Another Verde River photo comparison: 2009-2010

OK, bear with me. this one is pretty cool. My colleague over at AZGS,
Ann Youberg, sent me a photo of the paleoflood study site that she
took on a float trip in April 2009. Here it is compared to the one
that I took last week. Amazing change. Particularly interesting in
that many of mine follow the occurrence of floods, and hers happens to
not follow one. The differences are pretty obvious. Notable is the
removal of an inset deposit (hosting much of the vegetation) that is
likely linked to the 2005 flood. Thus emphasizing the transient nature
of fluvial historical and paleoflood records...particularly the
deposits from low and moderate magnitude flows.

Ann, you really nailed the positioning of the image. Thanks! Next time
you float the Verde, give me a call. I may just drop everything and
tag along.

(download)

Flood features on Burro Creek and Big Sandy River, AZ

Some ephemeral features and some persistent features. For the full
gallery in its geotagged glory check out:

http://picasaweb.google.com/drjerque/BigSandyRiverAndBurroCreek#

Bottom line: Big Sandy had a decent, but not extraordinary flood above
the confluence with Burro Creek. Burro Creek had a notable flood that
buried vegetation along the edge of the channel with sediment and
nearly lapped onto a late Plesitocene terrace. Burro Creek is a
notorious flood machine that drains a very rugged part of west-central
Arizona.

I blew it by not visiting the Big Sandy/Burro Creek confluence.

(download)

18 years of flood-wrought change, Verde River, AZ

This series of photos documents changes that have occurred in a
tributary-mouth slackwater deposit site along the lower Verde River,
Arizona. It begins in 1992 and includes images from 1996, 1997,
1998(2), 1999, 2000, 2005, and 2010. The series includes several large
floods down the Verde as well as a couple of floods down the
tributary. Sadly, I don't have a roughly matching photo directly
following the record flood of 145,000 cfs that buried this site in
sediment in 1993.

The terrace is one of 4 at this site that support a paleoflood record
in excess of 1500 years for the Verde River. The transformations that
this terrace has undergone in the last 18 years, however, supports the
assertion that most (all?) Holocene fluvial paleoflood records are
inevitably incomplete. Note how inset terraces come and go.

We busted our butts getting down to this site last Tuesday...not a
trivial drive after a large flood...and grabbed some data, some
photos, and some new incentive to finally finish our manuscript about
the flood history of the river.

We do have a publication about this site already:

House, P.K., Pearthree, P.A., and Klawon, J.E., Historical flood and
paleoflood chronology of the lower Verde River, Arizona: Stratigraphic
evidence and related uncertainties, in Ancient Floods, Modern Hazards:
Principles and Applications of Paleoflood Hydrology. AGU Water Science
and Application Volume 5.

https://www.agu.org/pubs/booksales/books/HYWS0053541.html

(download)

Verde River, AZ flood update

We have been studying the stratigraphic record of floods on the lower
Verde River, AZ for 17 years. After each notable flood we have
revisited this particular site near Sheep Bridge.

This site has a firm hydraulic control and produces a reliable rating
curve. When floods overtop the surface in the background (behind Phil)
the discharge is greater than 100,000 cfs. Thus, when the gage
reported 115,000 cfs on Jan 21-22, it seemed improbable but the number
meant drop everything and head to the field site. Well worth it.

The river clearly experienced a large, but likely brief, peak over
100,000 and we collected data relevant to finish a paper some 17 years
in the making. The paper compares the historical record to a
paleoflood record more than 2500 years long (based on multiple sites).

Notes:

1. In Jan 1993, this site experienced a discharge of 145,000 cfs.
2. The 'inset' photo' shows the same site in 1998.
3. Conditions remain good for additional flooding.
4. I will be posting addiitional details when I get back from the field.

Imgp4777

2-1-2010_7-21-39_am

Img_5822

Img_5825

Mapping yet another tortured river...the Mighty Bill Williams River, AZ

It is tortured river season in my office. Lately, I have been tackling Nevada's mighty Walker River and its shrinking terminal lake (new term is terminus lake...but that is a bit soft); and Oregon's Owyhee River and its travails with lava and landslides; but now I am back on to the Mighty Bill Williams River of Arizona. You know, the Bill Williams River.

Included below is a snippet of the map I am working on. Shown are 6 generations of lines that document major changes in the channel, most since a dam was finished in the late 60s. One day soon, this map will actually make sense, I promise.

10-30-2009_10-30-57_am

The BWR is a special case. It is a roughly 35 mi stretch of river that traverses the hot desert below the confluence of two rivers that collectively drain more than 5000 square miles of western Arizona. Alamo Dam sits just below the confluence and traps essentially all of the sediment that would otherwise have gone down the BWR and to the Colorado River (well, at least to Lake Havasu). Also important to note is that the pre-dam BWR could attain peak discharges ranging up to 100,000 cfs, whereas the post-dam BWR can hardly exceed 7000 cfs owing to the outlet works of the dam. Thus, large runoff events that would have otherwise blasted through the system in a week or less (Spikes) are now converted to protracted, flat-topped hydrographs that lumber through the channel for up to several weeks to months (Bricks). Recall that these bricks are also sediment-free except for the sed picked up in the channel below the dam.

The result is an interesting experiment in channel change, sediment budgeting, and inadvertent (or otherwise) tamarisk farming. 

I won't be posting daily updates of this map, so don't worry. Be assured, however, that I will make a lot of noise when I finally finish it. This one is a long, long, long, time coming. Just ask the sponsors.

Some other BWR info: 

More LiDAR...different river

Another example of the of the standard hillshade vs. 'isotropic' hillshade (isoshade) concept previously described with reference to the Owyhee River, OR. These are from a couple of reaches of the the Bill Williams River, AZ. The BWR data set is fine until the trees get in the way. Both image variations are pleasing. The standard hillshade looks 'natural' but the isoshade image reveals more intricate details.

(download)