Landslide Susceptibility along the Sea to Sky Highway


	Conclusion The goals of this project have been succesfully achieved. An analysis of the landslide susceptibilty along the Sea to Sky Highway has been completed using slope stability conditions, and a coupled slope and hydrological model developed by Montgomery and Dietrich (1994). Landslide susceptibility maps have been produced, including an overall map showing landslide susceptibility from Horseshoe Bay to Squamish, as well as closeups of the Porteau, Lions Bay, and Britannia Beach areas. Animations of the effects of increased steady state rainfall on slope stability for varied friction angles were produced, and three dimensional visualizations of landslide susceptibility, including two animations have been created. Overall, the results of this project provide a good first approximation for an overview of landslide susceptibility, but careful attention needs to be paid to the interpretation of the critical precipitation values, given the complexities of hydrology. The estimated precipitation intensity is an index of potential landslide susceptibility, but given the hydrological complexities of the area, they require careful interpretation for meaningful results. However, most landslides will be initiated during high intensity, rare storm events, so the approach taken in this project is sufficient as a first approximation. Additional field based studies would need to be conducted to supplement the model for more accurate interpretations of landslide susceptibility. The study area has steep slopes and thin soils, and Montgomery and Dietrich (1994) indicate that the model performs very well in this sort of terrain. The results obtained from this project appear to be consistent with historical landslide occurences along the Sea to Sky Highway, as well as with the location of existing landslide defenses. While there is a large amount of uncertainty in the accuracy of the results of this project, largely because of the many assumed parameters, the methods used in this project have been shown to provide a simple way of modelling landslide susceptibility over relatively large areas with minimal amounts of data. Acknowledgements We would like to thank the following people for their assistance in this project: Dr. Brett Eaton, Instructor of Hillslope Geomorphology, UBC; Dr. Brian Klinkenberg, Instructor of Advanced Issues in GIS, UBC; Jeff Phillips, Teaching Assistant for Advanced Issues in GIS, UBC; and a big thanks to Jose Aparicio for the many hours of help in the computer labs.

Conclusion

The goals of this project have been succesfully achieved. An analysis of the landslide susceptibilty along the Sea to Sky Highway has been completed using slope stability conditions, and a coupled slope and hydrological model developed by Montgomery and Dietrich (1994). Landslide susceptibility maps have been produced, including an overall map showing landslide susceptibility from Horseshoe Bay to Squamish, as well as closeups of the Porteau, Lions Bay, and Britannia Beach areas. Animations of the effects of increased steady state rainfall on slope stability for varied friction angles were produced, and three dimensional visualizations of landslide susceptibility, including two animations have been created.

Overall, the results of this project provide a good first approximation for an overview of landslide susceptibility, but careful attention needs to be paid to the interpretation of the critical precipitation values, given the complexities of hydrology. The estimated precipitation intensity is an index of potential landslide susceptibility, but given the hydrological complexities of the area, they require careful interpretation for meaningful results. However, most landslides will be initiated during high intensity, rare storm events, so the approach taken in this project is sufficient as a first approximation. Additional field based studies would need to be conducted to supplement the model for more accurate interpretations of landslide susceptibility.

The study area has steep slopes and thin soils, and Montgomery and Dietrich (1994) indicate that the model performs very well in this sort of terrain. The results obtained from this project appear to be consistent with historical landslide occurences along the Sea to Sky Highway, as well as with the location of existing landslide defenses. While there is a large amount of uncertainty in the accuracy of the results of this project, largely because of the many assumed parameters, the methods used in this project have been shown to provide a simple way of modelling landslide susceptibility over relatively large areas with minimal amounts of data.

Acknowledgements

We would like to thank the following people for their assistance in this project:

Dr. Brett Eaton, Instructor of Hillslope Geomorphology, UBC;

Dr. Brian Klinkenberg, Instructor of Advanced Issues in GIS, UBC;

Jeff Phillips, Teaching Assistant for Advanced Issues in GIS, UBC;

and a big thanks to Jose Aparicio for the many hours of help in the computer labs.