I'm quite busy these days, so I didn't post anything about Hat Creek for World Water Day. Instead, I'll go ahead and post this already standing pre-post. If anyone wants to find out more about water and rivers than the small amount of information written here, I suggest reading posts by Anne Jefferson at Highly Allochthonous, and be sure to check out this video developed by Little River Research & Design. [What I'm busy at is something I can't talk about (as usual), so it won't appear in this month's Accretionary Wedge - the due date is today in case *you* want write for The Wedge.]
Three years ago today, in the middle of a rainstorm turning later to snow, MOH and I went to the Cave campground, located near Old Station, California, right across Highway 89 from the turnoff to the Subway Cave lava tube. We wandered around in the rain, spending most of our time along the banks of Hat Creek, which runs on the west side of the highway. I recently conferred with Anne Jefferson and her students about the picture above, wondering if any part of the picture shows a hydraulic jump. The answer is yes, the whitewater marks locations of hydraulic jumps, in this case several small ones, no large ones. [Photo credit: MOH.]
I learned a lot more, too. We can see a "long tongue of high subcritical Froude" along the right bank. [By convention, the right bank is the one on the right side when you are looking downstream, in this case the bank closest to us.] The subcritical flow regime is indicated by the standing waves just beyond the irregular-looking whitewater in the near foreground. There is also subcritical flow upstream of the log in the center, indicated by bow waves upstream from the log.
Not knowing exactly what I was looking at three years ago, other than a very nice, swiftly flowing stream, I almost missed getting a closer shot of the bow waves, which can be seen here amidst the raindrops. I can identify three waves in this view for sure, possibly a couple others.
And now, looking straight downstream just right of the central log, I've managed to freeze the water motion just above one of the small rapids. The smooth water flows and drops into the whitewater.
Same view with the water action not frozen by the camera. At least two of the bow waves come over toward the center of these two nearly identical photos.
This is a view of a log across Hat Creek; the log was also seen downstream in the last two photos. [Photo credit: MOH.]
This is what Hat Creek looks like in the upstream direction from about the same location: smooth water along the right bank in the foreground, more irregular and choppy-looking whitewater or riffles along the left bank and farther upstream, then more smooth water beyond that just before the stream goes out of view. The rain made the grass stand out, and brought out the reddish tones of the dominantly Ponderosa pine forest.
The region north of Lassen Peak is volcanic, and right at Hat Creek the bedrock is basalt. Here the trees are growing amongst basalt boulders or small outcrops.
By the time we left, it was back to winter again, and we drove away through mostly untracked snow.
For some detail about the isotope hydrology of the region:
Rose, T.P., and Davisson, M.L., 1996, Radiocarbon in Hydrologic Systems Containing Dissolved Magmatic Carbon Dioxide: Science,,Vol. 273, no. 5280, p. 1367 - 1370.
Rose, T.P., Davisson, M.L., and Criss, R.E., 1996, Isotope hydrology of voluminous cold springs in fractured rock from an active volcanic region, northeastern California: Journal of Hydrology, Vol. 179, Issues 1-4, p. 207-236.