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Transient hazard model using radar data for predicting debris flows in Madison County, Virginia

Environmental and Engineering Geoscience

By:
, , and
DOI: 10.2113/10.4.285

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Abstract

During the rainstorm of June 27, 1995, roughly 330-750 mm of rain fell within a 16-hour period, initiating floods and over 600 debris flows in a small area (130 km2) of Madison County, VA. We developed a distributed version of Iverson's transient response model for regional slope stability analysis for the Madison County debris flows. This version of the model evaluates pore-pressure head response and factor of safety on a regional scale in areas prone to rainfall-induced shallow (<2-3 m) landslides. These calculations used soil properties of shear strength and hydraulic conductivity from laboratory measurements of soil samples collected from field sites where debris flows initiated. Rainfall data collected by radar every 6 minutes provided a basis for calculating the temporal variation of slope stability during the storm. The results demonstrate that the spatial and temporal variation of the factor of safety correlates with the movement of the storm cell. When the rainstorm was treated as two separate rainfall events and a larger hydraulic conductivity and friction angle than the laboratory values were used, the timing and location of landslides predicted by the model were in closer agreement with eyewitness observations of debris flows. Application of spatially variable initial pre-storm water table depth and soil properties may improve both the spatial and temporal prediction of instability.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Transient hazard model using radar data for predicting debris flows in Madison County, Virginia
Series title:
Environmental and Engineering Geoscience
DOI:
10.2113/10.4.285
Volume
10
Issue:
4
Year Published:
2004
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Environmental and Engineering Geoscience
First page:
285
Last page:
296