sediment concentration to water discharge ratio along the mississippi (and missouri) river

Sediment Concentration to Water Discharge Ratio Along the

Mississippi (and Missouri) RiverCE 397

Statistics of Water Resources

Yao You

Key Points

•Sediment concentration to water discharge ratio decreases downstream;

•Sediment concentration does not reach the limit of river capacity most of the time.

Sediment Concentration Against Discharge

Anoka, MN

Flow velocity increases

correlation coefficient: 0.6804

The Ratio Compared to Discharge

Anoka, MN

Flow velocity increases

The Ratio Compared to Discharge

St. Louis, MO

Flow velocity increases

Data Source

• Very few sites have both consistent (suspended) sediment concentration and water discharge data;

• Qualified sites have uneven data points (3-20);

• Data comes from different time periods.

Treatment of Data

• Few sites: nothing we can do right now...

• Small number of data points: rank sum+t test

• Time period issue: test for trend.

Results

downstream

Majority Trend: Upstream ≥ Downstream

downstream

≥ ≥

Exception: Upstream < Downstream

downstream

<St.

Louis, MO

Sudden Increase of Sediment Concentration Near St. Louis, MO

St. Louis

Missouri River, major sediment supplier for MS

Mississippi River

Missouri River

Missouri River: Results

St. Louis

•Upstream has much larger concentration to discharge ratio;

Missouri River: Results

St. Louis

•Upstream has much larger concentration to discharge ratio;

•The ratio increases near Sioux, IA and Omaha, NE.

Conclusions

•Sediment concentration to discharge ratio decreases downstream;

•Missouri River contributes a significant amount of sediment into the Mississippi River upstream of St. Louis, MO;

•Rivers are not at their full transport capacity most of the time.

Future Work

•Understand the physics of the observed trends;

•Study more rivers to verify those findings.