Movement of river traffic such as tows, barges, or recreational
craft in navigable rivers and streams can temporarily alter the
hydraulic characteristics of the river cross section. These
changes may include bow, stern, or transverse waves; resuspension
of bed sediments; changes in velocity structures either in close
proximity to the moving vessel or within the water body; altered
flow direction; and transport of sediment and water into side
channels, sloughs, or backwater lakes. Research is being
conducted at the Illinois State Water Survey to determine and
evaluate the changes that may accompany the movement of river
traffic within the Upper Mississippi River System (UMRS). The
UMRS extends from Cairo, Illinois, at the junction of the
Mississippi River with the Ohio River, to the headwaters of the
Mississippi River in Minnesota. The major tributary of this
system is the Illinois River. Data were collected on waves,
drawdown, sediment, and velocities by using state-of-the-art
equipment and instrumentation. Analysis of the data has shown
that barge traffic can temporarily increase the concentrations of
suspended sediments; that it will alter the two components of the
velocities, the magnitudes of which are dependent upon the
relative distances of the measuring points; and that it can
generate waves and drawdown. The duration of the increases in
suspended sediment concentrations and velocities is dependent on
the traffic characteristics and ambient flow conditions of the
river. It was also observed that flows near the shore zone can
change direction as a result of the movement of loaded or
unloaded barges. Physical changes associated with the river
traffic may alter some biological habitats. Research on physical
changes resulting from river traffic is geared toward determining
the relative importance of alterations in the river environment
and how they may affect the aquatic habitats.
