Flash Flood

There was tragic news earlier in the week about 9 people killed by a flash flood in Arizona.  They were enjoying a sunny day at a popular swimming hole unaware of the torrential downpour miles upstream.  Apparently the first anyone knew of the changing conditions was a rumble like thunder and then a wall of water came down the river and was on them in seconds.  As is clear from the video in the above link it is not only the water but the debris in the water that causes such tragedies.

People say the River Dart is a ‘flashy’ river though it is not immediately obvious how that can be.  Yes there are relatively big flood waters but normally from looking at data on the Environment Agency River Level Monitoring Site it looks like the levels rise and fall relatively slowly.

Wild Swimming
Wild Swimming

Flash floods do happen here: Lynton and Lynmouth in 1952, Boscastle 2004, Coverack last week, but are thankfully uncommon.

As far as the Dart goes yesterday brought what was a borderline flash flood as recorded on the above Env. Agency website.

Wild Swimming Still Pool
Wild Swimming Still Pool

On Thursday evening I swam my usual twice up and down the 300m pool near Dartington.  The river chattered over the stones and was still perhaps an inch or so higher than the typical summer low after Tuesday’s showers and just touched the last of the steps near the swing which hangs 6 feet clear of the placid, clear water of the main pool.  I swam with a girl who had stopped off on her run, 2 boys were messing about with snorkels in the shallows by the sandy beach and the 2 girls were taking turns on the swing.

The forecast was for rain.

When it came it was torrential hammering deafeningly on the tin roof at work.  I had to go and take a look at the river.

Beneath the bridge the shallows and banks of pebbles where the heron had been stalking yesterday had vanished.  However, the water might be just an inch deep, a covering and with no marker there was no knowing.

At the pool though it is obvious the level is up about 4 feet if not more.  Tree branches drag the surface and the steps have gone along with the little step from which I dive and the concrete ledge is being washed over.

Stepping into the water at the edge of the beach it is waist deep where yesterday there were dry stones and I wade out to the trees where dark brown water slooshes around the willows.  The water here is however barely flowing, dammed into a little pool by trees and bank.  Walking back along the bank it is clear that in just a few minutes the level has risen to fill the hollow under the leaning tree trunk and back at the steps the ledge has gone.

The water in the enclosed corner stirs gently, there is less flow than in the mainstream on a normal day and I bob easily in the surprisingly warm water keeping place with just gentle flicks of my hands and feet but with nowhere to go there is no point in staying in longer than to take a few pictures and watch the world quite literally pass by.

Hauling myself out using the small tree it is clear the water is rising fast.  It has now breeched the last of the rock and the oak tree roots are awash leaving just a few inches of the tallest rock poking above the surface and even that get swamped once in a while.  As I dry off I see a tennis ball whisk by and several plastic bottles and a surprising amount of potential firewood.  A long heavy length hitches on some trailing tree branches hauling them down until the log is released and the branches spring back with a crash.  The log broadsides the next branches and sticks creating a dam and a noisy gurgle of water.

The last of the rock is finally covered and at the same moment the water catches the tail of rope at the swing and sets it dodging and rocking, the water pulls one end in, flips it up and the other end is dragged in.  That is a rise of 18 inches in 30 minutes.

What looks like a honeydew melon in terms of colour and size spins past.

I’d like to stay and watch (as it turns out the level will not peak for another hour and the monitoring station upstream shows another 10 inch rise yet to come) but instead I’ll come back in a day or too and look for the tide line of debris on the all but submerged fence beyond the vanished beach on the far bank.

More heavy rain is however forecast.

 

 

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