Dredging records indicate that 50,785 cu yd of sediment was removed during
the period November 1935 to May 1936. The volume change for the total study
area below mlw is here calculated to be 44,000 cu yd. The volume change for a
selected portion of the Federal navigation channel below mlw, as indicated in
Figure 4-20, was calculated to be 25,500 cu yd. The average pre-dredging depth
for the Federal navigation channel was calculated to be 3.2 ft mlw, and the
average depth after dredging was calculated to be 9 ft, a figure which conforms
to the specified project depth of 7 ft mlw with 2 ft allowable overdraft. The
volume change for what was defined to be the flood shoal proper, as outlined in
Figure 4-19a and 4-19b, was calculated to be 20,100 cu yd. The lobes of the
flood shoal within the Federal navigation channel were removed, as were a
considerable portion of the east lobe outside the channel and a small portion of
the west lobe outside the channel.
Figure 4-20. Federal navigation channel study area
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Chapter 4 Morphology Change, and Channel Shoaling and Migration