1. Data, Maps and Risk: How Good is Good?
Tropical Storm Nicole Case Study
Kenneth Ashe, P.E., CFM
North Carolina Floodplain Mapping Program

2. windsor

3. Town of Windsor, Bertie County
20,000 people
Coastal plain
Roanoke & cashie river

4. About 2.5 square miles
Just under 2300 people
Bertie county seat since 1774
Sits on the original 100 acres of the original town

5. Founded in early 1700s
Agricultural history
King Bazemore House dates to 1763
Access to Cashie River and streams
Rich wetlands
Quaint eastern nc charm
Livermoor Park and Mini petting zoo
River Center
Heritage Center

9. Tropical Storm nicole

10. Late September 2010
A deep, stationary trough of low pressure parked over the Ohio and Tennessee valleys west of the Appalachians drew a steady stream of tropical moisture, including the remnants of Tropical Storm Nicole, up the East Coast. The results were heavy rain and flooding from Florida to the coastal Carolinas up into the Chesapeake Bay region and NASA's TRMM satellite captured rainfall from the event. In the U.S., highest rainfall occurred over coastal North Carolina where up to ~20 inches, shown in dark brown) fell. Almost all of eastern N.C. received at least 8 to 10 inches of rain (shown in bright green and yellow). From northern Fla. to central Penn. at least 4 inches (shown in darker blue) of rain fell with several areas in excess of ~6 to 8 inches (shown in dark and bright green, respectively). Locally, upwards of just over 20 inches in parts of N.C. Credit: NASA/SSAI, Hal Pierce `

11. NCC
/O.EXT.KAKQ.FL.W T0000Z T0000Z/
/WNDN7.3.ER T1238Z T0630Z T1800Z.NR/
614 AM EDT FRI OCT
...FLOOD WARNING EXTENDED UNTIL SUNDAY EVENING...THE FLOOD WARNING
CONTINUES FOR
THE CASHIE RIVER NEAR WINDSOR
* UNTIL SUNDAY EVENING...OR UNTIL THE WARNING IS CANCELLED.
* AT 05:16 AM FRIDAY THE STAGE WAS 15.3 FEET
* FLOOD STAGE IS 8.0 FEET
* FORECAST...THE RIVER WILL CONTINUE RISING TO NEAR 15.9 FEET BY THIS
AFTERNOON. THE RIVER WILL FALL BELOW FLOOD STAGE SUNDAY EARLY
AFTERNOON.
* AT 15.0 FEET...ROUTE 13...ROUTE 17...AND HOGGARD MILL ROAD
INNUNDATED.

14. Extent of flooding and floodplain mapping

21. Risk & expected damages

22. IHRM Vision Hazard Data 1. Hazard Identification 4. Communication
2. Vulnerable Systems
Built Environment Data,
Critical Infrastructure,
Socio-Economic Variables
First Floor Elevations
3. Risk Assessment
5. Mitigation
4. Communication

23. Hazard Identification
River Flooding (WSEL & Depth Rasters, 3D TINs)
Gold Level:
10%, 4%, 2%, 1%, 0.2%, annual chance recurrence intervals
1% annual chance future conditions with 10%, 20% and 35% imperviousness build-out scenarios
Percent Annual Chance & 15 and 30 Year Probability Rasters
Silver Level:
10%, 2%, 1%, and 0.2% annual chance recurrence intervals
Bronze Level:

24. Gold Level Flooding Data
This is the 1% annual chance depth raster with the vector delineated floodway.

25. Vulnerability Data Collection
Final Building Footprint Database
5.1 Million Buildings
Completed January 2011
Metadata documenting image source and date
Distributed countywide datasets to all Counties
John

26. Vulnerability Data Collection
FFE Database
FFE Data Collected for:
4 IHRM Counties
19 Coastal Counties
7 Map Maintenance Counties
Total: 150,000 Buildings
RMSE accuracy of 0.3 feet
100YR Flood Elevation = 13 ft.
FFE = 5.2 ft.

27. Field Collection
First Floor Elevation
Foundation Type
Roof Shape
Roof Slope
Number of Stories
Parcel Conflation
Occupancy Type
Building Value
Year Built
Heated Sq Ft
HAZUS Block De-Conflation
Roof Cover Type
Roof Cover Quality
Water Resistance
Roof Deck Attachment
Roof Deck Age
Roof Wall Connection
Roof Frame Type
Hurricane Shutters
Roof Tie Downs
Window Area
Masonry Reinforcing
Joist Spacing
Number of Units

28. HAZUS Model Building Type - HU
Attributes available from Census Block geometry
HAZUS Hurricane Building Scheme
Building Type
Occupancy Type
Number of Stories
Southeast Inland
WOOD
RES1 1
Model Building Types Lookup Table
Model Type Lookup
Description
WSF1
Single Family Homes, 1 Story - Wood
Attributes for Model Building Type
Attribute Field
Highest Percentage
Attribute Value
Roof Shape
95%
Gable 5%
Hip
Secondary Water Resistance
100% No 0%
Yes
Roof Deck Attachment
44%
6"/12"
34%
6"/12"
6/8d 6"/6"
22%
6"/6"
Roof-Wall Connection
63%
Strap
37%
Toe-nail
Shutters
For example, From the block geometry if we knew that a structure was OCCUP RES1, Building Type Wood and 1 story we then go to our secondary Model building type lookup table that would in turn filter into the building characteristics distributions table for tertiary attribute assignments.

34. Town of Windsor HAZUS Estimates TS Nicole
30 Buildings Damaged
Total Damage
Building $3.35 million
Contents $5.57 million
Total $9.18 million
Residential Only Damage
Building $2.3 million
Contents $1.52 Million
Total $3.82 Million

35. IHRM Estimates TS Nicole
97 Damaged Buildings
Building and Contents Damage = $475,706

36. FEMA Assistance HA includes: Flood Damages: Building Damage
Contents Damage
Rental Assistance
Flood Damages:
$566,101
Damage only
63 Buildings
$463,000 - $472,000

37. Comparison TS Nicole Flooding (100-year flood discharge) HAZUS IHRM
Buildings 30
Damage $9,180,00
IHRM
Buildings 97
Damage $476,000
FEMA Payments
Buildings
Damage $463,000 - $566,000

38. IHRM Pilot Study IHRM Pilot County
Edgecombe – 100-year Estimated Direct Damages
HAZUS – ~$100 million
IHRM – ~$12 million

39. Risk MAP Early Demonstration
AAL (structure and structure contents losses )
Nash
HAZUS – $31,095,111
IHRM – $ 2,923,246
Pitt
HAZUS – $15,740,508
IHRM – $ ,706
Scotland
HAZUS – $1,153,890.16
IHRM – $ ,654.31
AAL Based on:
10% Annual Chance (10-yr)
4% Annual Chance (25-yr)
2% Annual Chance (50-yr)
1% Annual Chance (100-yr)
0.2% Annual Chance (500-yr)

40. Notes Not all Assistance is Equal Actual Building Location Matters
Building Elevation Matters
Correct Depth Damage Curve Matters
Database Driven Matters

41. QUESTIONS