THREE RECOMMENDATIONS FOR INCREASING WILLINGNESS OF COMMUNITIES TO WORK ON LANDSLIDE RISK REDUCTION IN OREGON (Invited Presentation)

Landslides are one of the most widespread and damaging natural, and sometimes human-induced, hazards in Oregon. The Oregon Department of Geology and Mineral Industries (DOGAMI) has worked on landslide risk reduction with many communities in Oregon. Based on these past projects, DOGAMI found three fundamental components that have increased community willingness to work on risk reduction and therefore overall project success. These three components are: 1) The use of light detection and ranging (lidar) data, 2) the inclusion of risk analysis, and 3) collaboration with the community before, during, and after the project.

Lidar data’s influences are two-tiered. First, it helps everyone understand the landslide hazard better because we all can see it much more easily. Being able to see the hazard increases trust in the science by removing some of the “science is a black-box” perception, which is sometimes very difficult to overcome. Once people trust the science, and understand the relevance to their community, they are more likely to perform landslide risk reduction.

Risk analysis demonstrates the potential for loss. We have been performing two types of risk analysis: exposure (what’s in the way) and loss estimation (number of potentially displaced people and property damage in dollars) using FEMA’s Hazus-MH methodology. For example, in a study of Clackamas County, we inventoried 2,885 landslides. Only after we showed that more than 7,000 residents and 3,000 buildings are located on large, deep landslides was the community moved to develop and prioritize risk reduction actions.

We have found that collaboration with a community before, during, and after the project results in more appropriate use of science to develop policy, leading to an overall increase in successful implementation. For example, in a study of the City of Portland, the City provided GIS data for the risk analysis portion of the project. One of these datasets was a neighborhood boundary map which helped everyone understand the spatial variability of risk throughout the City better and is proposed to be used for education and awareness in the high risk neighborhoods.

We have recently started work on a guidebook titled Landslide Risk Reduction: A Land Use Guide for Oregon Communities. Preliminary findings from this project will be discussed.