Tuesday, 3 April 2012

Scout's Hour

I took my dog on a quick trip out to Nanhua reservoir yesterday afternoon - an hour to get there, an hour to get back, and an hour while I was there to check things out.

The water level at Nanhua reservoir is quite low at the moment; when it's full that bridge will be completely submerged. And no boats either.

Dead snake - looks like it had been flattened by a truck, the poor thing. I was going to make a return trip today to get some better shots of the second chute exit and have a look around the north-east end, but a woman from the government had to interfere by making herself an "appointment" with me at extremely short notice (less than an hour!) and without my prior consent or knowledge (and the last time she made one of these "appointments", she failed to turn up, didn't call and didn't even answer her phone).


  1. Mike, I must assume that your interest in resevoirs is an academic interest/field of study. Or is there a degree program strictly for resevoirs?

  2. John... yes my interest is academic, but not in any formal sense. I wouldn't step foot in a university again, unless it were to chat up the best of the post-grad foreign girls maybe.

    An interesting engineering problem with some of these reservoirs - the "trough" reservoirs set high up in the mountains - is that they tend to suffer from over-sedimentation during and after periods of heavy rainfall (e.g. from typhoons). This reduces the amount of water they can hold and necessitates a lot of expensive, annual dredging. A couple of years ago after a very serious typhoon in 2009, the water office people initiated a program of tributary widening and weir-construction at two of the bigger reservoirs here in the south, so as to dissipate the energy and therefore also the sediment carried by the tributary waters.

  3. Mike, has incorporation of river sand traps been considered? They've been utilized with some effectiveness on streams and rivers here in Michigan, and could be incorporated on the resevoir feeders.

  4. John, I'll have to check - I'd imagine that these pools and embankments and perhaps some other type of filtering system (e.g. straw bales behind the weirs) might help, but the main thing is to slow down the speed of the tributary during heavy rainfall. The water office chaps must have had to do a lot of guesswork because prior to 2009 there very few weirs on the tributaries and therefore no water-guages to measure rate of flow during stormwater periods.


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