

I'm sure Fred will be along in a moment to explain how he forecasts, using dried monkey giblets or somesuch...

These folks seem to making a science out of it: https://www.subterrix.com/beachcut

[fred]

Unfortunately there are several factors involved so it takes a while to understand how individual beaches behave. There are some general rules but I reckon about ten years of daily observation should put you in with a fighting chance, although thirty or more is better.

[Easylife]

I would guess that sustained wind direction mostly controls both sand and target movement. Ideally when stripped to the bed.

[fred]

I would guess that sustained wind direction mostly controls both sand and target movement. Ideally when stripped to the bed.

It certainly helps.

Sand and shingle beaches have a natural equilibrium and are usually pretty stable under whatever the prevailing weather conditions are. Movement and cutting tends to happen when the direction and/or strength of the wind is abnormal and generates waves, Some wind directions may actually cause the beaches to buildup though.

On my beaches 3 days of easterlies is good news while northerlies blow the seal flat. However, because the coastline isn't straight and has groynes and other obstructions it's usually possible to find detectable spots whatever the weather conditions. Most of the time I start out with only a rough idea of the direction I am going (it's my age ) and then have a go anywhere that looks promising.

[Mudripper]

We had a chat with Fred about the subject today.

For the last two weeks, I’ve been watching a few videos about surfing, and they also mention how the constant movement and changing deposits of sand can affect the waves… so we aren’t the only ones thinking about it.

Now, back to the movement of sand and shingle. I think it’s a bit like the weather (hey Fred ) , it isn’t an exact science. But lots of observations over time can certainly help.

There are only a few spots where I can really tell the difference, and they’re mostly sandy beaches. Fred, on the other hand, can apparently locate the exact same pebbles after a tide!

MR

[clint]

Screenshot_20260811_201042_Google.jpg

Fred watching the changing sands with his custom "ghost" Manticore....and preparing to change them to where he likes. (Allegedly)!

[Pete E]

Screenshot_20260811_201042_Google.jpg
Fred watching the changing sands with his custom "ghost" Manticore....and preparing to change them to where he likes. (Allegedly)!

[fred]

Just a bit short of a thousand quids worth of gold today so I must be doing something right! Unfortunately somebody has posted about a ring lost recently in the same place so I rather think that my take will be much reduced.