Sea Level Rise Adaptation Primer - Atlantic Climate Adaptation ...

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Sea Level Rise Adaptation Primer - Atlantic Climate Adaptation ...

SEA LEVEL RISE ADAPTATION PRIMER DRAFT PAGE | 37

The Coastal Floodplain Mapping Guidelines and Specifications report by Kerr Wood Leidel and Associates for the

B.C. Ministry of Forests Lands and Natural Resource Operations outlines four basic steps required to develop

coastal floodplain maps:

1. Acquisition of detailed floodplain topography;

2. Coastal engineering analysis to estimate the water level components associated with the design condition

and the associated Flood Construction Levels;

3. Preparation of floodplain maps indicating areas subject to flood hazard(s) and the magnitude of the

hazard(s); and

4. Preparation of a Design Brief to document the analysis.

The Kerr Wood Leidel report also suggests coastal floodplain maps contain the following elements: FCL's out to

the years 2100 and 2200; floodplain limits to 2100 and 2200; SLR planning areas for 2100 and 2200 and a

tsunami evacuation planning area (if applicable) 38 .

Coastal flood hazards are determined by the interaction of storm surges and waves with seabed bathymetry and

coastal land cover. The mapping of coastal areas at risk of flooding, inundation or susceptible to erosion is a vital

tool for land use planning with respect to SLR. This tool consists of superimposing new SLR levels on a

topographic base map to identify new areas subject to hazards.

The intent of coastal floodplain maps is to locate the position of the future floodplain limits; potential coastal

erosion resulting from the position of the floodplain with respect to the surrounding terrain should be considered

as part of the planning process to establish setbacks 39 .To effectively map the extent of coastal hazards, accurate

topographic data are required, ideally with a contour interval of 1m or less. The traditional method is by surveying

the topography on the ground. However, LIDAR – Light Detection and Ranging, which requires collecting

elevation data from an aircraft using a laser, is increasingly used.

LIDAR offers both an accurate and economical means of topographic mapping, particularly where large surface

areas are involved. The set of elevation points generated by a LIDAR survey can be brought into a geographical

information system (GIS) and used to build surfaces that represent the earth’s topography with great precision.

This provides the ideal base map to determine coastal hazard risk 40 .

Ground surveys provide the highest accuracy; however to cover an entire coastline this way may be impractical

and prohibitively expensive. Ground surveys may be used to supplement or monitor the accuracy of the results

received from LIDAR or other technologies. Further, specific site studies in highly critical areas may benefit from

the increased accuracy that may be achieved through a ground survey.

38 (Kerr Wood Leidal Associates Ltd. 2011)

39 (Kerr Wood Leidal Associates Ltd. 2011)

40 (Birch Hill GeoSolutions 2008)

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