The technical report and its appendices summarize the analyses and input used to create the floodplain maps. Watershed modelling is a technical exercise, and therefore these reports are technical in nature. Reports marked with an asterisk (*) may be of most interest to community members.
Chemainus River Flood Mapping Program, Part 1 - Floodplain Mapping Report* (22 pages)
An overview of the study, process used to create floodplain mapping, and recommended next steps.
Appendix A: Surveys and Water Level Measurements (11 pages)
Describes the survey data used to create the floodplain model.
Appendix B: Hydrology (15 pages)
Describes how water flows through the watershed and the scenarios used to develop flood mapping for the study area.
Appendix C: Chemainus River Geomorphic Atlas* (43 pages)
While we often think of rivers as unchanging, historical records show us that watercourses shift over time due to processes like flooding, sedimentation, blockages, and erosion. The geomorphic atlas summarizes landforms that affect how water flows through the Chemainus River floodplain. It includes hazard mapping that identifies where there is risk of physical changes to the river channel, providing important information for land use planning and hazard management.
Appendix D: Hydraulic Modelling (29 pages)
Describes how a hydraulic model that simulates flood events was created and the results of the modelling process. The hydraulic model can be used to predict potential future flooding impacts in the area.
Appendix E: Coastal Modelling (32 pages)
Because the Lower Chemainus River watershed meets the ocean at the Chemainus Estuary, the study includes coastal flood considerations as part of floodplain mapping. This report describes the process for integration of coastal considerations.
Appendix F: Flood Mapping Methodology (10 pages)
Describes the two mapping outputs created for the Lower Chemainus River.
The outcome of the technical work described above is updated flood mapping for the Lower Chemainus Watershed. Click here to view the maps.