http://web.archive.org/web/20080113220455/http://www.bh.com/companions/0340740671/exercises/prob2.htm
exploration of ancient Egyptian massive flood mitigation
projects , far more advanced than I imagined , seems rain and river
flows have been slowly decreasing over the last 5000 years , possibly
a lot longer , seems this project near Cairo [ was similar to the one
near Abydos ? ], both flowing the '' flood peaks '' off into the
western deserts about 5000 years ago when Abydos boats were being
built .