Tuesday 18 December 2018

Waterblind

D'ye live in these [Western European Archipelago WEA] islands? How was Storm Deirdre for you? It was wet wet wet for us. It rained from wee-hours Saturday 15/12/18 for 24 hours. I got up at first light and, with my azada and a shovel in gloved hands, I went to clear the drain that runs up beside the lane to our house. It's important to do this in the rain because then you can see where the debris is getting accumulated and scoop it clear. I was thereafter confident that the water would run away below us. In the early afternoon it eased off a little and I peeked out of the gate to see water roaring down the drain from above. I wasn't surprised: Storm Deirdre delivered about 50mm of rain in 24 hours. Usually 24 days would have to pass to accumulate that much precipitation. 15km East of here, the River Slaney burst its banks at Enniscorthy [again] and flooded the shops along the quay.

It was no time to creep back under the duvet and hope that things would be okay. Therefore, I shucked myself into my rain gear and plodded up the hill with my tools. Sometimes a mighty back-hoe is the tool of choice - ripping and tearing and dumping stuff in and out of the way: but they make a terrible ragged mess which will be particularly vulnerable to subsequent water damage. Sometimes a more focused Little-Hans-at-the-Dyke attack is better. In 1997, after we suffered the first destruction of our access road from a surfeit of rushing water, I button-holed one of our neighbours as he drove up the lane to talk about a solution. I pointed to a heap of 2-inch-down or Clause 804 gravel in our yard and said he could have as much as he wanted to make berms across the lane above our house. We agreed 4 places where a small intervention would turn any water off the road surface and into a big drain that would take it elsewhere. The next few times he went up the mountain to view his sheep, he brought up a front-loader full of aggregate and dumped it at the appointed places; and smoothed it out with a shovel while I was driving a desk up in Dublin. Over the years, these humps have settled down and grassed over and are, for intermittent flash floods, as good as concrete.

My Deirdre task was to make sure that the exits at each of these escape chutes were not clogging up.
Berm001. The lowest berm was holding firm but the ruts of the roadway above were inches deep in running water. As the slope is about 1:10 there is a lot of kinetic energy in the moving water and pebbles were bouncing along in the torrent - the twigs and fallen leaves or spikes of gorse Ulex had already been swept clean and down. My problem here is that, three years ago, we installed a long 30cm ⌀ plastic drain-pipe to carry the spill-water downhill. The plastic pipe is super slick inside but it's a long flattish journey for all the debris and I am concerned that it is slowly filling up. When it rains enough to flush things through, more crud is coming down from above. I only put in the pipe to stop my neighbour-above from swinging his tractor and trailer into the open drain every frigging time he turned into his field. The collapsed drain was invisible to him but I'd go up periodically to shovel the debris clear against the next flood.
Berm002I went up to barrier two knowing in was a lost cause. A while back, the same neighbour had decided that there was no advantage to him in allowing water to spill into his field 3 or 4 times a year . . . as insurance that there would be a lane to drive up to that field in the future. This is ironic because the 1997 flood stripped the topsoil and a generous dressing of artificial fertiliser from his newly created pasture and dumped it all in a heap on the county road. That Spring he'd been clearing and smoothing that 4 hectare field having knocked and buried and levelled all the walls and drains and ditches that had separated the 5 smaller fields which he'd bought at auction. After the storm and the loss and destruction he confessed ruefully: "The village idiot stood on the ditch and called out 'Sean, Sean, where's the water going to go, Sean?'" He had to get the back-hoe back on site to restore the drains that kept the mountain catchment delivering itself into the top of his 4 ha field and leaving 5 minutes later from the bottom corner.
Berm003. Like Berm001 this was holding its own and performing at specification. But like Berm001, there was a lot of water being turned aside here. With some trepidation, therefore, I quickened my pace to find out why so much water was travelling.
Berm004. Aha! When I arrived, water was brimming behind this dam and spilling over into the road-bed to gather speed on its way down hill. I started shovelling sods and mud up on top of the berm but these were getting carried away as soon as they were thrown up. I was alone, increasingly wet & out of my depth in water and resources. So I stopped and looked at the situation sideways; in particular at the place where the lake behind the berm headed East and into a capacious drainage channel. Water wasn't making its exit. I plunged into the lake and started to pull crud from the holes in the wall through which the water was meant to drain. Out came twigs, leaves, brambles, gorse, matted grass, old bracken: with each clot, mud and small stones came out with cloooargh sound. It was like a bath draining: the outflow increased dramatically and the level of the lake fell 20cm in about five minutes making the remains of my pathetic earlier shovellings look like sprinkles on a cake.
This is The Mountain Gate aka The Iron Gate; just to show what blurfed out of the drain this last weekend. The largest stones are as big as a baby's head. Also note the ominous sign on the gate. Forestry Operations are 15 hectares of scrubby hillside which is even as I write being grubbed up and stripped of bushes and ditches to plant Sitka spruce Picea sitchensis. The rain isn't going to stop because they planted some trees and a lot of exposed top-soil is going to start travelling until the tree-roots spread out and start holding things together. Tricking about with running water can be fun but only if you box clever. Being water blind [Fr. aveugleau ?] or staying on the sofa watching telly when it is hosing down outside is just laying yourself open to more expense and trouble later on.

No comments:

Post a Comment