Wednesday 25 October 2017

Rain, pave, wash away, leaves have gone and blocked the drain

It can't have escaped your notice that we've had some pretty bad weather recently with the fallout of two storms, bringing heavy wind and prolonged rainfall and all this water has to go somewhere. In the face of an ever increasing drive to build new houses and a growing trend to pave over front gardens for extra car space (and less maintenance) less water is soaking into the ground and is taken away through drains. These drains enter into man-made channels:


Where these channels end, the water enters old streams and they simply can't cope with the increased volumes of water often resulting in large erosion issues. This is one of the reasons why we have put so much effort into protecting stream banks with our wooden bundles made from harvested willow from the LNR. These fill up with silt and work brilliantly.
These bundles were done several years ago and saved a huge erosion point from getting worse.
A big problem starts to happen with massive downpours, which is compounded by the heavy winds breaking off lager branches all accelerating natural autumnal leaf fall. Larger branches and twigs get washed and trapped against the metal grills of man made culverts, which make a kind of nest which gets lined with all the leaves, which cloggs up the flow of water. When this happens, the water levels back up , rise and even greater erosion and flooding occurs.
This was back in November 2014
Luckily, there is a department within Torfaen Council who have responsibility for drainage. However, it isn't just culverts they look after, it is also all the drains on all the roads in the county. It doesn't take too many autumnal leaves to block these drains, resulting in localised flooding. It is impossible for these teams to be everywhere all of the time and in fact a dog walker told me this evening that they were out cleaning the culverts on the LNR only last week. To help out and from time to time, we get out our muck rakes as volunteers and help to clear out the culverts which pass through Henllys LNR. Today was one of those days, in the pouring rain.
Before
After
Before
After
At the minute, the whole LNR is saturated and the ponds are full. There is surface water everywhere and the streams are all raging. The desire lines are all marshy (apart from on our Gwent High Sheriff's Community Fund path) and the water is just finding its own way down to the lowest point. I came across this really interesting rutted stream where the water just flows its way down off the main meadow and then disappears down a hole. This looks cool, but I don't know if it is washing the bank away creating a potential hazard. Only time will tell. This little stream only came about as a result of LNR users walking along a desire line on the main meadow and the water will always take the easiest route.

As a final word of caution, if you are visiting the LNR, bring your wellies (and a buoyancy aid).

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