Flood Map Modernization and North Dakota
Julie Prescott, ND Map Modernization Coordinator
North Dakota State Water Commission
And
Brian Fischer, CFM, GIS Project Manager
Houston Engineering, Inc.
FLOOD MAP MODERNIZATION
Flood Map Modernizatio
nFlood Map Modernization
Nationwide, 5-year, $1 billion program to update FEMA’s Flood Insurance Rate Maps (FIRMs)
Used by local officials in managing development and land use planning, and also in disaster and emergency response planning
Used by lenders and agents in determining the proper protection level for their clients
Flood Map Modernizatio
nFlood Map Modernization
100,000 existing panels nationwide will be modernized to a digital format, publicly available through the Internet
Will allow for timely updates to maps as flood risks change
Local engineering firms are contracted to do the mapping and determine the risk zones
Flood Map Modernizatio
nFlood Map Modernization
Currently, the State of North Dakota has contracted with engineering firms to modernize maps in 11 counties:
Barnes Pembina Walsh
Benson Ramsey
Grand Forks Ransom
Mercer Richland
Nelson Traill
Flood Map Modernizatio
nAcronyms
FIRM – Flood Insurance Rate Map• Official map of a community on which FEMA has
delineated both the special flood hazard areas and the risk zones applicable to the community
DFIRM – Digital Flood Insurance Rate Map• Database that contains all information needed to
produce FIRM maps
FIS – Flood Insurance Study• A flood study to determine the flood hazards, and if
appropriate, the corresponding water surface elevations
Flood Map Modernizatio
nFIRMs to DFIRMs
FIRMs (Old paper maps)• Very outdated
• Difficult to update
• Typically no digital data
• Tough to use with GIS
DFIRMs (New digital data and maps)• Updates maps with new data
• County-wide format
• Digital data is available in a standard database
Flood Map Modernizatio
nFlood Map Modernization
Why is FEMA’s Map Mod Initiative Important to GIS Professionals?
• Lets you incorporate your GIS basemap data
• Produces a product that is better than we had previously
• A lot of us are asked to make decisions and maps for floodplain management
• Gives local communities the opportunity to review the GIS products
Flood Map Modernizatio
nLifecycle of a DFIRM Project
24-36 months
Source: FEMA
Flood Map Modernizatio
nLifecycle of a DFIRM Project
Source: FEMA
Flood Map Modernizatio
nLifecycle of a DFIRM Project
Generally 2 routes for a DFIRM project 1.) Digital Conversion
• Shorter project
• Less Costly
• Used where no needs are identified
2.) New Flood Study• Longer project
• More Expensive
• Generally improves flood hazard data
Flood Map Modernizatio
nLifecycle of a DFIRM Project
GIS is Used Throughout the Project• Basemap Acquisition• Survey and Topographic Data (Flood
Study)• Hydrology (Flood Study)• Hydraulics (Flood Study)• Mapping (Flood Study)• Preliminary DFIRM Database• Preliminary Maps
Flood Map Modernizatio
nLifecycle of a DFIRM Project
Basemap Acquistion• Local data preferred
• Determines vector or raster based panels
• FEMA Guidelines and Standards
S_Perm_Bmk (NGS Benchmarks) S_PLSS_Ar / S_PLSS_Ln (Range, Township, Section) S_Pol_Ar / S_Pol_Ln (Corporate Limits) S_Trnsport_Ln (Transportation – roads, railroads, airports) S_Wtr_Ln / S_Wtr_Ar (Hydro features) S_Quad_Index (USGS Quads) S_Base_Index (DOQs or other imagery)
Flood Map Modernizatio
nLifecycle of a DFIRM Project
Survey and Topographic Data• Structures and channel cross sections
• LIDAR
• Delivered to FEMA in data capture standards database (essentially a geodatabase)
Flood Map Modernizatio
nLifecycle of a DFIRM Project
Flood Map Modernizatio
nLifecycle of a DFIRM Project
