channel variability through time and the pre-cutoff 1930 river pattern. Figure 5.5 shows great
differences in the variability of sinuosity among reaches and for each of the reaches through
time. The differences among the reaches are for the most part the result of tectonic
deformation of the valley floor and the presence of more resistant materials in the bed and or
banks, such as clay plugs, Pleistocene-age alluvium, and Tertiary-age bedrock. A plot of the
valley (floodplain) slope, based upon the 1880 bankfull elevations (Figure 5.7) shows
considerable variability, as a result of these controls. The Mississippi is characterized by a
lack of uniformity in its morphology and dynamics, which has made the job of the river
engineer difficult. The great variability is largely the result of geomorphic and geologic
controls (Schumm et al. 1994).
Figure 5.6. Mississippi River reaches between Cairo, Illinois and Old River, Louisiana (after
Schumm et al. 1994).
Figure 5.7. Mississippi River valley profile (after Schumm et al. 1994).