Adopt-a-Beach Update
Sometimes it gets frustrating
to adopt and monitor one of these “sons of beaches” (referring
to the new generation of beaches since the closure of Glen Canyon Dam).
Many of our precious beaches have been reduced to piles of boulders interspersed
with sand, or they are smothered with tamarisk thickets. Big white sandy
beaches seem to be a thing of the past in Grand Canyon, but have faith.
Year 2003 holds some hope for bringing back some of those camping beaches
or parts of them, as the Bureau of Reclamation is on board for another
so-called “flood flow,” pending approval by the Secretary
of the Interior. This flood flow would be much like the 45,000 cfs release
in 1996. This one, however, is planned to be of shorter duration and is
slated for much earlier in the year, like in January.
The last “flood flow,” or Beach Habitat Building Flow of 45,000
cfs in 1996, tremendously increased beaches throughout the corridor, but
only temporarily. Since then, sand from this deposit has been continually
reworked into the river or blown further up slope. So, we (the collective
we of stake holders, managers, and tax payers) will try our hand at playing
God again with the impending flood flow tentatively scheduled for January.
In light of all the flood talk out there, I figured a brief summary of
Adopt-a-Beach results since 1996 will remind us of the need for periodic
Beach Habitat Building Flows (bhbfs or flows exceeding power plant capacity),
and yearly High Maintenance Flows (hmfs or high flows within power plant
capacity).
How many beaches increased in size following the bhbf of 1996?
Photos from post-bhbf of 1996 show beachfronts and camping space up to
the top of the newly formed deposit. Over 80% of all adopted beaches increased
in size, mostly gaining in elevation. Three beaches showed a net loss
in area: 110-Mile Camp, Ross Wheeler, and Upper National. Even here, parts
of beachfronts and sandbars were removed, but the camp above about 31,000
cfs gained sand and increased in elevation. Two critical factors impeded
a potentially higher net gain from the bhbf: (1) the sharp drop off in
flow from 45,000 cfs to 8000 cfs overnight; and (2) the long-duration,
high-fluctuating flows (up to 28,000cfs) that followed the bhbf and continued
through summer of 1996. These combined factors resulted in huge cut faces
of beachfronts that calved off all summer long, vastly reducing the area
of the new deposit.
How long has the bhbf sand deposit held up on beaches?
To date, portions of this deposit can be still identified in the field
at each site on most beaches. But it does not show up well in photos any
longer, due to reworking of the deposit and mature established tamarisk
blocking the views. Most beaches lost a majority of this deposit by fall
of 1997. Results for 1998 and 1999 show a sustained number of beaches
losing sand. By fall 1999, over half of the beach sites had returned to
their pre-bhbf condition (at least up to and somewhere beyond the 30,000
cfs line, as determined from photos). Secondary causes to decreased beach
size included gullying and flash flooding from rainfall and reworking
of sand due to campers, according to guide responses.
Is there still evidence of spike flow deposits on beaches from year 2000?
The High Maintenance Flows (hmfs) of year 2000 helped replenish sand to
beachfronts, but only to the extent of the hmf flows’ limited stage
heights of 30,000cfs. By fall 2000, 78% of beaches were again larger than
their pre-bhbf condition. This indicates that hmfs are beneficial to maintaining
campsite area, as long as fluctuating flows remain low.
A year later, by fall of 2001,
most of hmf deposits had been eroded to the extent that 45% of beaches
had again returned to their pre-bhbf condition. Hmf deposits last as long
as Glen Canyon Dam can keep flows below about 15,000 cfs (estimated from
guide responses, repeat photos, and analysis of hydrographs surrounding
the 1997 and 2000 hmfs). In conclusion, beaches need temporary high flows
on an annual basis, given there is enough sediment in the system. What
flow regime provides the best camping?
The 8000 cfs constant flows of summer 2000 took the cake here. During
the Low Steady Summer Flows (lssf), guides reported that 77% of beaches
showed much improved camping, in terms of useable space and accessibility.
Camps contained either more sandy beachfront property, decreased rockiness
for better boat parking, or a relatively flat bench for reliable kitchen
set-up and sleeping during the hot season. Guides also commented that
many more beaches became available for camping, such as Clear Creek, Olo,
and Talking Heads, that would otherwise have been extremely small or under
water with higher flows. Conversely, flows during summer of 2001 fluctuated
between 7000 and 14,000 cfs, which made camping comparatively harder due
to decreased and unreliable camping area.
How to find more information?
For further clarification of the methods and analyses employed in this
study, please refer to the forthcoming final report of the 2001 Adopt
A Beach Program. As always, it will be sent to adopters who request them,
appropriate agencies, and other interested parties. Call Lynn Hamilton
at the gcrg office, or download an Executive Summary from http://www.gcrg.org/aab/ab/htm.
Remember that part of our duty, as guides, is to voice our concerns to
land mangers about preserving and enhancing what beaches are left. Adopt
a Beach offers this opportunity as a collective voice. Our little program
does make a difference to the big picture. Get involved and sign up for
a beach today.
The folks who helped keep Adopt a Beach going this year include (in alphabetical
order): Lynn Hamilton, Abigail Sullivan, and Kate Thompson. Thanks to
Andre Potochnik and Matt Kaplinski for representing the recreational interests
and results of Adopt a Beach to interested managers (that would be the
Adaptive Management Work Group and Technical Work Group). We especially
thank everyone who adopted a beach in 2001 and all of you who signed up
for the 2002 season. It’s a great way to give back to the place
we all love. And, please, we still need more adopters! Just give Lynn
a call and she will send out a packet in time for your next river trip.
This program is completely dependent on your participation, and the results
that have been directed through the Adaptive Management Program are due
completely to all of your hard work in photographing and commenting on
the condition of our camping beaches year after year. Finally, we extend
our gratitude to our contributors: the Grand Canyon Conservation Fund,
a non-profit grant-making program established and managed by the Grand
Canyon river outfitters; the Grand Canyon Monitoring and Research Center,
for their dedicated support of this program; and all individual contributors.
Kate Thompson
