My reckoning on it is that features on shallow beaches change every time we have a strong tidal surge or storm, which in Ireland you could say every month or so.
Features on deeper beaches would also change during storms, between the low and high water mark more so than in the gulleys. It's that one question that puzzles every beach angler.
I just pick a spot, on a rising night tide and go fishing. If I catch fish it's a bonus.
Here's the link to that helicopter view, Gkelly(thanks Gerry) put it up a while back.
I find it very helpful.
http://www.coastalhelicopterview.ie/imf ... Helicopter
it's great you can map an area as your fishing . You would be amazed how you thought an area would be on the bottom as opposed to how it shows up on the fish finder 
and I can get to all those places out of reach from shore anglers and boats are to big to get near.