Lauren Patterson December 6, 2006 Geography 593
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Spatial Relationships between Socio- Spatial Relationships between Socio- economic economic Indicators and Floodplain Maps in North Indicators and Floodplain Maps in North Carolina: Carolina: Are Digital Flood Insurance Rate Maps a Good Are Digital Flood Insurance Rate Maps a Good Answer for Flood Policy? Answer for Flood Policy? Lauren Patterson Lauren Patterson December 6, 2006 December 6, 2006 Geography 593 Geography 593
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Spatial Relationships between Socio-economic Indicators and Floodplain Maps in North Carolina: Are Digital Flood Insurance Rate Maps a Good Answer for Flood Policy?. Lauren Patterson December 6, 2006 Geography 593. 90% of natural disasters in US are floods. - PowerPoint PPT Presentation
Transcript of Lauren Patterson December 6, 2006 Geography 593
Spatial Relationships between Socio-Spatial Relationships between Socio-economiceconomic
Indicators and Floodplain Maps in North Indicators and Floodplain Maps in North Carolina:Carolina:
Are Digital Flood Insurance Rate Maps a Good Are Digital Flood Insurance Rate Maps a Good Answer for Flood Policy?Answer for Flood Policy?
Lauren Patterson Lauren Patterson December 6, 2006December 6, 2006 Geography 593 Geography 593
Overview of Hazards in USOverview of Hazards in US
ECONOMIC COSTS OF HAZARDSECONOMIC COSTS OF HAZARDS
$6 - $10 Billion = all hazards
$2.3 - $4 Billion = floods
90% of natural disasters in US are floods
Shift from rural to urban
Increasing costs through time
U.S. Flood Control PoliciesU.S. Flood Control Policies
Government Policy:1) Structural Control2) National Flood Insurance Program3) Mitigation and Floodplain Zoning 100 year floodplain concept
Hurricane FloydHurricane Floyd Source: Jackson, 2002
Research QuestionsResearch Questions
1) What is the geographic relationship of people and property inside and outside of the 100 and 500 year floodplains?
Specifically, is there a large increase in people and property directly outside the 100 year floodplain boundary, where regulations cease?
2) How do the DFIRM values for the 100 and 500 year floodplain compare with the original FIRM values?
Study Area and Data AvailabilityStudy Area and Data Availability
Study Sites:Study Sites: 1) 1) Wake County: PiedmontWake County: Piedmont 2) 2) Craven County: Coastal PlainsCraven County: Coastal Plains 3) Buncombe County: Mountains3) Buncombe County: Mountains
Selected CountiesSelected Counties
COUNTY NLCD DEM POPULATION PARCEL DFIRMS TOPOGRAPHY
Wake YES YES YES YES YES Piedmont
Buncombe YES YES YES YES NO Mountain
Craven YES YES YES YES YES Coastal
Methodology: Database Methodology: Database ManagementManagement
Methodology: Form 1 – Data PreparationMethodology: Form 1 – Data Preparation
NLCD
DEM
Population Data
Parcel Data
Project to NCState Plane (m)
Mask toCounty
NC Counties Extract County
COUNTY LEVELCOUNTY LEVEL
NLCD, DEM, NLCD, DEM, Population, Population,
ParcelParcel
File = Workspace & "\Projected\" & County & "County.shp" If gp.Exists(File) Then MsgBox "The County file has already been clipped." Else Call ClipCounty(County, Workspace & "\Projected\County.shp", File) End If Dim ClipFile As String ClipFile = File File = Workspace & "\Projected\" & County & "DFIRMS.shp" If gp.Exists(File) Then MsgBox "The DFIRM file has already been clipped." Else Call ClipDFIRMS(Workspace & "\Projected\DFIRMS.shp", File, ClipFile)End If
Methodology: Form 1 – Data PreparationMethodology: Form 1 – Data Preparation
Run a portion of the code as demo
Dim gp As ObjectSet gp = CreateObject("esriGeoprocessing.GPDispatch.1")'Check to see if the file already exists File = Workspace & "\Projected\Pop" & County & "00.shp" If gp.Exists(File) Then MsgBox "The population data has already been projected." Else Call ProjectFeatures(Workspace & “Raw\Population\" + County + "00.shp", File) End If
Methodology: Form 1 – Data Layers Methodology: Form 1 – Data Layers CreatedCreated
DEM NLCD DFIRM
PARCEL 2000 POP FIRM
Methodology: Form 2 – Creating Methodology: Form 2 – Creating Floodplain LayersFloodplain Layers
