When people think of Colorado and geologic hazards, they tend to think of big natural hazards that are often reported in the media, including landslides, avalanches and rockfall. But other little-known geologic hazards that can also wreak havoc on homes, commercial buildings and infrastructure, if not identified prior to construction.
“What might be the biggest surprise for some is building on the edge of the mesas could be potentially problematic,” said Colorado Geological Survey senior geologist Jonathan White. “While the edge mesas may offer the nicest views, they are potentially unstable. The edges are actively being eroded, and when they are weathered and full of water because of irrigation, they can be unstable – and have been problematic to a lot of homes already.”
White said that is just one example of the many types of geologic hazards the mapping project points out. Other potential hazards include rockfall, avalanche, debris/mudflow, poorly drained selenium hazards and even earthquakes.
“If you live near some of those fault lines there, there are precautions you can take in case of an earthquake,” he said. “For instance, you don’t put a heavy bookcase next to a child’s crib. Some of those are common-sense precautions, but there are things you can do if you live near a fault.”
Upon recognizing that many of these geologic hazards in the Uncompahgre River corridor were not properly identified, Montrose County recently partnered with CGS, Colorado Division of Emergency Management and Federal Emergency Management Agency to implement a comprehensive program of hazard identification and mitigation solutions. Now after approximately three years, that work is now available to the public in a new CGS digital map publication called Geologic Hazards Mapping Project of the Uncompahgre River Valley Area, Montrose County, Colorado.
The publication sheds light on how geologic conditions become geologic hazards, and what can be done to mitigate their impact.
The map data includes GIS datasets mapped at 1:24,000 scale and digital cartographic maps on 1:50,000-scale topographic base-maps that are in Acrobat Portable Document Format (PDF) file formats.
A 76-page report about the geologic hazards in the project area is also available for download as an indexed PDF file. The chapters include an overview of the hazard, mapping methodology and mapping results. There are, furthermore, specific discussions of risk assessment and hazard vulnerability, mitigation strategies and development considerations and recommendations for future land-use planning, for each potential hazard.
“This report will be an important reference for the practicing professional engineer, hydrologist and geologist,” said Vince Matthews, director of the Colorado Geological Survey, “but is also suggested reading for landowners, land-use planners, land developers, landscape architects, and contractors who work in the Uncompahgre River Valley.
“Property owners can use the report to learn how to recognize potential geologic hazards, read their geotechnical reports with better understanding, how to landscape property and manage water use to reduce the effects of problematic rock and soil, and understand methods to prevent or reduce hazard potential.
Geologic Hazards Mapping Project of the Uncompahgre River Valley Area, Montrose County, Colorado (Open File Report 09-01) is available free as a digital download from the CGS on-line publication website at: http://geosurvey.state.co.us/pubs/online/Pages/GeologicHazardsMappingoftheUncompahgreRiverValleyArea,MontroseCounty,Colorado.aspx
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