This is a case study on 2008 Iowa River flood utilizing HAZUS to define strategies on how to mitigate disaster issues on future events.

1. 2008 IOWA RIVER flood:
A CASE STUDY
Andrew Hamer  Andreza Dantas  Devin Burgett
Hazards & Society  Spring, 2015

2. Image from: http://thestudio.uiowa.edu/historycorps/files/original/b1c13003885ed3e073ecb2c546a64f38.jpg
PARKVIEW TERRACE
JUNE, 2008
Also know as Mosquito Flats
One of the most affected areas in Iowa City

3. STORY
One friend
Image from: http://homepage.cs.uiowa.edu/~jones/flood08/
2008 flood
Complete loss
Moved away

4. IN THE PAST, WETLANDS…
Image from: http://thestudio.uiowa.edu/historycorps/files/original/e0f888cfce30c471caf518dcddcea80d.jpg

5. Image from: http://thestudio.uiowa.edu/historycorps/files/original/9d93a29fac1d824f20304e7ecbed3f72.jpg
Residential development
Built in the 1960s
Quiet area
Scenic view

6. Imagefrom:http://gis.johnson-county.com/piv/(2008Flood)
Most of the area was flooded
TERRACE PARKVIEW: 2008 FLOOD

7. Imagefrom:http://gis.johnson-county.com/piv/(2006)
140 properties
TERRACE PARKVIEW: BEFORE

8. Imagefrom:http://gis.johnson-county.com/piv/(2014Aerial)
88 properties purchased (Buyout Program) and only 52 properties remaining
TERRACE PARKVIEW: TODAY

9. FLOODING IS A “VERY
OLD” PROBLEM IN
Parkview terrace

10. FLOODS ARE BEcOMING MORE FREquENT…
… AND MORE
damaging
1993 flood: $4.5 billion
2008 flood: $10.9 billion
Source: Graph (USGS paper, page 25) http://pubs.usgs.gov/pp/1775/pdf/pp1775.pdf
Damage data from NOAA Flood Safety: http://www.floodsafety.noaa.gov/states/ia-flood.shtml (values in in 2013 inflation-adjusted dollars)
According to NOAA, estimated
damage for:

11. HAZUS: THE STUDY REGION AND DATA
Study Region: Iowa > Johnson County >
1 Census Tract and 3 Census Blocks*
*Census Tract: 19103002300, Census Blocks:191030023001000,191030023001001, 191030023001002
** Buyout map updated as of July, 2012: http://www.icgov.org/site/CMSv2/file/buyout/buyoutMap.pdf
DEM Level 1: 1-arc sec USGS (Level 1 scenarios)
Buildings Level 2: User Defined Facilities (UDFs)
DEM Level 2: 1/3-arc sec USGS (Level 2 scenarios)
Buildings Level 1: General Building Stock data
 Updated database using the last Buyout Map** (as of July, 2012)
 Query to select only Parkview Terrace properties
 Imported entries for 51 properties to User Defined Facilities (all of them RES1 type)

12. DATA USED FOR BUYOUT PROGRAM
 Voluntary flood buyout
1 Source: Information extracted from the map depicted in this slide and also available at http://www.icgov.org/site/CMSv2/file/buyout/buyoutMap.pdf
 Funds came from HMGP and CDBG
Results of the Buyout Program (as of July, 2012)1
# of properties % of properties
Purchased 88 63%
Stayed 52 37%
Total 140 100%
 Standard program offered 112% of
the pre-flood value of the home
HMPG: Hazard Mitigation Grant Program and CDBG: Community Development Block Grant Program

13. SUMMARY: SCENARIOS
Level 1 Level 1 Level 2 Level 2 Worst Case
DEM 1-arc sec 1-arc sec 1/3-arc sec 1/3-arc sec 1-arc sec
Inventory GBS GBS Point-data Point-data GBS
Return Period 500-year flood 500-year flood 500-year flood 500-year flood 1,000-year flood
Depth-damage
function
Default (FIA) Default (FIA) Default (FIA) Default (FIA) USACE (IWR/St.Paul)
Levee? No Yes, 500 No Yes, 500 No
Study Region 1 Study Region 2 Study Region 3

14. SUMMARY: RESULTS
Level 1 Level 1 Level 2 Level 2 Worst Case
Total buildings 56 12 56 20 51
Undamaged 1 0 1 3 1
Damaged 55 12 55 17 50
Subst. damaged 24 8 24 10 25
Partially damaged 31 4 31 7 25
Ec. losses (million) $12.27 $3.53 $12.27 $4.33 $13.59
Study Region 1 Study Region 2 Study Region 3

15. SUMMARY: RESULTS
Level 1 Level 1 Level 2 Level 2 Worst Case
Total buildings 56 12 56 20 51
Undamaged 1 0 1 3 1
Damaged 55 12 55 17 50
Subst. damaged 24 8 24 10 25
Partially damaged 31 4 31 7 25
Ec. losses (million) $12.27 $3.53 $12.27 $4.33 $13.59
Study Region 1 Study Region 2 Study Region 3
Same results for Level 1 and 2!!!
Level 2: DB has only 51
buildings! HAZUS didn’t
update DB.

16. SCENARIO 1: LEVEL 1 [MAP]

17. SCENARIO 2: LEVEL 1 + LEVEE [MAP]

18. SCENARIO 3: LEVEL 2 [MAP]

19. SCENARIO 4: LEVEL 2 + LEVEE [MAP]

20. SCENARIO 5: WORST CASE [MAP]

21. WHAT ARE THE Possible mitigation
alternatives?

22. Possible Mitigation Strategies
 Eminent domain buyout
 Offer voluntary buyout to the remaining homeowners and eliminate future development
 Flood berm and drain gates (or a levee)
 Elevate homes
 Lower water level of Coralville Reservoir

23. Possible Mitigation Strategies
Cost/Home Total Cost Advantages Disadvantages
Eminent domain (130%
value pre-flood*)
$168,000 $8.7MM
-One time cost
-Eliminates the problem
-Not socially well accepted
-Reduces tax base
Flood wall/Levee (5,000ft,
500-year flood)
$250,000 $13.0M+**
-Protection to the remaining
homes
-Acquisition of homes
-More “social” disruption in the
community
-Annual maintenance
- Highest cost/home
Elevate homes (500-year
flood)
$29,000 $1.5M
-No maintenance cost
-No homes
acquired/displaced
-Maintains tax base
-Still subject to damage/isolation
-Affects accessibility
Offer voluntary buyout and
eliminate future
development (112% value
pre-flood*)
$134,400 $7.0M
-One time cost
-Reduces base for flood
-May be eligible by HMGP
-Depends on the homeowners
willingness
-Reduces tax base
*Average value pre-flood per home utilized $120,000
**Values obtained from an estimation requested by the City of Iowa City in January, 2009. Available at: http://www.luminpdf.com/files/1191633/Stanley_Consultants_Estimation_Cost.pdf

24. Community feedback

25. OUR Recommendation

26. OUR Strategy
Offer voluntary buyouts (pre-flood)
Prohibit future development

27. Questions?

28. Thank YOU!

29. Image from: http://www.colorado.edu/hazards/o/archives/1999/may99/may99a.html