River stage fluctuations in the Mississippi and Illinois rivers over time
The Mississippi River and its tributaries are used heavily for shipping, community water resources, and commercial and recreational activities. River stage, or water level, fluctuates naturally over time in rivers but this variability can also be influenced by anthropogenic activity. Understanding trends in hydrologic changes is important for determining how to best use and manage water. This thesis explores river stage as an indicator of variability in the Mississippi and Illinois Rivers to explore if there are trends present over time and along the span of these rivers that could be related to climate, land use, and water use. Daily river stage data was extracted from 22 US Army Corps of Engineers gauges, which were selected along the upper and lower sections of the Mississippi River and one of its tributaries, the Illinois River. The months with the highest and lowest average river stage were evaluated for each gauge. Plots were created of average monthly river stage values as a function of year. A linear trend line was fitted to each graph where the slope value represented the change in average river stage per year. Decreasing river stage trends were found in half of the Illinois River gauges and the three most upstream gauges of the lower section of the Mississippi River. Increasing trends in river stage were seen in half of the Illinois River gauges, all gauges in the upper section of the Mississippi River, and the two downstream gauges in the lower section. River stage fluctuation could be due to a variety of factors including natural variation, climate change, river control structures and practices, urbanization, and precipitation. Awareness of this variation allows communities and businesses to effectively adapt their water management practices to a changing river system.