EAGE Local Chapter: Erosion investigation in the Hedwigepolder
About this event
17:00 – 17:50 – Welcome drinks & snacks
17:50 – 18:00 – Short introduction by Dr. Diego Rovetta
18:00 – 18:45 Technical talk by Chris Bremmer (Deltares) on:
Shallow geophysical research by Deltares
18:45 – 19:00 – Technical talk by Dr. Marc Hijma (Deltares) on:
Importance of geology for dike safety: case Hedwige polder
19:00 – Q&A and discussion
The event will be at Deltares’ patio (Boussinesqweg 1 Delft)
Backward erosion piping is an important failure mechanism for flood defences. It can occur during high water when the hydraulic gradient across the flood defence is high enough to initiate the formation of pipes by flowing water at the interface of a sand layer and a less permeable and more cohesive cover layer. If unmitigated, the erosion channel will progress upstream and may lead to subsequent failure of the flood defence. The assessment model that we use in The Netherlands are based on tests in homogeneous, sieved fluvial sand and hence it completely ignores geology! In large parts of the Netherlands, however, the sand below the flood defences consists of tidal sand, sand that has relatively high percentages of fines (clay, silt), often contains discrete clay and silt layers, and is much more cohesive than fluvial sand.
Two full-scale backward erosion piping field tests were executed in the Hedwigepolder, The Netherlands. The tests were aimed to validate our hypothesis that tidal sand has more resistance to piping than fluvial sand. Piping was initiated by infiltrating water into a completely enclosed body of tidal sand. In this talk I will show you all the highlights of this test, including our excavation after the test to track the pipe route, but also what it will mean for the assessment of flood defences in The Netherlands.
About the speaker:
Dr. Marc Hijma is a quaternary geologist working as a researcher on deltas, river systems and flood-protection with 20+ years of experience. He is a specialist on past and current sea-level changes, long-term evolution of near-coastal areas and the influence of the subsurface on the behavior of levees and other infrastructure. His experience is based on research both in The Netherlands and abroad. He gets inspired by bringing fundamental and applied research together in projects that benefit society.
For more information: https://www.eventbrite.co.uk/e/eage-local-chapter-netherlands-october-live-event-tickets-419454578937