Wednesday, 5 December 2012


To Cishan and back via the 182 running through Longci district this morning. I left Tainan at 5.40am and arrived in Cishan at just before 7.40am. That's me above in my new cycling gear (basically, a helmet, a pair of gloves, a pair of lycra shorts and some plastic specs) at 7.18am this morning about one third of the way along the 182 after the little village of "North-flower". Some brief conclusions on the ride:

1) That 182 through Longci is the toughest ride I've yet managed on the bicycle; several steep and long drops. The return journey to Tainan is much tougher than going to Cishan because there are two steep climbs in particular that go on for several kilometers each (amusingly, the sign for the last one tells you the climb is for only 1 kilometer - but it appears after you're already halfway up it).

2) My little 26-inch wheel, flat-bar bike is a bit too small for me; even with my newly adjusted saddle position I still found my knee moving forward over my toes whenever I ended up leaning forward for a bit more push. I had two solutions to that; the first was to try to keep my arse as far back on the saddle as possible and my heels as far forward on the peddles as possible; the second was to peddle from a standing position. I don't think there's anything else I can do about this but it wasn't unmanageable.

3) I have finally run out of excuses for not getting with the times and buying a new phone; my four-year old swing-clip Nokia finally snapped after being crushed by the weight of the DSLR in my backpack. The obvious choice would be to get a 3G smartphone, but as with the Nokia, it's likely to go through a battering being dropped on the floor a lot when I'm trying to get the dogs on the lead and such. I can't put the decision off much longer though, because I'm phoneless until I sort that out.

4) My old outdoors jacket which I bought in Kenting five or six years ago needs to be replaced; the lining is starting to come to pieces and it wasn't keeping the rain out anymore - my sweater and T-shirt were soaked through.

5) I miss my old ipod shuffle; I don't know where it's gone or even if it still works but it would have been very useful this morning as what I needed to be listening to was something like this, but instead, like Joe Simpson and that "Boney M" song, I ended up with a Billy Ocean track. For f*ck's sake.

Anyway, after having called one of the engineers at the WRA in Kaohsiung yesterday, I finally got hold of a bmp file (resolution is poor) showing the plan of the diversion; my mistake was in trusting my altitude numbers and thus disregarding all possibilities along the canal south of the 80m mark (approximately just to the north of the prison complex). I was looking along the northern section of the canal, when in fact the exit point is as far south as possible (which according to my altitude calculator is 72m, or 5m lower than the 77m of the Neimen control gate) and runs under the new Taishan military camp - to which public access is of course denied. I should have guessed. It's a simple matter of engineering efficiency; make use of existing infrastructure as far as possible and keep construction of new infrastructure to a minimum. That new infrastructure, aside from the obvious tunnel through the mountainside, also includes what I had originally taken to be a footbridge crossing the stream toward the mountain at the back of the military camp; this has to be an aqueduct channeling the water into the mountainside.

The angle to the Neimen control gate matches up almost perfectly (though whether the tunnel itself runs in a straight line or not is another question)...

Below is a google earth shot of the whole section where the channel for Agongdian reservoir diverges from the irrigation canal. The diversion channel is the broader body of water at the top and the irrigation canal is the narrower body of water beneath...

The irrigation canal originally enters straight into what becomes the diversion channel, but some of the water is redirected at a 90 degree angle by a small weir and control gate. This water passes through a tunnel slanted at an angle of 45 degrees or less into the lower channel which then continues on southward to provide irrigation water for the remaining farms in the Cishan district. Below is the original irrigation canal as it enters the channel with the control gate to the right...

The difference in height between the two channels looks to be no more than two meters or so. This next image shows the water passing out of the tunnel from the control gate above into the lower irrigation channel...

The actual diversion channel transitions into a deep groove before entering the narrow tunnel...

Looking at the entrance to the tunnel, it is obvious that this is old architecture that pre-dates the plan for a diversion channel to Agongdian reservoir. One possibility is that this was originally a two-pronged irrigation channel, with one channel (this one) running a little further to the west (closer to the mountains) and the other channel running a little further to the east (closer to the river). Another possibility is that this channel allowed water to enter a now lost treatment plant prior to being pumped out for residential use. Here is what the entrance looks like...

It is complemented on the left by a gated antechamber which leads directly into a large culvert perhaps two meters in diameter which I suspect is a kind of spillway. The following google earth shot appears to confirm that since it shows an opening into the stream to the left allowing water to pass out into it from a subterranean source...

The main channel itself must run underneath the Taishan military camp and proceed across the stream via an aqueduct (I can probably photo that too if I'm clever about it) into the mountainside. So what I suspect has happened is that the recent purchase of land in this area by the military for the construction of the Taishan camp also allowed this two-pronged irrigation canal to be adapted to serve the diversion of water into Agongdian reservoir. The only new construction would presumably be (a) a channel running underneath the camp, or some means of covering it; (b) the aqueduct, and (c) the tunnel running through the mountainside for just over a mile (1.67km) to deliver the water to the Neimen control gate.

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