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Biomedical subjects

C Kirk Ziegler

Publications and source records attributed to C Kirk Ziegler.

3 recordsLinked to original sources
PubMed2006

Using mathematical models to assess sediment stability.

The application of mathematical models to a sediment stability study is presented, with an emphasis on using models as a component of an effort to develop, refine, and potentially validate a conceptual site model (CSM) for sediment transport at a study site. The utility of mathematical models is discussed, in which the modeling framework consists of linked hydrodynamic, sediment transport, and contaminant fate and transport models. Benefits and drawbacks of empirically based mechanistic models are presented. An approach for integrating modeling analyses into the development, refinement and validation of a CSM is provided. This approach focuses on a phased study that combines modeling and data-based analyses to test hypotheses related to the CSM and sediment stability. Uncertainty in modeling results is a primary concern in sediment stability studies, and issues related to model uncertainty are discussed. Finally, communication of modeling results to stakeholders is addressed.

Environmental Pollutants↗
PubMed2002

Evaluating sediment stability at sites with historic contamination.

The stability of cohesive sediment deposits during a rare storm is a critical component in the evaluation of remedial options at a contaminated sediment site. Estimating scour depths during a rare storm, and the resulting contaminant concentrations in the surficial layer of the bed, is necessary for comparing the efficacy of various remedial alternatives. Evaluation of sediment stability is accomplished using sediment transport analyses that employ quantitative procedures. Qualitative analyses or conceptual models can be useful for developing and validating quantitative analysis tools; however, qualitative techniques alone generally are insufficient for conducting defensible remedial alternative evaluations. The level of analysis used for a specific site depends on data availability, required level of accuracy, and time and budget constraints. A tier 1 analysis involves the use of approximate equations to produce order-of-magnitude estimates of scour depths during a rare storm. The second tier of this analysis scheme employs the development and application of a sediment transport model to evaluate bed stability. State-of-the-science sediment transport models have been effectively used as management tools for evaluating remedial options at several contaminated sediment sites. It should not be presumed that rare storm events cause catastrophic impacts at the site under review. Two case studies demonstrate that a rare storm is not necessarily catastrophic; significant increases in surficial bed concentrations caused by reexposure of elevated concentrations buried at depth in the bed will not necessarily occur during a rare storm. However, it is important to note that sediment stability is site-specific.

Environmental Monitoring↗