A Brilliant Morning At The Li Xi Weir In Wuchieh, Nantou County

Myself, on the south side of the Li Xi stream across from the weir and entrapment pen which diverts water to Sun Moon Lake.

It's Chinese New Year, which means a week off work. Obviously on Sunday morning there was the earthquake which caused that disaster here in Tainan, and that day's trip to Nantou was a write-off anyway due to the fog. The weather on Monday was brilliant but I stayed in Tainan for a barbecue. The weather forecast predicted the same brilliant sunshine for Tuesday and then cloud for the rest of the week, so I decided to try the Nantou trip again on Tuesday. And it worked out very well...

What I had planned to do, in order to make the most of the time and sunshine, was to take the midnight train up to Ershui and drive through the night into Nantou, rather than wait for the first morning train which would have delivered me into Ershui as late as 9.30 a.m. (assuming no delays). However, when I told Karen my plan, she demanded to come too, which meant negotiating some conditions: an early start, me picking up my motorbike at Ershui, and splitting up when we got to Wuchieh. The problem is that, having done it once in the fog and rain, I have a fearful regard for the approach road to Li Xi weir because it is narrow, with a precipitous edge of maybe five hundred meters, in bad condition being constantly eroded by several areas of falling water, has few passing places and is subject to periodically falling rocks much more so than other roads so advertised. I trust myself on a motorbike up there, but even then I am very wary. The local aborigines organize tourist trips to the weir using their (frankly brilliant) Mitsubishi Delica 4x4s, but I wouldn't fancy that road in any sort of normal car. No chance.

Besides that, I love being on my motorbike up in the mountains...

On the way up from Shuili, we made a brief stop at Minghu reservoir so I could show Karen and explain to her. There was also a stray dog there; I fed him a couple of packets of beef jerky.

The sun peaking over the mountain ridge at sometime after 8 a.m. Karen took this and the previous picture. Rays of sunlight are good, but they can obscure the main object of the picture which is in this case the Minghu dam.

On the mountain pass well above Wuchieh village just after 10 a.m.. The concrete arch bridge in the distance was one of two structures I had come to take a closer look at; it carries water left to right from the Li Xi weir through a tunnel to Sun Moon Lake. The natural beauty of this area is typical of much of Nantou County beyond the little towns like Puli.

Focus on the bridge using the 18mm lens. The first time I saw this bridge two years ago I mistook it for a road, as probably many people have done previously.

Then the eagles arrived. One observation I have made on my travels is that, in the mountainous areas south of Taichung you can have a reasonable expectation of seeing several of these birds, but Taichung and north until you get to Taoyuan County, not so much (I have seen several at Shihmen reservoir). I had previously thought they'd be easy to spot in Taichung, Miaoli and Hsinchu counties, but either I wasn't far enough east (unlikely) or they simply aren't there. 

One of the difficulties of photographing eagles in flight is focus; you cannot rely on automatic focus because the mechanism is too slow and there is the chance of focusing on a tree branch or something, so you have to use manual focus which is especially difficult because the birds are in motion and you are making adjustments to try to get it exactly right all the time. Still, even when a shot isn't quite in focus - as is the case here - I still get something out of looking at it.

Better focus on this shot, but a second problem: light. The problem here is that to avoid a washed-out sky, you reduce the exposure value, which then makes it difficult to capture the subtle differences among the bird's darker colours.

Banking; my second favourite type of shot (after the perched shot) is to get the bird banking with the back of its wings fully exposed to the lens; I haven't quite managed it here, but it was close.

Unbeknownst to me at the time, Karen was not taking pictures of the valley, but of me. When the eagles came, her Sony smartphone camera went from being very good to completely useless. It's better than mine, but that isn't saying much as mine is a cheap and cheerful Taiwanese HTC which I use for "I'm going to the park..." type messages.

Examining the image display. 

Eventually, the eagles began to get closer to our position on the road. This is possibly the best pick of the morning; the focus is on the right wing rather than the bird's face, but otherwise a good shot.

The most amusing problem is when the eagles actually get too close to focus properly on them. I'd like to think this is evidence of eagles having a sense of humour and purposefully taking the piss out of photographers.

Not too bad; some light to illuminate the far side of the right wing and the upper-left side of the body, but not quite enough to show off the whole bird. The yellow bill has too much light. At least you can distinguish the browns from the blacks along the body, tail and wings. 

When we got down into the village, I took Karen to the path toward Wuchieh reservoir and left her there to walk her dog and look around while I went off to get what I came for. The first thing was to get some close up shots of the suspended tunnel across the Zhuoshui river which is part of an otherwise underground diversion tunnel transporting water from the Li Xi weir to Sun Moon Lake. It replaces the old Japanese tunnel which had previously filled up Sun Moon Lake with water entirely from Wuchieh reservoir.

The spectacular concrete arch which supports the pipeline as it passes over the river from one section of tunnel to another. Given that it was built in 2006 (seven years after the deadly earthquake that hit Nantou in 1999), it should be interesting to learn about its' construction methods and what was done specifically to "proof"  the arch from collapsing when a large earthquake occurs. 

There are two Chinese language signs there which give some information about the construction method for the diversion tunnel and the concrete arch bridge; the tunnel was made using an expensive Tunnel Boring Machine (TBM) by The Robbins Company based in Seattle (this was something I already knew) and the bridge for the tunnel was made using "concrete lapping method with pre-erected composite arch" (or CLCA). It turns out that this is a method for making permanent falsework. The initial arch is made out of steel tubes which are then filled with concrete to act as falsework to build the rest of the bridge around. In this case they'd have started with parallel tubes filled with concrete and then used more steel tubes to form reinforcing boxes between the two parallel arches, and then filled these boxes with concrete. So... you've got an arch made out of steel reinforced concrete based on concrete-reinforced steel arches.

