Flooding trends In Iowa and across the Midwest Larry Weber Executive - PowerPoint PPT Presentation

A vision for a m ore resilient Iow a A vision for a m ore resilient Iow a T he Iow a Wat ershed Approach T he Iow a Wat ershed Approach Flooding trends In Iowa and across the Midwest Larry Weber Executive Associate Dean College of Engineering The University of Iowa

A vision for a m ore resilient Iow a A vision for a m ore resilient Iow a T he Iow a Wat ershed Approach T he Iow a Wat ershed Approach Trends in floods and heavy rainfall events

A vision for a m ore resilient Iow a A vision for a m ore resilient Iow a T he Iow a Wat ershed Approach T he Iow a Wat ershed Approach Trends show more floods in recent decades

A vision for a m ore resilient Iow a A vision for a m ore resilient Iow a T he Iow a Wat ershed Approach T he Iow a Wat ershed Approach Trends show more frequent floods and heavy rainfall Increased flooding Increased heavy rainfall

A vision for a m ore resilient Iow a A vision for a m ore resilient Iow a T he Iow a Wat ershed Approach T he Iow a Wat ershed Approach (a) (b) (c)

A vision for a m ore resilient Iow a T he Iow a Wat ershed Approach

A vision for a m ore resilient Iow a T he Iow a Wat ershed Approach Q 100 = 26,350 cfs

A vision for a m ore resilient Iow a T he Iow a Wat ershed Approach Q 500 = 35,800 cfs

A vision for a m ore resilient Iow a A vision for a m ore resilient Iow a T he Iow a Wat ershed Approach T he Iow a Wat ershed Approach Historic Crests At Decorah, IA Historic Crests at Dorchester, IA (1) 17.90 ft, 34100 cfs, on 06/ 09/ 2008 (1) 24.30 ft, 38000 cfs, on 08/ 25/ 2016 (2) 15.20 ft, 25640 cfs, on 05/ 29/ 1941 (2) 22.46 ft, 31200 cfs, on 06/ 09/ 2008 (3) 14.35 ft, 20500 cfs, on 08/ 17/ 1993 (3) 22.20 ft, on 02/ 28/ 1948 (ice) (4) 13.68 ft, 19800 cfs, on 08/ 24/ 2016 (4) 21.80 ft, 30400 cfs, on 05/ 30/ 1941 (5) 13.08 ft, 20200 cfs, on 03/ 27/ 1961 (5) 20.89 ft, on 03/ 05/ 1937 (ice) (6) 12.31 ft, 15300 cfs, on 06/ 01/ 2000 (6) 20.02 ft, 25500 cfs, on 06/ 23/ 2013 (7) 12.20 ft, 14754 cfs, on 03/ 17/ 1945 (7) 20.00 ft, 22000 cfs, on 08/ 17/ 1993 More flash flooding occurred in Decorah and Freeport in 2016.

A vision for a m ore resilient Iow a A vision for a m ore resilient Iow a T he Iow a Wat ershed Approach T he Iow a Wat ershed Approach

A vision for a m ore resilient Iow a A vision for a m ore resilient Iow a T he Iow a Wat ershed Approach T he Iow a Wat ershed Approach Freeport 2016 Flood Menards Site (19800 cfs) Wal ‐ Mart drone video by Jewellable Productions

A vision for a m ore resilient Iow a A vision for a m ore resilient Iow a T he Iow a Wat ershed Approach T he Iow a Wat ershed Approach 2016 Flood (19800 cfs) Freeport drone video by Jewellable Productions

A vision for a m ore resilient Iow a A vision for a m ore resilient Iow a T he Iow a Wat ershed Approach T he Iow a Wat ershed Approach 1D Model of Upper Iowa River created by USGS in 2010 used to develop Preliminary FEMA Study

A vision for a m ore resilient Iow a T he Iow a Wat ershed Approach What is a Floodway?

LiDAR Terrain Data A vision for a m ore resilient Iow a T he Iow a Wat ershed Approach

1D Model created by USGS in 2010 Used to create the Preliminary FEMA Study A vision for a m ore resilient Iow a T he Iow a Wat ershed Approach

2008 Flood (33800 cfs) High Water Marks Compared to Simulation Obs = 841.6 A vision for a m ore resilient Iow a Obs = 843.1 T he Iow a Wat ershed Approach Sim = 841.6 Sim = 842.5 Obs = 840.7 Obs = 844.4 Sim = 841.2 Sim = 844.0 Obs = 845.9 Sim = 846.5 Obs = 849.5 Obs = 850.1 Sim = 849.5 Sim = 849.2

Addition of Proposed Menards A vision for a m ore resilient Iow a T he Iow a Wat ershed Approach Pond Depth = 10ft Menards Assuming the Menards detention pond is at permanent pool, the fill added to floodplain is approximately 1.7 million cubic feet. At the peak of the 2008 Flood, this volume would have filled in 1 minute.

Removal of Existing Wal ‐ Mart site A vision for a m ore resilient Iow a T he Iow a Wat ershed Approach Removal of Wal ‐ Mart Site

A vision for a m ore resilient Iow a T he Iow a Wat ershed Approach

A vision for a m ore resilient Iow a T he Iow a Wat ershed Approach

A vision for a m ore resilient Iow a T he Iow a Wat ershed Approach

A vision for a m ore resilient Iow a T he Iow a Wat ershed Approach

A vision for a m ore resilient Iow a T he Iow a Wat ershed Approach

A vision for a m ore resilient Iow a T he Iow a Wat ershed Approach

A vision for a m ore resilient Iow a T he Iow a Wat ershed Approach Iowa Flood Center The University of Iowa 100 C. Maxwell Stanley Hydraulics Laboratory Iowa City, IA 52242 319-384-1729 www.iowafloodcenter.org 26