Flood Mapping Reports

The Somass Watershed Flood Management Plan provides a foundation for future watershed mitigation and adaptation planning.

Final Report

The Final Report summarizes the methodology used in developing the flood maps and provides a condensed overview of the Technical Appendices available below.

FINAL REPORT 2020 (PDF | 3 MB)

Suggested Citation: Northwest Hydraulic Consultants Ltd. (2020): Somass Watershed Flood Management Plan. Prepared for the Alberni-Clayoquot Regional District.

Report Appendices

• Appendix A SURVEYS (PDF | 1 MB)
• Appendix B HYDROLOGY (PDF | 5 MB)
• Appendix C COASTAL ASSESSMENT (PDF | 4.5 MB)
• Appendix D GEOMORPHOLOGY (PDF | 11 MB)
• Appendix E HYDRAULIC MODELLING (PDF | 18.5 MB)
• Appendix F MAPPING METHODOLOGY (PDF | 3 MB)
• Appendix G FLOOD MITIGATION (PDF | 2 MB)
• Appendix H CONSULTATION (PDF | 4 MB)
• Appendix I FLOOD DEPTH MAPS (See below for map set)
• Appendix J DESIGNATED FLOOD MAPS (See below for map set)

Appendix I Flood Depth Maps

The Flood Depth Maps provide a scientifically based estimate of potential flooding in four different coastal climate change conditions: present day (2019), year 2050, 2100, & 2200). These maps will be used for general consideration in high-level planning initiatives and do not inform Floodplain Bylaws.

Please refer to the Final Report above for more in depth description and explanation on these maps.

(NOTE: These maps are very large file sizes and may be slow to download)

• APPENDIX I FLOOD DEPTH MAPS - PRESENT DAY (PDF | 80 MB)
• APPENDIX I FLOOD DEPTH MAPS - 2050 (PDF | 80 MB)
• APPENDIX I FLOOD DEPTH MAPS - 2100 (PDF | 80 MB)
• APPENDIX I FLOOD DEPTH MAPS - 2200 (PDF | 80 MB)

Appendix J Designated Flood Maps

The ACRD's new Designated Flood Maps depict minimum flood construction levels based on a 200-year flood event - the Provincial standard for floodplain mapping. Having incorporated expected sea level rise and geomorphic uplift projected for the year 2100, as well as freeboard and wave effects at the shoreline, ACRD residents, property owners, and municipal staff can now determine which areas are most likely to flood and at what elevation building and development is at higher risk. Designated Flood Maps provide the basis for future legislated Floodplain Bylaws. These maps will help inform where and what kind of mitigation efforts are needed, whether it's building above a site-specific elevation (determined through qualified engineers) or constructing retaining walls and improving dikes.

Please refer to the Final Report above for more in depth description and explanation on these maps.

Click the Map Index image below to determine which Map Sheets to download

Map Index

• Appendix J DESIGNATED FLOOD MAPS - INDEX (PDF | 4 MB)
  (The Map Index includes diagrams for interpreting Flood Construction Levels at lake and coastal shorelines)
• Appendix J DESIGNATED FLOOD MAPS - SHEET 1 (PDF | 22 MB)
• Appendix J DESIGNATED FLOOD MAPS - SHEET 2 (PDF | 20 MB)
• Appendix J DESIGNATED FLOOD MAPS - SHEET 3 (PDF | 11 MB)
• Appendix J DESIGNATED FLOOD MAPS - SHEET 4(PDF | 13 MB)
• Appendix J DESIGNATED FLOOD MAPS - SHEET 5 (PDF | 22 MB)
• Appendix J DESIGNATED FLOOD MAPS - SHEET 6 (PDF | 19 MB)
• Appendix J DESIGNATED FLOOD MAPS - SHEET 7 (PDF | 11.5 MB)
• Appendix J DESIGNATED FLOOD MAPS - SHEET 8 (PDF | 18 MB)
• Appendix J DESIGNATED FLOOD MAPS - SHEET 9 (PDF | 23 MB)
• Appendix J DESIGNATED FLOOD MAPS - SHEET 10 (PDF | 14 MB)
• Appendix J DESIGNATED FLOOD MAPS - SHEET 11 (PDF | 10 MB)
• Appendix J DESIGNATED FLOOD MAPS - SHEET 12 (PDF | 16.5 MB)
• Appendix J DESIGNATED FLOOD MAPS - SHEET 13 (PDF | 21 MB)
• Appendix J DESIGNATED FLOOD MAPS - SHEET 14 (PDF | 18.5 MB)
• Appendix J DESIGNATED FLOOD MAPS - SHEET 15 (PDF | 22 MB)