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threshold under ambient spring conditions, and infiltration-induced failures are likely to be triggered by any increase in stage. The Pipal site is conditionally stable under ambient spring conditions, and is vulnerable both to infiltration and bank erosion.

Results indicate that the slow drawdown incorporated in the simulated flow regime permits pore-water pressure to dissipate sufficiently, and is not a factor in potential instability. In a wider context the work shows how site vulnerability, and potential remedies, can be identified relatively quickly using a combination of a comparatively sophisticated, seepage model coupled to two simple and widely accessible bank erosion and stability models. It also highlights the need to account for the three processes simulated here; comparison of the Factor of Safety data reveals the extent to which it is combinations of infiltration, hydraulic erosion and geotechnical failure that lead to bank failure. Simpler modeling approaches run the risk of overestimating bank stability.


The authors would like to thank Andy Collison and Tony Layzell for their assistance with the development of the Bank Stability Model interface.


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