Multi-scale three-dimensional mapping of coastal cliff erosion and coastal landslides in California: Applications in digital photogrammetry and GIS

Digital photogrammetry is increasingly being used to assess shoreline change. This method has traditionally been used to produce orthophotographs from digital aerial photography; this study focuses on developing techniques of deriving 3D topographic models from the digital photogrammetry workflow. A limiting factor to this technology is obtaining high-resolution aerial photography of spatial and temporal interest. A Coastal Aerial Mapping System (CAMS) was developed to collect aerial photography on demand for areas of interest. This aerial mapping allows for rapid response to storm events and provides a cost-effective method of establishing a continual monitoring program in erosion hazard areas.; Coastal cliff retreat along the central California coast is episodic, occurring in response to single large storms or seismic events. This study addresses the processes of episodic and short-term coastal cliff retreat through the analysis of seacliff failure styles and retreat magnitudes in central California using aerial photography and digital photogrammetry. The earliest data set is vertical aerial photography taken the day following the Loma Prieta earthquake. More recent photography was collected in the winter of 1998 during the 1997–98 El Nino. Digital photogrammetric techniques are used to identify coastal cliff erosion processes due to the winter storms and the earthquake. Results suggest that on large-scale climatic events such as the 1997–98 El Nino have a greater impact on coastal cliff erosion than do even large earthquakes.; The California Department of Transportation (Caltrans) is exploring solutions to the problems faced with keeping coastal Highway 1 open and safe after large landslides close or damage the road while minimizing impacts to the Monterey Bay National Marine Sanctuary (MBNMS) below the road. As a contribution to developing a highway management plan, and in order to advance the fundamental understanding of coastal landslide processes along this stretch of coastline, a technique is developed to quantify the historical volume of sediment that enters the littoral system from coastal slope failures. The volume losses are related to the complex geology of the region to determine what geological characteristics are most important in determining higher sediment yield from coastal landslides.