| The Integrated Planning Decision Support System (IPDS) is designed as a decision support system (DSS) to assist governments and communities in evaluation of geological hazards, vulnerability, and risk. The IPDS system incorporates the Geographic Information System (GIS) Geographic Resource Analysis Support System (GRASS) and engineering numerical models within a Graphic User Interface (GUI), to provide the user with comprehensive modelling capabilities for geological hazards, vulnerability, and risk assessment. The methodology that IPDS follows for the evaluation of hazards takes into account the weight of each influencing factor within hazardous geologic processes. IPDS interactive algorithms compute the following parameters for each cell (based on the maximum resolution of the data): the related hazard, the vulnerability to geological hazards, and the risk. One purpose of this DSS is the definition of land-use suitability categories for urban planning.; This DSS incorporates the following information: topography, aspect, bedrock and surficial geology, structural geology, geomorphology, soils (geotechnical data), land cover, land-use, hydrology, precipitation (annual average and probable maximum), Federal Emergency Management Agency floodway maps (1986), and historic data to assess hazards. IPDS is designed to assess any "generic" hazard, such as debris flows, subsidence, and floods, with probable maximum precipitation and seismicity as triggering factors for susceptibility scenarios. The regular items considered in vulnerability analysis are (1) ecosystem sensitivity, (2) economic vulnerability, and (3) social infrastructure vulnerability. The risk is assessed as a function of hazard and vulnerability.; The area of Glenwood Springs, Colorado (USA) was selected to evaluate this model. Glenwood Springs lies at the junction of the Roaring Fork and Colorado Rivers, surrounded by the steep peaks of the Colorado Rocky Mountains. The Roaring Fork River occupies a narrow valley incised into complex and relatively incompetent lithologies. Large parts of the valley have had intensive sheet erosion, debris flows, and hyperconcentrated floods triggered by landslides and slumps. The latter come from unstable to extremely unstable slopes in the many tributary channels on the surrounding mountainsides, causing concentration of debris in channels and a large accumulation of sediments in colluvial wedges and debris fans that line the valley. The semiarid climate, characterized by occasional fast melting of heavy snowpack and/or intense, short duration spring and summer thunderstorms, greatly decreases slope stability.; The area of Glenwood Springs was analyzed with IPDS. The IPDS model delineated excellent areas for future urban development, as well as providing insights into areas of high risk in residential, commercial, and assembly sites. Hazard-susceptibility maps were developed for debris flows, floods, and subsidence using algorithms which subjectively weighted the controlling variables. A sensitivity analysis of these weightings was performed for the debris-flow map. The results of the model can be used to guide planning and management of existing or proposed development. (Abstract shortened by UMI.)... |
