This is my attitude as well. But, I attended a presentation by
Ned Andrews of USGS, the principle investigator on the "flood"
project, where he said that the sediment balances indicate that
the GC is still gaining sediment. The rate is low, particularly
above the Little Colorado, so it could be overwhelmed by the
downstream transport during a "flood". The net effect of "flood
prescription", it seems to me, would be relatively stable
beaches in the lower reaches with increasingly smaller
beaches as you move upstream.
I think lots of beach erosion is caused by wind--witness the
rapid deterioration of the upland beach at Tapeats. Having
thought about this, I am reconsidering my earlier point,
that we should see perched remnant beachs from super-extreme
flows (c. 800k cfs, 1400-year return interval). They would
quickly blow away. But, fancy micro-crystal analysis might
still detect traces of sand derived from rocks in the upper
basin in locations where the only explanation is an extreme
flow. Look in wind- and runoff-sheltered areas at elevations
consistent with flows between 300k cfs and 800k cfs.
Ben
-- -------------------------------------------------- -- Ben Harding blh@hydrosphere.com -- -- Hydrosphere Resource Consultants -- -- Hydrosphere Data Products -- -- 1002 Walnut, Suite 200 -- -- Boulder CO 80302 -- -- -- -- 303-443-7839 voice 303-442-0616 fax -- -- -- -- Publishing Natural Resources Data on CD ROM -- -- Consultants in Natural Resources Planning -- -------------------------------------------------- ==================================================================== To subscribe, send email to majordomo@songbird.com, with "subscribe gcboaters" as the only line in the message body. To unsubscribe send "unsubscribe gcboaters". For further information send "info gcboaters", or see http://www.songbird.com/gcboaters ====================================================================