Black Hole - "Flashing vs. Flowing"

[rockgremlin]

DAMN!!! What a time NOT to have a camera!!

Last night we camped at the Soldier's Grave on hwy 95. Just before dusk, we watched a pretty intense thunderstorm pass over Cheesebox and Hideout headwaters (both of which drain into White Canyon). We awoke this morning at 6:15 to the sound of rushing water. We peered over the edge of the cliffs, and sure enough, White Canyon was flowing. We originally planned to do the Black Hole today, but since White Canyon was flowing we decided to go down the road and do Leprechaun Canyon instead.

We were in and out of Leprechaun by 12:30. Curious as to the flowrate of water in White Canyon, I decided to check certain spots along it's length on my return trip to Monticello. Here are the results, which surprised me:

1:15 - at the spanbridge over the White Canyon -- DRY!

For about an hour after leaving the spanbridge, I explored some unknown dirt roads in the area of Blue Notch, and also drove up to the Happy Jack Mine. At 2:20, I drove over where Fortknocker Canyon road passes under hwy 95, and noticed that the section of White Canyon at that point was still -- DRY!

Driving roughly 2 miles further down the road, I noticed White Canyon was wet, and flowing. I quickly turned around, and returned to the where Fortknocker Canyon road and hwy 95 intersect, and waited....

Sure enough, the water came. At exactly 2:30 the water reached the intersection of Fortknocker Canyon and hwy 95. It was moving very slowly. I was able to walk up to the edge of the flow, and walk in front of it as it creeped along. Moving at the same pace as the flow, I paced off about 55 - 60 feet in one minute. The flow wasn't carrying any sticks, logs, or dead animals, but it was very warm to the touch -- almost hot, probably around 70 - 80 degrees.

At 2:52, I returned to the Soldier's Grave, and the water was still flowing, but at roughly 75% of what it had been at 6:15 this morning. I also witnessed a Forerunner drive over the flow with no problem, probably en route to Cheesebox or Gravel Canyons.

So apparently, flowing doesn't necessarily mean a deathly flash flood is imminent. We could have been in and out of the Hole today with no problem.

I still think we did the right thing though....

[RAM]

What a great story. The Professor is here (15 time vet of the Hole) and we enjoyed that a lot. FWIW it sounds like the flow you saw was from the day before's rain and if no more was happening today, your descent would have been safe, AFTER you scouted the reality of the flow, like you did. It does narrow down considerably in the Hole section and what is OK at the road crossings, can be fatal in the Hole proper. Experience has shown that the Hole at 5 cfs is pretty manageable. Double that and you could be in trouble. And watch for those follow up surges. They can come in waves, raising and then lowering the amount of flow. An edgy game, for sure. Not a system to mess with. Big scale place. Thanx again for the report
R

[Iceaxe]

Experience has shown that the Hole at 5 cfs is pretty manageable.

The flow at the Soldier's Grave at 6:15 was about 400 to 500 cfs..... it was really rolling and made a thundering sound as it echoed off the cliff's. It was loud enough that it woke everyone up.

The scary part was the sky was cloudless Sunday morning, and was actually only partly cloudy Saturday night. The storm that cause the flash was only about 3 miles diameter and really dumped on one spot for about an 1 hour and then disappeared. If you were not camped within a 10 mile radius you would have never known the storm had happened.

I think from now on for safety I might camp at the Soldier's Grave the night before a Black Hole attempt. If it's dry in the morning you have some safety margin. It was spooky.... We would have never known a flash flood was heading for the hole if we had not camped up stream. We would have had ZERO warning if our timing had of been off.

Lesson learned, that is a scary drainage.

[Iceaxe]

One other thought..... I believe a flash flood loses a lot of energy as it flows down something as big, sandy and wide as White Canyon. That soft sand and wide canyon had to be sucking a tremendous amount of energy out of the flow.

As I noted, the thunderstorm we witnessed was in a small area over a relatively short time span. If you increase the time span or the area of the storm the flash would have contained much more energy and been able to replace what it was losing from its leading edge.

I believe what Rockgremlin saw at Fortknocker was only a remnant of what originally entered White Canyon.

[RAM]

Shane said.....One other thought..... I believe a flash flood loses a lot of energy as it flows down something as big, sandy and wide as White Canyon. That soft sand and wide canyon had to be sucking a tremendous amount of energy out of the flow.
As I noted, the thunderstorm we witnessed was in a small area over a relatively short time span. If you increase the time span or the area of the storm the flash would have contained much more energy and been able to replace what it was losing from its leading edge.
I believe what Rockgremlin saw at Fortknocker was only a remnant of what originally entered White Canyon.


Right you are on all the points. The professor said...."50 gallons in that pothole, 300 in that one. A lot into the sand too, especially AFTER the flood starts to slow. When a flood is ripping, it will create a hard crust over sand and lose less energy. It is only after the pressure lets up that, that more absorption occurs in the sand.
Yup on how dynamic these floods are. If it rains in a more general way, the flood will come through in surges, at different times, reflecting each drainage's emptying out.
The folks in Antelope had blue skies above their slot section.....20 miles away an unseen rain spelled their doom and that is a little system, alternating between wide open Sandy washes and closed in slot sections. Scaaaaary!
RAM
PS Your Cheese footprints are gone, goodbye, are they not?

[rockgremlin]

PS Your Cheese footprints are gone, goodbye, are they not?

Assuming there was flow in the Cheese from that one isolated storm, then yes, our tracks are now long gone.

[James_B_Wads2000]

All you internet blogging dorks down there and nobody had a camera?

James

[Alex]

Actually too many pics.... I sent them to Ice, he can do a full TR with pics. Between Ice and me we had about 200 pics I assume.

I couldn't test my Canon S2 IS camera side by side with my Pentax W10 camera, but everyone on the trip agreed that Pentax W10 camera is the camera for canyoneering, especially if it's a wet trip.

[fourtycal]

Nice pictures, I wish I could have been there, Southeast utah is my favorite corner of the world.