|
|
- Info
Hydrologic trends in the upper Mississippi River basin
| Author: |
Knapp, H.Vernon |
| Date: |
1994 |
| Periodical: |
Water International |
| Abstract: |
The Upper Mississippi River Basin has experienced considerable hydrologic change in the last two centuries as a result of removal of wetland areas, deforestation and subsequent reforestation, changes in agricultural practices, urbanization, navigation projects, and the construction of levees. It is popularly accepted that the human-induced modifications to the river and its watersheds have increased the amount of flow in the Mississippi River, particularly during flooding events. Long-term stream gage records in the Upper Mississippi River Basin were analyzed to determine trends in stream flows and flooding. Over the 130 years of gaging there have been various periods in which the frequency and magnitude of floods have fluctuated. Trends in average flow and flooding are strongly correlated to coincident increases in average annual precipitation. For many portions of the watershed, precipitation and stream flows over the last three decades have been higher than any earlier period on record. Outside of the dominant influence of climate variation, only one major change on Mississippi River flood discharges is observed. Flood control reservoirs in the Missouri River watershed appear to produce a 10 per cent reduction in the average flood peak and average flood volume for the Mississippi River at St. Louis, Missouri. |
|
