The First 10 Metres: Coastal Flooding and Social
Vulnerability of Populations in Nova Scotia
Daniel Bryce,
Government of Nova Scotia
Dr. Patricia Manuel, Dr. Eric Rapaport
Byung Jun Kang
School of Planning, Dalhousie University
Halifax, NS
Esri UC 2015
October 26-27
Halifax, NS
OVERVIEW
PART 1: Project Basics
PART 2: Why use proxy extreme flood elevations?
PART 3: Compiling and mapping social vulnerability
PART 4: Overview of ArcGIS models
PART 5: Findings applications and future
considerations
PART 1
What is the relationship between climate change
projections for coastal flooding and social
vulnerability in Nova Scotia?
Social Vulnerability by
Dissemination Area in
Nova Scotia
high
NS Average
low
PROJECT BASICS
Funded by the NS Department of the Environment
Creation of continuous 1m elevation contours for
the province (ASL to 10m) using the best available
topographic data. (Conducted by the Applied
Geomatics Research Group – AGRG)
Development of zones of extreme flooding in
2100, using elevation contours as proxies for
more detailed information.
PROJECT BASICS
Compiling and mapping Social Vulnerability
Indices (SVIs) for all Nova Scotia Dissemination
Areas.
Mapping residential buildings in the proxy extreme
flood level zones.
Overlay mapping to identify spatial relationships
between social vulnerability, housing and the
proxy extreme flood level zones.
PART 2
Why use proxy extreme flood elevations?
The lack of detailed terrain data is sometimes
used as a reason for not moving ahead with
flood risk mapping and zoning.
Do municipalities need the mapping accuracy
of LiDAR to set policy and by-laws for flood
protection?
Why use proxy extreme flood elevations?
1.The first 10 metres of coastal elevation is known
1.The first 10 metres of coastal elevation is known around
around the world as the low elevation, high risk,
the world as the low elevation, high risk, coastal zone.
coastal zone.
2.The projected extreme flood elevations around Nova
Scotia are up to 5m for the Atlantic and Northumberland
Strait coasts and up to 10m for most of the Fundy coast.
3.Nova Scotia has diverse topographic data with different
levels of accuracy.
4.The proxy zones aid climate change adaptation
planning, especially where high quality terrain elevation
data are not available.
SEA LEVEL RISE AND EXTREME FLOOD ELEVATION
Maximum Storm
CHS
Sea level rise HHWLT
Surge to date
Municipality or Representative (2100) + Error (CGVD 28) measured or
Area
Site
Bar (m)
(m)
(estimated) (m)
Plausible Upper
Water Boundary
Level (CGVD 28)
(m)
Sydney
Sydney
1.58
0.68
0.97 (Saxby Gale 2m)
3.23 (4.26)
Cape Breton West Cheticamp
1.58
0.45
1.38 (Saxby Gale 2m)
3.41 (4.01)
Pictou/Antigonish Pictou
Liverpool
Liverpool
1.53
1.54
1.13
1.26
1.49 (Saxby Gale 2m)
1.63 (Juan)
4.15 (4.69)
4.43
HRM
Guysborough
Lunenburg
Halifax Lunenburg 1.54
Canso Harbour
1.58
Lunenburg
1.54
1.36
1.43
1.66
4.53
4.64
4.83
Yarmouth
Yarmouth
1.54
2.85
Annapolis
Digby
1.53
4.73
Amherst
Joggins
1.53
6.14
Kentville
Hantsport
1.48
8.03
Truro
Burncoat Head
1.53
9.27
1.63 (Juan)
1.63 (Juan)
1.63 (Juan)
1.49 (Ground hog day
storm)
1.49 (Ground hog day
storm)
1.28 (Ground hog day
storm)
1.28 (Ground hog day
storm)
1.28 (Ground hog day
storm)
5.88
7.75
8.95
10.79
12.08
Based on data reported in Richards and Daigle, 2011. HHWLT data adjusted from CD to CGVD28
SEA LEVEL RISE AND EXTREME FLOOD ELEVATION
Maximum Storm
CHS
Sea level rise HHWLT
Surge to date
Municipality or Representative (2100) + Error (CGVD 28) measured or
Area
Site
Bar (m)
(m)
(estimated) (m)
Plausible Upper
Water
Fit with
Boundary Level Proxy
(CGVD 28) (m) Scenario
Sydney
1.58
0.68
0.97 (Saxby Gale 2m)
3.23 (4.26)
5m
1.58
0.45
1.38 (Saxby Gale 2m)
3.41 (4.01)
5m
Maximum
or
1.53 Storm Surge
1.13 to date
1.49 measured
(Saxby Gale 2m)
(estimated)
(m) 1.26
1.54
1.63 (Juan)
4.15 (4.69)
4.43
5m
5m
4.53
4.64
4.83
5m
5m
5m
5.88
5m
7.75
10m
8.95
10m
10.79
10m
12.08
10m
Sydney
Cape Breton West Cheticamp
Pictou/Antigonish Pictou
Liverpool
Liverpool
HRM
Guysborough
Lunenburg
Halifax Lunenburg 1.54
Canso Harbour
1.58
Lunenburg
1.54
1.36
1.43
1.66
Yarmouth
Yarmouth
1.54
2.85
Annapolis
Digby
1.53
4.73
Amherst
Joggins
1.53
6.14
Kentville
Hantsport
1.48
8.03
Truro
Burncoat Head
1.53
9.27
1.63 (Juan)
1.63 (Juan)
1.63 (Juan)
1.49 (Ground hog day
storm)
1.49 (Ground hog day
storm)