The other panel giving further information which I'll have to have translated to find out if it's interesting or not.

The concrete arch bridge in perspective, shot using the 10mm lens.

Close up shot of the other side using the 300mm lens. Note the series of steel ladders and platforms on the mountainside.

The arch, bottom left, followed by three Addidas-like concrete support columns and the concrete abutment on the other side with stairway and railings.

Close up on a section of the pipeline supported by the bridge; there is a narrow gangway on each side supplemented by lamp-posts and a ten-foot fence with barbed wire at the top. Why that was thought necessary I'm not sure because it's not obvious how anyone without a James Bond skillset (and budget) could get anywhere near it. Or were they worried about inexplicably suicidal engineers attempting to jump to their deaths? Or maybe one of the chief engineers just thought a barbed wire fence would look cool. Who knows?

The second of three adit points, this is Adit B which is level with the pipeline. Adit A, which is below the pipeline, is further back down the approach road  and just up from Wuchieh village, and Adit C is on the other side of the river well above the tunnel. They are basically access points to allow assessment and repair of the pipeline whenever there's an earthquake.

Overlooking the concrete arch and pipeline from the precipitous approach road to Li Xi weir.

Note the use of steel housing for the pipeline on the west side of the river which is to protect the pipeline from falling rocks. However, the obvious questions are (a) why isn't there a similar housing  for that section of the pipeline on the east side of the river, and (b) why isn't the entire pipeline covered with such protective steel housing in the event of high winds and rockfalls? It could be that there is a legitimate risk-analysis reason for this, or it could be that there is an engineering reason for it, having to do with the additional load stresses placed on the arch, or it could be insufficient funds. 

Leaving the concrete arch and pipeline behind, I followed the narrow approach road to the Li Xi weir. This was only my second visit and this time the weather was absolutely perfect, though it is still a very dangerous road. When I arrived at the widened section of road leading up to the weir, I parked my motorbike and took my kit with me over the wall, scrambling down a shale slope to a concrete ledge running parallel to the walled road. Toward the end of the road I noticed that there was a group of families already on the river bank messing about; they had got there by means of a gated ramp I hadn't noticed on my previous visit. I jumped down and approached them, saying hello and happy new year and began taking pictures of the weir. They all promptly left on my arrival which I presumed without thinking was because they were already going to leave anyway. But maybe I just looked a bit odd with all my kit.

On the northern shoreline looking westward toward the weir; the stream is relatively shallow and very fast as you can see from the white heads of the rapids. Further down closer to the weir and just after the last of those foaming white waves, I found the shallowest spot I could find and waded across. The waterproof material of my boots didn't matter because at several points the water rose half way up my shins and flooded the boots anyway. It was a small price and worth paying, but I should have brought my water-shoe sandals along specifically for this.

On the southern shore looking westward toward the weir gates and entrapment pen where water from the Li Xi stream enters the pipeline to be carried to Sun Moon Lake.

Close up on the entrapment pen gates; in addition to the outside grille, there is also an inner grille to prevent debris from entering the tunnel and you can see some of it floating about inside.

An even closer shot shows that the debris is mostly broken bits of driftwood, which is what you'd expect given that tourists who come to the weir tend to be few in number and those of them who get down to the riverbanks will be even fewer still.

Close up on the weir gates.

Standing on the weir lip looking upstream at the on-rushing rapids before they reach the concrete box for the water to be calmed before passing through the grilles for the entrapment pen.

The sedimentation tank beyond the entrapment pen; this is where the water from the stream, likely already very clean, is stilled so as to allow fine particles to settle to the bottom of the tank before entering the pipeline. The original Japanese diversion tunnel from Wuchieh reservoir had no such tank and the Zhuoshui river is Taiwan's largest river containing vast amounts of silt. Hence the erosion of the original Japanese tunnel and the necessity of its replacement with the pipeline and tunnel from Li Xi stream.

Looking downstream from the lip of the weir; the channel to the right is what lies behind the weir gates, and whilst some small amount of water is allowed through to maintain the stream as it winds its way down to enter the Zhuoshui river, there is also some additional water added to it from a small portculis to the side (and bottom) of the sedimentation tank to take away sediment-filled water. 

One last parting glance back upstream at the Li Xi; aside from the weir, the valley is utterly wild and unspoiled and is home to a number of protected species. A really beautiful area.

When I was finally done (at about 11.00 a.m.), I crossed the stream again and made my way up the narrow ramp and through the twisted metal gate, and lobbed the wall. The two poor, underfed guard dogs who are permanently chained up there barked nervously at me once again, and like last time I fed them some of my beef jerky - of which I had more than enough this time (they got three packets each, and I would have given them more but I didn't want to upset their stomachs with what is actually fairly rich meat). I tried waving to get the attention of staff inside the building to see if I could talk to them and get them to let me enter the premises and take pictures of the sedimentation tank, but I couldn't get their attention. They were probably watching TV. So I squelched off in my water-filled boots up the road to get my motorbike and drive back up to Wuchieh to meet Karen and drive back to Ershui. On the way, we passed by Minghu and Mingtan reservoirs once again, and with the weather being so good, I went back briefly to take a wide-angle shot of Mingtan from the road running past it on the west side...

The oddly shaped Mingtan reservoir.

There are still a few more things I want to do in Nantou, but I'm not sure how feasible some of them are. At any rate, my time in Nantou will be coming to an end soon, and then I will have to make a choice between moving the motorbike northwest back up to Hsinchu, or northeast up to Hualien. A decision that doesn't have to be made yet...