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Physics and Engineering: Flooding Event Comparison

April 18, 2013, 11:08 am: Wow, another big storm and flooding event! I thought it would be interesting to do a quick comparison between the September 2008 flooding event and the current one. For those who don't remember the September 2008 event, you can learn more about it from the North Park news archives here and here.

I thought folks might find a comparison between the current flood and the 2008 flood to be interesting. In September 2008, here was the gage height of the North Branch of the Chicago River at Albany Avenue (just by the North Park football field) as measured by the USGS:


The peak height was just shy of 8.0 ft. Here is the current graph of gage height (as of April 18, 2013, 9 am):


The peak thus far is something around 8.5 ft. For the current instantaneous data from the Albany Avenue gaging station, go here.

And here is the record of rainfall measured at the Helwig Weather Station, as of 10 am, April 18, 2013 (I don't have the 2008 plot):


Some statistics about rainfall measured at the Helwig Weather Station for the 2013 storm (as of 10:41 am):

  • Storm Total: 3.78 in (since April 17, 2013, 10:30 am)
  • High Rain Rate: 5.88 in/hr at April 18, 2013, 7:39 am

So, what does this all mean? To state the obvious, we got a lot of rain and the river is running really high, comparable to the 2008 event. (Of course, flood stage is, usually, only secondarily the result of local rainfall; what really matters is the amount of rain in the watershed that drains upstream from where you're located.) Sometimes science is counterintuitive but other times science states the obvious; this is one of those latter times :). But, in the case of the obvious, science provides a measure of the nature of the obvious.

Sources: Both graphs of gage height are provided by the USGS (2008, current). The graph of rainfall was generated from Helwig Weather Station data.

Revision at April 18, 2013, 8:00 pm: Minor edits and clarification about the role of local rainfall in flooding.

Revision at April 19, 2013, 11:54 am: Minor edits.

Updated: Friday, 19-Apr-2013 09:55:19 PDT. Disclaimer. Valid CSS, HTML. Author: Johnny Lin, with portions generated by the program wview 5.20.1 (written by Mark Teel and co-authors). The weather graphics on this page are licensed under the GNU General Public License.