100 yr
500 yr
Run Code for DFIRMS
Methodology: Form 2 – Creating Methodology: Form 2 – Creating Analysis LayersAnalysis Layers
01Herbaceous Wetlands
01Woody Wetlands
0500CultivatedCrops
0500Pasture/Hay
01Grasslands
01Shrub
0500Mixed Forest
0500Evergreen Forest
0500Deciduous Forest
01Barren Land
2050000High Density Residential
1050000Commercial, Industrial
2050000High Density Developed
75000Low Density Residential
00Water
PopulationBuilding TaxNLCD Type
Process for Reclassifying NLCDProcess for Creating Land Tax SurfaceProcess for Creating Building Tax SurfaceProcess for Creating Total Tax Surface
dRasterParcelBuilNLCD
NLCDdFinParBuil
SumBuild
Build
TaxSurface = FinParLand + FinParBuild
Figure 4A: Tax Surface for Craven County
Methodology: Form 2 – Creating Methodology: Form 2 – Creating Analysis LayersAnalysis Layers
kParcelBlocPixels
RasterParcelLandFinParLand
Methodology: Form 2 – Creating Methodology: Form 2 – Creating Analysis LayersAnalysis Layers
0000 Re PopulationNLCD
NLCDSurfacePop
oupPopBlockGr
classPop
Run Population Code
Methodology: Form 3 - Spatial AnalysisMethodology: Form 3 - Spatial Analysis
500 DFIRM/FIRM
# People Affected
Amt Land Cover Type Affected
Parcel Money Affected
Maximum DEM Height
100 DFIRM/FIRM
# People Affected
Amt Land Cover Type Affected
Parcel Money Affected
Maximum DEM Height
-Socio-Economic
Differences betweenFloodplains
=
NLCD, DEM,
Population Surface,
Tax Surfaces
100 Yr DFIRM100 Yr FIRM
500 Yr DFIRM500 Yr FIRM
Zonal Stats as a Table
100 /500 Yr Flood
# People
% Land Cover Type
Property Value
Methodology: Form 3 - Spatial AnalysisMethodology: Form 3 - Spatial Analysis
Run Code for 1st Button
AgreeFIRM DifferDFIRM Differ
Results: Craven CountyResults: Craven County
Figure 9:
Results: Wake CountyResults: Wake County
Population and Tax Density by Floodplain
0
50
100
150
200
250
300
WAKE TOTAL DFIRM 100 YR DFIRM 500 YR FIRM 100 YR FIRM 500 YR
Po
pu
lati
on
De
ns
ity
(#
/ k
m)
0
5
10
15
20
25
30
Ta
x D
en
sity
($1
,00
0,0
00
/ km
)
Population
Tax
Results: Buncombe CountyResults: Buncombe County
Population and Tax Density by Floodplain
0
200
400
600
800
1000
1200
BUNCOMBE TOTAL FIRM 100 YR FIRM 500 YR
Po
pu
lati
on
De
ns
ity
(#
/ k
m)
0
5
10
15
20
25
30
Ta
x D
en
sity
($1
,00
0,0
00
/ km
)
Population
Tax
TOPOGRAPHIC SIGNATURETOPOGRAPHIC SIGNATURE
N 2000 Pop % N Tax Val % N Area % N Pop Dens % N Tax Dens %
Buncombe FIRM 100 - MOUNT 5.14 3.10 3.57 144 87
Wake FIRM 100 - PIEDMONT 2.47 2.81 9.16 27 31
Craven FIRM 100 - FLOODPLAIN 15.20 19.55 28.53 53 69
Buncombe FIRM 500 - MOUNT 2.20 0.46 0.23 941 197
Wake FIRM 500 - PIEDMONT 0.61 0.63 0.72 85 87
Craven FIRM 500 - FLOODPLAIN 4.03 3.40 1.15 352 297
N 2000 Pop % N Tax Val % N Area % N Pop Dens % N Tax Dense %
Wake DFIRM 100 - PIEDMONT 2.17 2.55 8.80 25 29
Craven DFIRM 100 - FLOODPLAIN 11.76 15.78 22.54 52 70
Wake DFIRM 500 – PIEDMONT 0.49 0.59 1.58 31 37
Craven DFIRM 500 - FLOODPLAIN 4.50 3.22 1.75 258 184
CONCLUSIONSCONCLUSIONS
Increased Development Density outside the 100 yr Floodplain Indicates floodplain boundaries are working? Indicates development directly outside regulation?
Differentiation between different topographies influences floodplain boundaries and the extent of development within those boundaries.
More people and property were protected in FIRMS than in the new DFIRMS
The programming of this process enables rapid analysis of additional counties.
Results: DFIRM Versus FIRM AgreementResults: DFIRM Versus FIRM Agreement
0
50
100
150
200
250
300
350
Po
pu
lati
on
/ k
m
DFIRM & FIRMAgree
DFIRM & FIRMDisagree
DFIRMDisagrees
FIRM Disagrees
Population Density in Floodplains
0
10
20
30
40T
ax
($
1,0
00
,00
0)
/
km
DFIRM & FIRMAgree
DFIRM & FIRMDisagree
DFIRMDisagrees
FIRMDisagrees
Tax Density in Floodplains
0
50
100
150
200
250
Po
pu
latio
n /
km
DFIRM & FIRMAgree
DFIRM & FIRMDisagree
DFIRMDisagrees
FIRMDisagrees
Population Density in Floodplains
0
2
4
6
8
10
12
14
16
Ta
x (
$1
,00
0,0
00
) / k
m
DFIRM & FIRMAgree
DFIRM & FIRMDisagree
DFIRMDisagrees
FIRM Disagrees
Figure 12B: Tax Density in Floodplains
CRAVEN WAKE100 yr floodplain500 yr floodplain
