Iowa FloodingMark Hughes

November 25, 2008

University of Iowa News Service

Background

• Two “500 year” events• Major damage to the University of Iowa and

surrounding area

University of Iowa News Service

Where In Iowa?

Iowa State University GIS Facility

Flood Elevations

• Iowa River USGS Gauging Station at Iowa City, IA

– 1993 Maximum Elevation = 645.17 ft NGVD 29– 2008 Maximum Elevation = 648.29 ft NGVD 29

11/14

1/3

2/22

4/12

6/1

7/21

9/9

615

620

625

630

635

640

645

650

655

Water Surface Elevations at Iowa City

2008 Elevation 1993 Elevation

Wat

er S

urfa

ce E

leva

tion

(ft)

Calculated Flooding Map

• Map Area Flooded in 1993 and 2008

How accurate is this map?

• Trying to get actual flood data map from the University of Iowa

• Dam before gauging station

Compare To Flood Maps

Map Based on Water Elevation at Iowa City

Actual Iowa City Flood Map

The National Center for Airborne Laser Mapping

NCALM Mapped

2008 Precipitation and Pool Elevation

3/1

3/21

4/10

4/30

5/20

6/9

6/29

7/19

0

10

20

30

40

50

60

70

80

90

660

670

680

690

700

710

720Precipitation and Pool Elevation in 2008

Precipitation Pool Elevation

Prec

ipita

tion

(mm

/hr)

Pool

Ele

vatio

n (ft

)

Spill Way Height

Pool Elevation and Discharge

1/3

2/22

4/12

6/1

7/21

9/9

10/29

660

670

680

690

700

710

720

0

2000

4000

6000

8000

10000

12000

Pool Elevation and Discharge

Pool Elevation Discharge

Pool

Ele

vatio

n (ft

)

Disc

harg

e (c

fs)

To Do

• Get real flood data• Calculate volumes of storage and discharge• Further look into dam operation requirements

Questions ??