DESIGN OF EMBANKMENT HEIGHTS FOR SHALLOWABOVEGROUND RESERVOIRS UNDERSTANDING RISK AND UNCERTAINTY

摘要

The design of deep classic cross-stream-type reservoirs has been well documented, but the design of relatively shallow aboveground reservoirs-less than twenty feet in depth-has not been as rigorous resulting in questions of proper design from a depth-storage volume versus cost perspective. This paper addresses shallow reservoir design parameters from the identification of the Hazard Potential Classification to the determination of risk and uncertainties through a methodic analysis that results in a selected embankment height. The everglades restoration project in South Florida includes several large aboveground reservoirs and stormwater treatment areas that are subject to extreme meteorological conditions in manner of cyclonic (hurricane) storm events. Also, subsurface investigations led design teams to the use of shallow reservoirs because of seepage concerns (karst region) resulting in extensive perimeter embankments for storage requirements. Hence, embankment heights were identified as a critical design feature requiring detailed analyses with respect to implementing a project that protects public safety, and to remain economically justifiable. Embankment height requirements are not strictly formulated in US Army Corps of Engineering Regulations and Manuals provide only general rules for their design. Therefore, the Jacksonville District reviewed and performed hydrologic and hydraulic analyses to identify and determine definitive design parameters, understanding the uncertainties associated with various approaches found in available literature. A corresponding risk and uncertainty analysis was formulated and used to identify probabilities of events occurring in relation to "typical" probabilities associated with other dam constructed features and their acceptable risk.