Laggan Reservoir
I was away on a tender visit today. I always think this is a nice spot when the tide is high on Laggan Reservoir so I stopped here on the way home. It is close to the starting off point when we walk to Lochan na h-Earba.
It was surprisingly awkward to get to this position, involving a scramble down a "rip rap" revetment then splodging over, and braking through, big plates of thick ice left high and dry upon the water receding over the last day or so.
Just realised I better explain what "rip rap" is. Any coastal, river or reservoir bank may be subject to scouring and erosion by wave action. The bigger a lump of rock is, the lower its specific surface area is with regard to mass. Hence if you drop a grain of sand in to a stream it instantly washes away but if you drop a 9 ton boulder in to the same situation it will sink to the bottom and remain static despite being of the same material and density as the grain of sand. Reservoir banks are often protected by large interlocking boulders. Ideally they should be angular blocks of rock (usually oversize debris from a quarry face blast) so that they key in to together. The formation and stablity of rock armour (rip rap) slopes is the result of skillfull work by digger driver and his banksman. It has proven to be a sound engineering solution but mother nature always wins in the end.
Comments
Sign in or get an account to comment.