A LANDSLIDE HAZARD RATING SYSTEM FOR NORTHEAST OHIO

The northeastern portion of Ohio is categorized as a region of high landslide susceptibility and hazard potential. The areas that are most susceptible to landslides are located along steep-sided valleys and along roads cuts through weak glacio-lacustrine silts and clays. Landslide hazard includes any direct or indirect hazard posed to humans and properties because of landslide activity. In order to identify slopes exhibiting varied degrees of hazard potential and to help engineers prioritize their remediation efforts, a new landslide hazard rating system for Northeast Ohio is proposed.

Forty nine slopes with different hazard levels (low, moderate, high) were selected for development of the hazard rating system. These slopes were selected so that they were representative of the variations of geometric, geologic, hydrologic, and traffic conditions in the study area. Univariate, bivariate, and cluster analyses were performed on the collected data to identify parameters that are most significant in distinguishing between slopes of varying hazard potential. Statistical analyses identified six of the twelve parameters as significant. These six parameters (recharge area, slope height, slope length, average daily traffic, degree of vehicle risk, and length of roadway affected) were included in the final rating system. In addition, three other parameters (liquidity index, slope angle, decision sight distance) that were not found to be statistically significant but have been found to be important by the existing rating systems were retained in the final rating system. The nine parameters were assigned scores using an exponential scale ranging from 3 to 81. For each site, the scores for the nine parameters were added to obtain the total scores. Sites with total scores < 200 were categorized as low hazard potential sites, those with scores between 200 and 300 as moderate hazard potential sites, and those with scores > 300 as high hazard potential. The final system rated 23 sites as low hazard potential sites, 15 sites as moderate hazard potential sites, and 11 sites as high hazard potential sites.