Editor's note: As is sometimes the case, this is a two part story that Satoshi shared with us. This first part is published to the front page. To read the rest that follows in his next post, become a member of smallstreams.com and join us in the forums!
The right hand photo was taken just a few hours after the left was taken in the same stretch of a stream. Do you believe if I say the change in the water level from left to right occurred within almost 5 seconds?
Thatís exactly what I saw.
From September 11 to 15, I went to Tohoku region for fishing, staying at my regular inn, Kubota lodge. The trip has been one of my annual events for these several years.
I arrived at the lodge at around 4 PM, and immediately went to a nearby river to wet the fly line.
Though the fish were not very active in that evening, I managed to catch one yamame, and lost another.
In the next morning, I went to a stream that is around 30 minute drive from the lodge. In the morning, the weather report said the probability of rain was 50% in the area, but even if it would rain, it would not to be very heavy. I had been told the place was an excellent fishery, but somehow I hadnít had a chance to fish the stream.
The stretch of water I was going to is marked by two water diversion dams at its upper and lower ends. The dams are for an electric power plant. The water pipe in the above picture leads you to the dam and the power plant at the lower end of the stretch. There are concrete steps along the pipe, which further go down to the dam from the far end in the picture. The stretch is called ď600 stepsĒ, because there are about 600 concrete steps along the pipe. When you fish this stretch, you go fishing upstream to the upper dam and walk back along a road that was built to maintain the facility, and come back through the 600 steps again to the parking.
This is just above the lower dam. They say the water level is usually low in this stretch because the water is diverted by the upper dam. For about the first 100 meters, I caught only 2 fish, but then, fishing became heated up as I went upstream. I started to catch iwana from every small holding water. The sky was overcast with intermittent sprinkles.
The fish were not particularly large. Most of the fish were around 8-10 inches, but they were very active.
They readily snatched the fly as soon as it landed on the water.
However, the rain gradually became heavier, and I also heard rumbling thunder, although I kept catching fish.
A while later, it began to rain so hard that I even couldnít take my camera out. The water became a bit discolored, and the fish stopped responding to my fly. I stopped fishing and checked the topo map. I didnít know exactly where I was, but the lower half of the stretch was surrounded by steep walls of mountains whereas the slope was gradual in the upper half where the road paralleled the stream. So, I walked upstream hurriedly, not only because fish stopped rising, but there was a danger of flash flood in such a deep slot canyon like this one.
The color of the water then turned to reddish brown, though the water level didnít rise much. This is the sign of an immediate danger, because the watercolor meant soil had come into the stream, which further meant a land slide had occurred somewhere upstream.
If a land slide occurs in a narrow canyon like this, the debris often blocks the stream, creating a temporal natural dam, which eventually collapses and releases the pooled water as a flood. I had read these knowledge in books, but, of course, I hadnít encountered such a flood by myself.
Within 30minutes after I stopped fishing, it stopped raining. The clouds became apparently thinner and I didnít hear thunder any more. I felt relieved. Then, I saw the canyon was filled with a muddy turbulent rapid, perhaps 100-200 meters upstream of me. It was very strange, because the stream water occupied only a small part of the streambed where I stood. At first, I thought there might be the upper dam there, but I couldnít see any such structure. Then, after a few seconds, I realized it was a flood which is actually coming down rapidly to me. I panicked a bit. I bumped my head with a large log when I tried to cling on the bush of the streamside. I guess it took 20 to 30 seconds for the flood to come, and I had time to climb up to a safe place before the flood reached the place where I had been standing. Within 5 seconds, the flood filled the entire bottom of the canyon. I was lucky, because the stream was straight there, so that I could see the flood well in advance. What if the stream curved and I couldnít see it coming?
I climbed the slope through bush for only about 20 or 30 meters to get to the road, along which I walked back to the entrance point.
When I came back to the lower dam, it was flooded with muddy water.
At first, I thought the flood was caused by the collapse of a natural dam created by a landslide. However, the water level didnít decrease after the first wave of the flood had passed. On the contrary, the water seemed to increase gradually. So, I canít tell exactly what happened upstream. The upper dam is just a small water diversion dam and doesnít have a mechanism to release its water. Anyway this was an invaluable experience for me.
....to be continued to the next post