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Tony L. Wahl. 2008. "Stability Analysis of Proposed Unlined Spillway Channel for Upper San Joaquin River Basin RM 274 Embankment Dam Alternative". Bureau of Reclamation, Report Number HL-2008-06.

Abstract: Potential headcut erosion of a proposed unlined spillway channel excavated through granitic rock was studied using the SITES water resources site analysis computer program distributed by the USDA. Model runs made using best-estimate values of key material parameters and upper and lower-bound limit values indicated that the spillway channel would not breach due to flows occurring during the probable maximum flood event. Further sensitivity testing showed that extreme values of the detachment rate coefficient, headcut erosion index, or representative material diameter are required for the model to predict a breach of the spillway. Modeling of lower operational flows predicted minimal damage to the spillway channel. The applicability of the model to this situation, uncertainties in model results and the influence of factors that are difficult to include in the analysis are discussed. A novel method for estimating the threshold stresses required to initiate erosion of monolithic rock is also presented.

Web Link: http://www.usbr.gov/pmts/hydraulics_lab/pubs/HL/HL-2008-06.pdf

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