Hydrology• Prediction of flows in different rainfall events
• Many methods to calculate flows
• Use GIS to calculate parameters for model
• Uses watershed boundaries, landuse and soils
• Flows are used in Hydraulic Model
100yr event = 100cfs
Flood Map Modernizatio
nLifecycle of a DFIRM Project
Hydraulics• Determines water surface
elevations at each cross section
• Elevations used to mapped floodplain on topographic data
• Detailed studies, limited detailed studies and approximate studies
• Typically utilize HEC-GeoRAS
0 200 400 600 800 10003098
3100
3102
3104
3106
3108
3110
3112
Box Elder Flood Plain 2-6-2006 Plan: Box Elder 100-year 2/7/2006 RS = 15.5 BR Elk Vale Road Bridge
Station (ft)
Ele
vation (
ft)
Legend
WS 100-year (1% ch
Crit 100-year (1% ch
Ground
Ineff
Bank Sta
.063 .05 .063
Cross Section View in HEC-RAS
Flood Map Modernizatio
nLifecycle of a DFIRM Project
Mapping the Floodplain• Partially automated with GIS• Ground surface TIN – Water Surface TIN =
Flood Depth GRID• Conversion of all profiles and BFEs from NGVD
29 to NAVD 88 Datum• Map 1% (100yr) and 0.2% (500yr) chance flood• Determine Floodway, if applicable
Flood Map Modernizatio
nFlood Depth GRID
Flood Map Modernizatio
nWork Map
8.4
8.42 8.43
7.76
7.54
7.18
6.86
6.66 6.64
4TH
ST
N
2ND
ST
N
BR
OA
DW
AY
3RD
ST
N
OA
K S
T
9TH AVE N
1ST
ST
N
6TH AVE N
7TH AVE N
11TH AVE N
1ST AVE N
10TH AVE N
5TH
ST
N
4TH AVE N
NP AVE
8TH AVE N
3RD AVE N
SOUTH TERRACE
2ND AVE N
MA
PLE
ST
NORTH TERRACE
EL
M S
T
AS
H S
T
MILLS AVE
NO
RT
H R
IVE
R R
D
LOWER TERRACE
1ST
ST
N
5TH
ST
N
5TH
ST
N
3RD
ST
N
5TH
ST
N
EL
M S
T
5TH
ST
N
OA
K S
T
3RD
ST
N Legend
Cross Sections
Fargo-Streets
River-CL
Flood-Plain
Flood Map Modernizatio
nLifecycle of a DFIRM Project
Draft work map for Buffalo River FIS
Flood Map Modernizatio
nGIS Uses in Flood Study
Hydrologic Parameters HEC-RAS Geometry
8.4
8.42 8.43
7.76
7.54
7.18
6.86
6.66 6.64
4TH
ST
N
2ND
ST
N
BR
OA
DW
AY
3RD
ST
N
OA
K S
T
9TH AVE N
1ST
ST
N
6TH AVE N
7TH AVE N
11TH AVE N
1ST AVE N
10TH AVE N
5TH
ST
N
4TH AVE N
NP AVE
8TH AVE N
3RD AVE N
SOUTH TERRACE
2ND AVE N
MA
PLE
ST
NORTH TERRACE
ELM
ST
AS
H S
T
MILLS AVE
NO
RT
H R
IVE
R R
D
LOWER TERRACE
1ST
ST
N
5TH
ST
N
5TH
ST
N
3RD
ST
N
5TH
ST
N
ELM
ST
5TH
ST
N
OA
K S
T
3RD
ST
N Legend
Cross Sections
Fargo-Streets
River-CL
Flood-Plain
Automated Floodplain Delineation
Flood Map Modernizatio
nLifecycle of a DFIRM Project
DFIRM Database• Stores all GIS data to produce
map panels• Explained in Appendix L of FEMA
specs• Must adhere to FEMA guidelines
and specs• Undergoes extensive QA/QC
www.fema.gov/pdf/fhm/frm_gsal.pdf
Flood Map Modernizatio
nLifecycle of a DFIRM Project
FEMA DFIRM Tools – Digitizing Flood Hazard Data from Effective FIRM panels
Flood Map Modernizatio
nLifecycle of a DFIRM Project
Map Production (DFIRM Panels)• Must adhere to Appendix K guidelines and specs
• Undergoes extensive QA/QC
Flood Map Modernizatio
nHow do you use a DFIRM?
Paper maps are still printed PDFs of maps DFIRM database (GIS digital data) FEMA Map Service Center (
http://www.msc.fema.gov) FEMA Mapping Information Platform (
https://hazards.fema.gov/wps/portal )
Flood Map Modernizatio
nBarnes County, ND DFIRM
FIS Report• Engineers Report
• FIS Profiles
• Floodway Data Table
Barnes County, ND FIS Profile Sheet
Flood Map Modernizatio
nBarnes County, ND DFIRM
DFIRM Database and GIS Data
Flood Map Modernizatio
nBarnes County, ND DFIRM
Flood Map Modernizatio
nBarnes County, ND DFIRM
DFIRM Panels
Flood Map Modernizatio
n
Questions?
Thank you for Attending!
Julie Prescott, ND Map Modernization Coordinator
North Dakota State Water Commission
And
Brian Fischer, CFM, GIS Project Manager
Houston Engineering, Inc.
FLOOD MAP MODERNIZATION