1.28 (Ground hog day
storm)
1.28 (Ground hog day
storm)
1.28 (Ground hog day
storm)
Based on data reported in Richards and Daigle, 2011. HHWLT data adjusted from CD to CGVD28
5 AND 10 METRE PROXY EXTREME FLOOD ELEVATIONS
Nova Scotia has diverse topographic data sets
LiDAR, available through
• Atlantic Climate Change Adaptions Solutions
• Applied Geomatics Research Group
• Halifax Regional Municipality
• Cape Breton Regional Municipality
Municipally collected Pictometry - derived data
• Municipal District of Chester (2 m elevations)
• Municipal District of Yarmouth (2 m elevations)
Nova Scotia 1:10,000 Topographic Database (NSTDB)
• NSTDB 20 m DEM
• 5 m contour mapping
Map provided by Applied Geomatics Research Group (AGRG)
Generated static flood inundation levels between
0 and 10 metres CGVD28
– 1 m intervals in LiDAR DEM areas
– 5 m intervals in NTSDB 20 m resampled data areas
Seamless Contours
Map provided by Applied Geomatics
Research Group (AGRG)
COMPARING ELEVATION MAPPING FROM NS DATA SETS
AGRG resampled the NSTDB 20 m DEM to a 2 m DEM
product using a cubic convolution interpolation method.
5 and 10 metre proxy extreme flood zone regions
5m Proxy Region
10m Proxy Region
5 m proxy extreme flood elevation in
2100 Canso, Guysborough County, NS
N
10 m proxy extreme flood elevation in 2100
Truro and parts of Colchester County, NS
N
Extracted from map by Daniel Bryce
Social Vulnerability Index - SVI
PART 3
Social Vulnerability: The inability of
people, individually or as a group, to
Dissemination Area
withstand negative impacts from stresses.
N
The smallest unit for
which Statistics Canada
reports the full set of
population statistics.
DAs are defined by
population – 400 to 700
people.
Social Vulnerability by
Dissemination Area in
Nova Scotia
DAs havehigh
relatively
stable geographic
boundaries,
but vary
NS Average
widely from one another
in spatial extent.
low
Map by Daniel Bryce
NS DAs colour-coded for Social Vulnerability
Statistical data from Statistics Canada 2011 Census and NHS
Social Vulnerability
Social vulnerability arises from inequities of access to social,
cultural and economic resources. These are often what people
need to endure and recover from challenging situations:
• good quality housing
• connections to community supports
• income for repairs, supplies
In addition, some people in society may have more difficulty
accessing necessary resources
• senior adults living alone
• one-parent households
• people with limited income
When a population comprises a larger proportion of socially
vulnerable groups, that population may be socially vulnerable.
Social Vulnerability Index - SVI
SVI is calculated using
statistics that represent
measures of Social
Determinants of Health
- Children
- Seniors
- Seniors living alone
- Lone parent families
- No knowledge of English
or French
- Recent immigrants
- Low income
- Unemployed
- Visible minority
- No secondary education
- Aboriginal identity
Map by Daniel Bryce
• Calculate an index for each SV variable
• Each variable index is the Standard Deviation
(SD) from the NS mean for the variable.
• SVI is the average of the sum of SDs of all
variables
• SVI scaled from high to low in steps of +/-0.5 SD
• Average is -0.5 to +0.5 SD
Dissemination Areas in the Town of Amherst, NS
The DA is the smallest unit
at which Statistics Canada
releases data
The denser the population,
the smaller the spatial
extent of the DA
Green lines represent DA boundaries
List of Municipalities in the 10m
Hazard Zone
Clare
Municipality of Digby
the District of
Hants West
Hants East
Annapolis
Municipality of Colchester
the County of
Cumberland
Kings
Amherst
Annapolis Royal
Bridgetown
Digby
Hantsport
Kentville
Town of
Parrsboro
Stewiacke
Truro
Windsor
Wolfville
How the 10m & 5m
Proxy Zones were
created…
Nova Scotia Dissemination Areas with Social
Vulnerability
Nova Scotia Dissemination Areas with Social
Vulnerability + 10m or 5m Zone Intersect
Nova Scotia Dissemination Areas with Social
Vulnerability + 10m or 5m Zone Intersect + Contain
Dwelling in 10m or 5m Zone
PART 4
Models to Select Out Residential Dwellings
Link Models to Select Out Residential
Remove “non-residential” data based on CORP field (aka “the
Condo Problem”): “Unknown”, Municipal, Provincial, Federal
associated buildings, commercial, some Ltd Companies,
industry, etc.
