A probabilistic model for hazards related to sedimentation processes on alluvial fans in Davis County, Utah /
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| Other Authors: | , , , |
| Format: | Thesis Book |
| Language: | English |
| Published: |
1988.
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| Subjects: | |
| Online Access: | ProQuest, Abstract Link to OAKTrust copy |
| Abstract: | Debris flows have caused damage to developments on alluvial fans in Davis County, Utah, intermittently since the county was settled in 1847. The most recent damage occurred in the springs of 1983 and 1984 in response to rapid snowmelt; earlier damage resulted from cloudburst thunderstorms. The objective of this research was to develop a probabilistic model for evaluating hazards related to alluvial-fan sedimentation processes. The principal goal of any hazard model should be quantification of the hazard in meaningful terms which can be used for actuarial purposes, investments decisions, and engineering design. The model developed for alluvial fans in Davis County, Utah, is based on historic records to document the number and volumes of historic events, the total volume of the fan estimated from topographic maps, and the number of prehistoric events estimated from stratigraphy and geomorphology. Magnitude-frequency relationships are developed from these data. Exceedance probabilities are calculated for specific exposure times using a combination of binomial and extreme-value analyses of log-linear and non-linear distributions of event magnitudes. Sedimentation hazards are evaluated by comparing probabilistic event peak discharges and volumes to channel cross-sectional areas and debris basin volumes. Damage caused by sedimentation events includes collapse, translation, and flood-like inundation of structures; battering and lateral impact by boulders and debris; and clogging of surface drainage devices. A six-level intensity scale for sedimentation even damage is based on thickness of deposited sediment and damage to structures and vehicles. A model for hazard and risk management consists of recognizing and quantifying hazards and risks, and systematically analyzing alternative responses (continue current practices, modify the hazard, modify what is at risk, modify operation/procedure, or avoid the hazard). Probabilistic sedimentation hazard analyses can be integrated with other quantifiable hazard analyses (e.g., flooding and earthquake-induced ground failure) for assessment of multiple hazards. |
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| Item Description: | Typescript (photocopy). Vita. "Major subject: Geology." |
| Physical Description: | 2 volumes : illustrations ; 29 cm |
| Bibliography: | Includes bibliographical references. |