Landslide Assessment: West Salt Creek Landslide
Mesa County, Colorado
Western Water Western Water & Land, Inc. (WWL) performed an evaluation of possible inundation areas in response to potential future failure and renewed movement of the debris resulting from the West Salt Creek Landslide. Potential inundation areas were delineated by using USGS Laharz™ software to model the planimetric area of the inundation hazard zones resulting from renewed movement of the landslide debris.
The West Salt Creek Landslide occurred on May 25, 2014 near the town of Collbran, Colorado, close to the headwaters of West Salt Creek. The slide covers an estimated area of 2.1 square kilometers (550 acres) and has an estimated release volume of 30 million cubic meters (m3). The slide is characterized as a rock avalanche consisting of at least five phases, including the rotational slump of an Upper Block in combination with the resulting rock avalanche and a series of local debris flows within portions of the landslide mass. The Upper Block has an estimated volume of 50-62.5 million m3 and subsequently pushed the 30 million m3 landslide mass downgradient. Surface runoff formed a small sag pond (pond) behind the Upper Block, within the void created as a result of the rotational slump.
The Laharz model forecasts were used to assess potential inundation areas resulting from future failure and renewed movement of the existing slide debris resulting from the West Salt Creek Landslide. Applicability of the model to the slide was assessed by comparing the actual geometry of the slide debris to the inundation areas predicted by model simulations designed to replicate the existing landslide. The comparisons showed that the model could be used to provide a reasonable estimate of the predicted inundation areas resulting from the release of material through rock avalanche and/or de bris flow mechanisms at the West Salt Creek Landslide.
Mesa County, Colorado
Western Water Western Water & Land, Inc. (WWL) performed an evaluation of possible inundation areas in response to potential future failure and renewed movement of the debris resulting from the West Salt Creek Landslide. Potential inundation areas were delineated by using USGS Laharz™ software to model the planimetric area of the inundation hazard zones resulting from renewed movement of the landslide debris.
The West Salt Creek Landslide occurred on May 25, 2014 near the town of Collbran, Colorado, close to the headwaters of West Salt Creek. The slide covers an estimated area of 2.1 square kilometers (550 acres) and has an estimated release volume of 30 million cubic meters (m3). The slide is characterized as a rock avalanche consisting of at least five phases, including the rotational slump of an Upper Block in combination with the resulting rock avalanche and a series of local debris flows within portions of the landslide mass. The Upper Block has an estimated volume of 50-62.5 million m3 and subsequently pushed the 30 million m3 landslide mass downgradient. Surface runoff formed a small sag pond (pond) behind the Upper Block, within the void created as a result of the rotational slump.
The Laharz model forecasts were used to assess potential inundation areas resulting from future failure and renewed movement of the existing slide debris resulting from the West Salt Creek Landslide. Applicability of the model to the slide was assessed by comparing the actual geometry of the slide debris to the inundation areas predicted by model simulations designed to replicate the existing landslide. The comparisons showed that the model could be used to provide a reasonable estimate of the predicted inundation areas resulting from the release of material through rock avalanche and/or de bris flow mechanisms at the West Salt Creek Landslide.