Adopt A Beach:
Long Term Monitoring of Camping Beaches in Grand Canyon
Summary of Results for Years 1996 – 2002
The Adopt-a-Beach (AAB) program has completed its seventh year as a study
that monitors annual camping beaches in Grand Canyon. This program, sponsored
by Grand Canyon River Guides, Inc., is implemented by a 100% volunteer
force of river guides, scientists, and NPS personnel. Results are submitted
to various agencies such as the Cultural Resources Program of the Grand
Canyon Monitoring and Research Center (GCMRC). Results are also presented
to the Adaptive Management Program so that private and commercial recreational
interests are represented as stakeholders in Colorado River management
as reported to the Secretary of the Interior.
Adopt-a-Beach is a program of repeat photography that documents the changing
conditions of a selected set of Grand Canyon camping beaches from April
through October of each year. The selected beaches lie within five critical
reaches of the river corridor. A critical reach is defined as an extended
area in which camping beaches are sparse, small, and/or in high demand.
The program assesses visible areal change to beaches resulting from changing
regulated-flow regimes, rainfall, wind, and human impacts. Volunteers
for this program are unique in that they run the Colorado River many times
in one season, and they are able to provide sets of repeat photographs
for each study beach. To date, guides have produced over 1,000 repeat
photographs and associated field sheets having recorded the sequential
condition of beaches throughout the commercial boating season, year after
year. Research results include: 1) total cumulative change to beaches
after a summer season and the processes that affect change, 2) change
to beaches after a winter season, 3) longevity of the 1996 beach/habitat
building flow (BHBF) deposits, 4) change in campsite quality throughout
the summer season, and 5) areal change to beaches following any experimental
The most recent high flow experiment of 30,000 cfs, was conducted during
fall of 2000. To date, this deposit is either very narrow and thin, or
no longer exists on campsite beaches. The primary cause of erosion, reported
by guides for river season 2002, was the moderately high fluctuating flows
of 10,000-18,000 cfs throughout July and August.
The most significant event recorded by guides was the small beach-building
event caused by the Little Colorado River (LCR) flood in early September
2002. Morphological changes resulted in new low-elevation benches (around
the 20,000 cfs zone) and sand bars that covered pre-existing gravel-and-boulder
bars. The combined mainstem with LCR flood peaked at about 22,000 cfs.
The resulting beachfront deposits suggest that a coordinated mainstem
spike with an LCR flood can be very effective in building beaches or low-elevation
The longevity of the BHBF deposit since 1996 shows varying results. As
of fall 1999, 59% of camps had returned to their pre-BHBF condition (O’Brien
and others 2000). Results of the 2000 HMF flows showed that 78% of beaches
were again larger than their pre-BHBF condition, within the 20,000 to
30,000 cfs zone. Then by September 2001, 45% of the adopted beaches had
returned to conditions similar to that before the BHBF. Campsite areas
within the 30,000 and 45,000 cfs zone have continued to decrease overall
throughout the years. At least 30% of beaches have apparently developed
quasi-stable deposits within this zone, as they show no to very little
The Low Steady Summer Flows (LSSF) of year 2000 provided more diverse
camping, both upstream and downstream of campsites within the study set,
and within the campsite itself, according to guide response for 31 beaches.
The combination of the HMF followed by the LSSF proved beneficial to 78%
of all studied beaches.
These results contrast with those of the 1999 river season, during which
a high percentage of beaches lost area due to flash floods, and a small
percentage were affected by fluctuating flows. Before 1999, beaches had
been eroding at a decreasing rate, mostly from fluctuating flows, as reported
by guides and supported by visual cutbank retreat in photographs (O’Brien
and others 2000). Typically, rapid adjustment of newly aggraded beaches
to fluctuating flows following a high release leads to initial high rates
of erosion. These rates then fall off over time (Hazel and others 2001).
According to many guide remarks, campsite beaches were “primed and
ready” for the HMF and LSSF regime of 2000. Then by September 2001,
guides reported that camping had become harder on about 50% of the beaches.
This loss of campsite quality directly relates to beach erosion. Other
reported influences include tamarisk encroachment.
These results suggest that any newly deposited sand will be quickly eroded
if subsequent high fluctuating flows are released from Glen Canyon Dam.
This was evidenced by 3 events: 1) High steady flows (of about 27,000
cfs) following the 1996 BHBF eroded much of the new deposit at all beach
sites through the summer of 1996 and 1997; 2) High fluctuating flows following
the fall HMF of 1997 stripped away the new deposit entirely by spring
1998; and 3) Medium fluctuating flows following the fall HMF of 2000 eroded
most of the new deposit by spring 2001. To date, at least 30% of beaches
still show evidence of high-elevation sand (above 30,000 cfs line) deposited
by the 1996 BHBF. However, the amount of sand appears to be diminishing
from year to year. Annual implementation of HMFs in spring and in fall
would help preserve this deposit by maintaining the beachfront. A regimen
of Beach Habitat Building Flows followed by low fluctuating flows is needed
periodically to rebuild campsite areas above the 30,000 cfs line. However,
future BHBFs need to have enough sediment in the system so as to preserve
Marble Canyon beaches and lessen impacts on lower beach areas (below the
20,000 cfs line) systemwide.
For questions or comments please contact Kate Thompson or Lynn Hamilton
Grand Canyon River Guides, Inc., Flagstaff, Arizona (928) 773-1075.