|Posted: Jun 13, 2006Post Subject: Meral's Pool put-in gage ... reading low?
|Has anyone noticed the put-in gage at Meral's Pool is not accurately correlating with the reported Dreamflows charts this year? The discrepancies get exponentially larger as the flows increase from appx. 6000cfs and are significantly mismatched in the 10,000cfs range. After a few conversations with Chris, I will try and be "succinct".
On a 2-day trip, June 3-4 '06, I estimated the flows to be 5800cfs (Sat. 3rd) and 6400cfs (Sun 4th), by reading the gage at Meral's put-in. Upon return home and checking DFlows they showed the flows to be appx. 6800cfs on Saturday and 7500 cfs on Sunday for the correlating time periods.
On a 2-day trip, June 10-11 '06, I estimated the flows to be 9900cfs (Sat. 10th) and 9600cfs (Sun. 11th), by reading the gage at Meral's put-in. Upon return home and checking DFlows they showed the flows to be appx. 13,500cfs on Saturday and 13,000cfs on Sunday for the correlating time periods.
From past experience and corresponding gage readings for that time period, I personally thought the river was running around 7,000-7,500cfs in example #1 ... and 12,000-12,500cfs range for example #2. I have more trips under my belt at these higher flows over the years than I'd care to admit ... if you'd like to compare historical notes and want the "Long Version" of my observations ... like what flow the traditional "Clavey Hole" begins to "flatten" ... out ... it might be kinda fun
Sooo ... what gives??? ... Due to Chris' exhaustive research , I think Dreamflows is more accurate than the present put-in gage at Meral's Pool! ...
|Posted: Jun 13, 2006
|Well, most of the Dreamflows estimate is the sum of Cherry Creek - Rel Holm Powerhouse and Tuolumne - Below Early Intake. The rest is an estimate for the contribution from the SF and MF Tuolumne, however that's usually low compared to what's coming down the main, so the estimate should be pretty good (always assuming the above two gauges are accurate, of course).
What I heard after the '97 flood, from friends who worked in Yosemite and for the F.S., was that the dude who pounded the stick gauge back in forgot to take the SF and MF Tuolumne flows into account. Guess he didn't pound the stick in far enough. If true, that would also explain the exponential error - at low flows a few inches aren't so noticeable, but at higher flows a few inches of error become significant.
|Posted: Aug 23, 2007Post Subject: More On Meral's Staff Gauge
|I also think the Meral's gauge is underestimating, based on my experience this week. On 8/21 we launched on what should have been 1200 cfs -- 1100 from Holm PH plus 80 on the main stem below early intake. However, the staff gauge at Meral's showed about 4.95 feet after the water came up. That would supposedly be less than 900 cfs, according to the conversion table posted at put-in. Chris's theory that the gauge didn't get pounded in far enough after the '97 flood makes sense. If so, seems like boaters could mentally "recalibrate" the staff gauge by just adding an inch or two to the reading. Unfortunately, I didn't look at the conversion carefully to figure out how many inches you would have to add to come up to 1,200 cfs.
|Posted: May 20, 2008Post Subject: gauges...
|My understanding is that the gauges at Meral's Pool were damaged in the '98 flood. None of the commercial guides rely on that gauge. Hope that helps.