Extremes on the Mississippi River

Over the last two years, the flow in the Mississippi River has been marked by extremes. In Spring 2011, record water levels forced evacuations while, more recently, drought has threatened shipping routes. After seeing another NYT article covering the impacts that the drought is having on shipping routes last Friday, I decided to take a look at the data in HIS. 

Ideally, I wanted to find a few different sites along the Mississippi and download and compare discharge data over the past couple years. I knew that the USGS NWIS Daily Values, readily accessible in HIS, has national coverage measuring discharge levels daily. So, I went about scrolling down the Mississippi in HydroDesktop looking for NWIS sites to compare. 

HydroDesktop Tip: Use the Select Data Sources tool to limit searches to specific data sources.

I found three such sites where I could compare the discharge values since 2011: St. Louis (MO), Vicksburg (MS), and Belle Chasse (LA). The location of these sites can be seen in Google Earth below...

I found that the discharge time series of all three of these sites displayed a signature of these recent extreme events, but the typical flow, and amplitude of these events, differed by site...

While the St. Louis site is characterized by consistently lower rates of discharge (a maximum of ~600,000 cubic feet per second since January 2010) and less fluctuation, the other two sites have both crossed the 1,000,000 cubic feet per second seasonally. A dramatic increase in flow can definitively be observed in 2011 at the Vicksburg site (corresponding to the aforementioned Spring 2011 record water levels). And, while the flow rate at the Belle Chasse site is more similar to Vicksburg than that of St. Louis, the signal of the extreme events does not display as dramatic fluctuations.

Individual graphs of each of the time series can be seen below...

Observed Discharge of the Mississippi River at St. Louis, MO since January 2011. Note the decrease in 2012 when compared to the previous two years.

Observed Discharge of the Mississippi River at Vicksburg, MS since January 2011. Note the dramatic peak flow in Spring 2011.

Observed Discharge of the Mississippi River at Belle Chasse, LA since January 2011.