SJRA Peak Flow Map from Imelda Shows 1500X Difference Between East/West Sides of Watershed

Here’s a science lesson for the entire family. The SJRA’s peak streamflow and rainfall map for Imelda demonstrated how rain can fall heavily over one part of a watershed and barely touch another. There are huge implications for flooding.

Peak Streamflows West to East Vary by 1500X

Note how the gage at Spring Creek in Tomball recorded a peak flow of 22.7 cubic feet per second. The East Fork gage in New Caney registered 34,600 cubic feet per second. That’s a difference of more than 1500X in the peak flow rates!

Rainfall Totals Range from 0 to 30 Inches in 24 miles

The blue figures represent precipitation. That same gage in Tomball recorded none. But a little further east, they picked up more than 5 inches; almost 10 at I-45; more than 15 at I-69, and almost 30 in New Caney.

This is why you need to look at gages upstream on YOUR tributary when flooding is possible! Someday, textbooks will use this map to dramatize that lesson.

Posted by Bob Rehak on 11/5/2019

798 days since Hurricane Harvey and 47 since Imelda