Galiano Island Sch I - DPA 7, Steep Slope Hazard Map - OCP Bylaw No. 108

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Moderate Hazard (22.5 - 45 degrees)
High Hazard ( > 45 degrees)
Galiano Island
Official Community Plan
Schedule I
DEVELOPMENT PERMIT AREA 7
STEEP SLOPE HAZARD
Bylaw No. 108, 1995
05001,0001,5002,000250
Meters
1:20,000
Galiano Island
Local Trust Committee
G A L I A N O      I S L A N D
Schedule I
DPA 7 - Slope Hazard
¹
BYLAW AMENDMENTS
Bylaw 223  Oct. 2011
This Galiano Island Steep Slopes Hazard Map has been created using a slope gradient generated from a digital elevation model (DEM).
A DEM is a digital representation of ground surface topography, or topographic relief, built using remote sensing techniques and aerial photography.
There are a number of limitations in utilizing aerial photographs to develop Digital Elevation Models (DEM), which should be noted when considering
the spatial resolution of the mapped hazard areas.  The quality of the DEM may vary according to many conditions:  terrain roughness, sampling
density, grid resolution (or pixel size), interpolation algorithm, vertical resolution and terrain analysis algorithm.  The quality of the air photos and
the scale used may have affected the DEM resolution, as the air photos may not have captured all topographic elements, such as ravines,
localized bluffs, or small scale features.  The Galiano DEM was derived from the air photos flown at a scale of 1:16,000, with 0.5 m vertical
accuracy on open ground surfaces and 30 cm horizontal resolution.   For those areas with extensive forest canopy, the elevation accuracy could
vary as much as half of tree height.  Classified Steep Slopes Hazard areas smaller than 36 square metres have been filtered out of this map,
the resolution of these areas having been deemed insignificant to the potential geological hazard.
The rationale and support for the classification of Steep Slopes Hazard designations is contained in the recommendations of a report prepared
for the Islands Trust by Shane Moore, P. Geo., C. N. Ryzuk and Associates.  Copies of the report (C.N. Ryzuk and Associates, Geological Hazard
Mapping Project, Galiano Island, December 2009) can be obtained by contacting the offices of the Islands Trust.
Supporting Data and Limitations

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