Flood Risk and Vulnerability Analysis Project - Atlantic Climate ...

3.1 C1 – Compile GIS Base Maps
For each of the communities and areas identified in Table 3-1, a base map was created from
the best available source data. Where available the 1:2500 scale structured digital community
map layers available from the Department of Environment and Conservation Surveys and
Mapping division was used. Where 1:2500 scale structured vector data was not available, the
1:50,000 scale National Topographic Series (NTS) mapping, the best available alternate
dataset, was used. Key layers making up the base maps include: roads, buildings, waterbodies,
wetlands, rivers, contour lines, and other built structures. Satellite imagery collected for this
project was used as a backdrop for the map.
Note: Structured data refers to Shapefiles that were received from the Provincial Government in
which attribution on the individual geometry records within the Shapefiles have been captured.
Unstructured Shapefiles represent records with no attribution making it virtually impossible to
ascertain the details on the geometry feature in question.
3.1.1 Digitization of Flood Plain Data
The primary operational layer to be added to each GIS base map was the flood risk map data
obtained from WRMD (via website download in most cases); specifically the 1:20 and 1:100
year flood lines.
As noted above, some of these needed to be digitized by AMEC GIS staff and converted to a
format compatible with ArcGIS.
Flood lines for 11 communities were digitized from PDF or JPG drawings downloaded from the
Departments website. In many cases these drawings did not line up with the base map and as
such AMEC approximated to positioning of the flood lines.
Bishops Falls Deer Lake Trout River
Brigus Glenwood / Appleton Placentia
Carbonear Glovertown Rushy Pond
Codroy Valley
Steady Brook
Table 3-2. Communities for which Flood Mapping required digitizing from
PDF or JPG drawings
Flood lines for 2 communites where captured from Shapefiles posted on the WRMD website.
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