Flash Flood Awareness (for the coming Monsoon season)

[ratagonia]

My fellow guide at ZAC wrote this up for a different context, but I thought it was so good it should be shared with the group (vis a vis the coming monsoon season):

I feel like surviving a flash flood comes down to 3 things:

1. realizing that there is nothing any of us can do to eliminate the risk completely

2. preparing / learning / studying as much as you can in advance to help you manage the risks while you are in the canyon / drainage

3. being highly aware of everything around you during the trip, and taking prompt action to escape floods

What is flood water like? Imagine a torrent of water, loaded with sediment, sticks and debris that feels more like concrete, than water. Flood waters easily move hundreds of pounds of dead logs. They have been known to move houses off foundations, and carry cars hundreds of yards, and even miles.

Trip Planning:
1. How does flood risk change with respect to month, week, season for your destination?

2. How many square miles, acres, etc. does the canyon drain?

3. To what degree can precipitation be absorbed by the watershed area? (is the canyon rim made of rock? are there plants / grasses that will absorb some of the falling rain)? In a canyon surrounded only by rocky, low-water-absorption terrain, there is often a significant problem with water running down the walls and the complications this creates by adding more volume to the flood water, complicating escape routes, making use of escape routes more difficult, washing rocks in on top of hikers off the rim.

4. To what degree has it rained there recently? In the sandstone areas, a lack of rain in May, June and July causes the sandstone to become baked like clay, and not able to absorb falling rain in the summer like it does when precipitation falls more frequently, in smaller amounts in the winter.

5. How committing is the drainage? Is the whole hike in the canyon? Does the canyon have wider, open sections, or is it narrow and slotted the entire time? Where is the most committing, least escapable section? Can you identify escape routes on the map? Can you determine if there are escape routes by reading guidebooks, or talking to people who have been before, can you get info from internet canyon groups? What are the logistics / skill sets involved in these escapes? Can you and your group pull them off, or do they involve equipment and skills you do not or will not have?

6. Make sure you allow an appropriate amount of time for your group to complete the trip. Building in extra time can be very helpful. Just because you read in a book that "the author completed the hike in 7 hours" does not guarantee that you won't need 10 hours.

7. Choose a starting time for your event that helps you best manage rain risk and being seriously committed. Often, in the Southwest Desert, the period between July 15-September 1 brings the possibility of a heavy, isolated thunderstorm each day. Starting early, and finishing the trip by 2-3PM helps hikers avoid being in drainages during the time of day when the storm risk is highest.

8. Learn how high the water does / can get in the canyon/drainage during a flood.

9. Consult experts, Gather information, and set a personal threshold for a forecast that you consider "more dangerous" than acceptable in advance. This helps you avoid minimizing real risk, succumbing financial, peer, or logistical pressure and convincing yourself "i'm sure it will be ok" when the forecast is truly marginal or unfavorable. Prepare yourself and your group for the possibility that weather can cancel the event at any point.

10. Check the forecast as close to departure as possible.

11. Understand signs of flooding. These could be:
-thunderheads building
-rain falling
-water starting to flow
-flowing water becoming discolored: red, brown, black, muddy as it fills with sediment
-debris being washed down the drainage: trees, logs, sticks, leaves,
other hikers
-sometimes folks hear a rumbling, thunderous sound as flood water
approaches. I can tell you that people are often unsettled when they hear jet airplanes above them, while being in canyons, as they think this could be the sound of flood water.

While you are in the canyon:
1. Continue to evaluate weather at all times.

2. Look for signs of how high the water reached in past floods to help you understand how high you would need to climb to be above flood water (wedged logs, sticks, grasses and dead plants wrapped around things in the direction water travels).

3. Keep all group members informed. Discuss what you might have to do to escape a flood before you need to do it.

4. As you travel, look for possible escape routes, store them in the back of your mind. Retreat back to a place you have been is sometimes better, especially if there is a known, useful escape. Heading further into in the canyon into territory you haven't seen often brings no guarantees. If you travel past major obstacles that eliminate your ability to retreat back to an escape route, keep this in mind.

5. Look for signs of flooding described above. Take action promptly if you feel like a flood is developing. Avoid a "well, that is only one of many signs of flooding we are seeing, let's just wait and see" approach. Work together with group members. Sometimes climbing a few feet makes a major difference.

6. Wait out the flood on the high ground. This can take several hours, and occasionally, even days.

Hope this helps,
Take the Best of Care

Dave Buckingham
Zion Adventure Company

[abirken]

I think this is fabulous information especially to the Noobs (me). Going to print this out. Thanks for the info!! Very useful.

[rockgremlin]

I think this is fabulous information especially to the Noobs (me). Going to print this out.

Just make sure to study it BEFORE you find yourself in this situation!

[abirken]

I think this is fabulous information especially to the Noobs (me). Going to print this out.

Just make sure to study it BEFORE you find yourself in this situation!

HAHA!! I will! I will! I'm very good and following direction.

[Don]

-debris being washed down the drainage: trees, logs, sticks, leaves, other hikers

[DWayne27]

great information! very helpful...
also found this

http://www.canyoneering.net/docs/canyoneering.pdf

good info about flash floods towards the beginning, and lots of other good stuff too.

[akabennett]

We got caught in a minor flash flood in Spry this past Sunday just after the final narrows. We were up high and safe. It was amazing to experience. Thought I would include a few photos.

[Iceaxe]

[color=darkred][size=6][b]

[oldno7]

Those are great shots. Bet your glad you weren't threading the rope in the small hallway up above when this hit.

[akabennett]

Could have made for a bad day. It hit about 20 minutes after we were all down from the hallway

[kaptain]

Great pictures

[Jaxx]

bennett, that is some awesome action!

Whenever I'm *caught in a flash flood I just do the backstroke. Just like when Im in an avalanche.

*I have never been caught in a flash flood