Another Piece Of The Puzzle: A Second Control Gate For The Cishan Diversion Tunnel

Now that the autumn has set in, so have the mosquitos. My bare feet were bitten in the early hours last night and so, just before 6am, I got up to go buy some camphor ointment from the store and on the way back home decided to stay up, get ready and jump on the big bike to drive down to the back of Agongdian reservoir again. I had studied the maps carefully earlier in the week and had made mental notes of which farmers' roads were the more likely candidates; even though nothing of the diversion channel appears on any maps, I was beginning to piece together an inferential route based on knowledge of the channel's entry point into the reservoir and the topography to the east of that point.

The first road I had marked (3rd right from my exit onto the main road) turned out to be a tantalizing disappointment; although the road fizzled out into impenetrable bush on the top of a hillside, I could hear the clear sound of rushing water in the valley below. Since that location on google maps lacked any stream or watercourse, I knew that it was the diversion channel I was listening to - but it was hidden from view with no way to get down into the valley.

The second road I had marked out for exploration (4th left from my exit), further to the south and east off the main road, turned out to be a dead end with just a few pools nestled between the mudstone ridges; no flowing watercourse at all. However, returning the way I had came after picking up something to drink, I took up the 5th right from my initial exit point after noticing that it was lined on one side with the tell-tale white cinder-blocks indicative of an access road used by the Water Bureau. Somehow this had escaped me previously. Sure enough, at the end of that little concrete road I found just what I was looking for...

Those two buildings house hydraulic control gates for the diversion channel, which must be running underground for some distance prior to this point. However, the way was barred by a gate topped with barbed-wire extending around both sides for some distance...

The sight of two buildings piqued my curiosity; why should two control gates be necessary when there is only one diversion channel? Perhaps there is a second channel, or adjacent underground stream? Or is the second gate to provide an additional outlet for flood control in case, by some freak accident, the primary channel ended up carrying too much water into the subsequent stream bed? The other thing that was interesting was that there was no visible outflowing channel in the area immediately in front of the two buildings, which made me suspect that after the two control gates, the channel was still underground and exited into the natural watercourse some distance ahead. The following image from google earth confirms that conjecture...

Since I was blocked from entering, I sat down to think about what to do and that's when I noticed, through the trees to the north side of the road, that there was a large white house on top of the overlooking hill. I knew that must be at the end of the next farmers' road (the 4th right from my initial exit) so I thought I'd drive up there and ask the owners if they minded me taking some pictures of the channel from their garden. However, when I drove up there I found that it wasn't quite what I thought...

The house had been abandoned many years ago and was now a mere shell. As I approached the lower staircase, I stopped: there was a large web barring my way with a type of spider I'd never seen before. She was very similar in size and shape to the golden orb weavers, but her colour was black and red instead of black and yellow...

I don't know whether this is a different species of orb weaver, or whether this one is male instead of female (or some sort of mutant). Compare with a regular golden orb weaver...

After I carefully lifted my legs as high as possible to avoid damaging her web, I made my way up two flights of stairs to the third floor, hopped over a wall to stand on the roof of the adjacent building to get a better view. My jeans ended up covered in brown flecks of some sort as nature had long since began its' process of conquering the house...

From that vantage point I was able to look down into the valley to see the white cinder-block lined access road to the left, and a large weir blocking what seems to be a natural watercourse to the right. Unfortunately, at 10am the sun was directly in front of me...

In the middle of the image, as if placed there on purpose, a bunch of bamboo trees hid the two control gate buildings from my sight, and there was no way I could shift further to my right to get an angle without falling off the end of the building. This would be an ideal place from which to launch a lightweight camera hung from a helium balloon, so long as I could prevent the rope from getting tangled up in nearby tree branches.

Below is a shot of the weir blocking the natural watercourse to the left; to the right of that weir the watercourse continues north-westward and I suspect (as per the google earth shot included above), the underground channel empties out into that watercourse at a 90 degree angle, although the little bit of green water that is visible in this shot does not show any waves, as would be expected from another source of water emptying into it. I wonder why all the trees sprouting from what must be the "roof" of the underground channel have been cut, yet not felled completely - they appear to have been "half-cut"...

Climbing back down from the house, and carefully avoiding the spider-web, I was putting my things away to follow the adjacent road down from the hilltop into the valley, when I caught sight of something moving in the undergrowth at the edge of the road. It was a snake. I only saw it long enough to take account of its length (perhaps just shy of a meter) and colour (brown with some kind of black patterns on its back - possibly diamond shaped) before it disappeared over the curb lip and back down into the valley. I scrambled uselessly to readjust my camera settings, but it was gone in a flash. That is the second snake I have seen in this area (Yanchao and Tianliao) during the last two weeks - I briefly saw one earlier crossing a mountain road in Tianliao, but it was too far in front of me and gone by the time I started searching for it.

Heading down the adjacent road into the valley, I hoped to find the channel and possibly even some sort of path to take me back up toward the weir blocking the natural watercourse. At the end of the road there was a little old farmer's house with an elderly couple still living there with their chickens and guard dog. I talked to the dog to calm him down and reassured the old man and his wife that I just wanted to take some pictures of the stream. They seemed to relax and waved me through although I suppose they must have been nervous at the sight of a strange, camera-toting foreigner. Sure enough I found the channel, which had been bridged to give access to the fruit trees on the other side...

I crossed the bridge and followed the rough path for a short distance but it turned up onto the hillside and away from the channel so I gave it up and headed back.

I left at about 10.30am because, although I had made mental notes of some other roads to check out further north from Tianliao up into Neimen, I wanted to get back to Tainan with time to take the dogs out before going to work in the afternoon. Those roads can wait for tommorow morning (if I can get up early enough again); the aim of checking them out now will be to ascertain whether, as I suspect, the channel runs entirely underground from the Neimen control gate to the Yanchao control gates, or whether there is some other section of the channel further north which flows on the surface using an existing water course.

Better pictures of the Yanchao control gates will be necessary, and I need to give some further thought to account for the existence of two gates rather than one (though I strongly suspect flood control), but all in all I'm quite pleased with today's little discovery.