Abstract: There are tens of thousands of constructed earthfill dams in the world. Some will be removed because its benefits no longer outweigh their negative impacts on river ecosystems and communities. Some will fail. A dam failure is a traumatic event that affects communities for generations. Planners, owners, civil protection agents and valley communities need tools to foresee the time scales of flooding due to dam is overtopping.
This lecture describes contributions for a deeper understanding of the erosive processes that determine the breach evolution and consequent hydrograph. It attempts answers to the following questions:
– How do material discontinuities in zoned dams affect the kinematics and dynamics of breaching? What impacts in time to peak, on flow hydrograph and on bulk erosion rates?
– What hydrodynamic and soil mechanics processes are needed to construct a sound conceptual model for dam breaching – “as simple as possible, but not simpler”? How much detail is needed in describing hydraulic erosion, sloughing and undercutting?
– Given that some hydrodynamic processes do not obey Froude scaling and that bulk erodibility does not obey any hydrodynamic scaling, what can be learned from testing small laboratory dams and numerical simulations to understand scale effects?
Short bio: Rui M.L.Ferreira is a researcher and professor at Instituto Superior Técnico, Universidade de Lisboa, training students and conducting fundamental research in characterization of turbulence over rough walls and canopies, mechanics of bedload transport, and fluid-structure interactions and applied research involving modelling of debris-flows, dam-break flows and tsunamis. He coordinates the development of laboratory instrumentation, including PIV, optical flow and bedload measuring systems, and of the mathematical modelling tool HiSTAV. He is Associate Editor of Water Resources research, Journal of Hydraulic Engineering and Advances in Water Resources and has been guest editor in several international journals. Has been a member of the leadership team of the Fluvial Hydraulics Committee, Chair of the Experimental Methods and Instrumentation Committee of IAHR and is a IAHR Fellow.