Calculation of Fields for the Hazard Zone Tables
Count Field – number of residential structures (points) in the
corresponding dissemination block
Ratio Field – The difference between the total dwellings in the
dissemination block from the 2011 census and the number of civic points
in the block that are in the Hazard Zone.
[DBtdwell2011] - [Count_] = Ratio
Risk_Dwell Field – Adjusted number of residential structures in the
corresponding dissemination block. Calculated by entering the number
from the Count Field if the Ratio Field is less than Zero otherwise the total
number of dwellings for the block from the census.
!Count_! if !Ratio! >-1 else !DBtdwell2011!
This adjustment is done because of certain errors that made the number
of dwellings at risk greater than the total dwellings recorded in the census.
Calculation of Fields for the Hazard Zone Tables
Risk_D_Per Field – Percentage of the total dwellings from the
dissemination block in the Hazard Zone.
Risk_D_Per = [Risk_Dwell]/ [DBtdwell2011])*100)+0.5
Risk_Pop Field – Number of people in the Hazard Zone for the
corresponding dissemination block.
[DBpop2011] / [DBtdwell2011]) * [Risk_Dwell]
Risk_PopAd Field – Adjusted number of people in the Hazard Zone for
the corresponding dissemination block.
!Risk_Pop! if !DBpop2011! > !Risk_Pop! else !DBpop2011!
RPop_Pcent Field – Percentage of the total population from the
dissemination block in the Hazard Zone.
RPop_Pcent", "(([Risk_PopAd] / [DBpop2011] )*100)+0.5
Findings The first 10 metres: Coastal flooding and
vulnerability of populations in Nova Scotia
PART 4
Findings Social Vulnerability
1,645 DAs in Nova Scotia
-
Boundaries of 850 DAs fall within the proxy extreme flood level zones
Based on an analysis of 1618 DAs:
-
SVIs are in the NS average social vulnerability range for 41% of DAs
-
SVIs are lower than NS average social vulnerability for 40% of DAs
-
SVIs are higher than NS average social vulnerability for 19% of DAs
For the DAs that border the coast or intersect the proxy flood
elevation zones:
- SVIs are in the NS average social vulnerability range in 47% of DAs.
-
SVIs are lower than NS average social vulnerability in 35% of DAs
-
SVIs are higher than NS average social vulnerability in 18% of DAs
Findings Residential Buildings
19,795 residential buildings are in the proxy
extreme flood elevation zones:
- 16,927 in 416 DAs in the 5 m proxy extreme flood zone
-
Atlantic and Northumberland Strait coasts
- 2,868 in 136 DAs in the 10 m proxy extreme flood zone
-
Fundy coast
There are 298 DAs where there are no residential buildings
located in the projected, proxy extreme elevation zones.
Findings Issues
Issues with DAs in Nova Scotia and Data Quality
• Statistics Canada supressed data in 27 NS DAs. WHY?
– Non-participation in the voluntary National Household Survey
2011 – the source of the social statistics that are part of the SVI.
– These DAs are not included in the analysis even though most
border the coast.
– Twenty of these DAs are aboriginal communities.
Town of Annapolis and Annapolis County
10 m proxy worst-case scenario flooding estimated for 2100
SVI is above NS average
for the town and west of
town and the area is
almost entirely in the proxy
flood zone
SVI is average or lower
than average east and
directly south of town.
SVI is substantially higher
than average to the south
and southeast.
>29 residential buildings in
the town are located in the
proxy flood zone.
Products
Technical Report
File Geodatabase containing
• Contiguous contour layer for the entire coastline of Nova
Scotia (1m intervals to 10 m elevation), useable to a
scale of 1:2000 in some locations
• 5 and 10 m proxy extreme flood zones boundaries
• Dataset of social vulnerability for the province based on
the 2011 Census of Canada and National Household
Survey.
• Dataset of residential building locations in the proxy
extreme water zones.
Opportunities Future Assessments
1. Access to services
2. Emergency access planning
3. Strategic land acquisitions for coastal public access
4. Planning for habitat and ecosystem migration
5. Impacts on municipal assessments, tax base