Upload
ava-windham
View
216
Download
1
Tags:
Embed Size (px)
Citation preview
11-04-23
Challenge the future
DelftUniversity ofTechnology
Dune erosion during storm surgesJaap van Thiel de Vries
Picture: Beach and dunes near Westenshouwen
2Titel van de presentatie
Dune erosion
Maximum storm surge level
Pre-surge dune foot
Post-surge dune foot
Pre-surge beach width
Post-surge beach width
Mean sea level
Dune erosion during storm surges
3Titel van de presentatie
Societal importance
Dutch safety policy against flooding:
•“Dijkringen”
•Weakest link in a “dijkring” determines safety against flooding
•Strength primary water defenses against normative conditions is assessed every five years.
•Strength dunes is assessed with empirical guideline elaborated from large scale dune erosion experiments
Dune erosion during storm surges
4Titel van de presentatie
Societal importanceHondsbosche en Pettemer sea defense Scheveningen
Head of Noord-Holland Head of Walcheren
Dune erosion during storm surges
5Titel van de presentatie
Thesis outline
Thesis outline:• Large scale dune erosion tests in the Deltaflume• Interaction of dune and swash• New approach in modeling near dune hydrodynamics• New approach in modeling near dune sediment
concentrations• Coupling of new physical insights in a 2DH
morphodynamic model
Objective: Improve our physical understanding of dune erosion in order to develop a more generic dune erosion model.
Dune erosion during storm surges
6Titel van de presentatie
Deltaflume experimentDimensions: 220m x 5m x 7m
Depth scale = 6
Irregular waves; Hm0=1.5m
Dune erosion during storm surges
7Titel van de presentatie
Deltaflume measurements
In-situ
Stereo Video
Dune erosion during storm surges
MOBILE FRAME
STEREO VIDEO
FLUME WALL
8Titel van de presentatie
Deltaflume results
Pressure sensors on flume wall: Suction tubes on shallow water frame:
Dune erosion during storm surges
duingolfschot
Korte (wind) golvenLange golven
9Titel van de presentatie
Deltaflume results
Incoming bore
Shore line
Reflected wave
Dune crest
Dune erosion during storm surges
10Titel van de presentatieDune erosion during storm surges
Modeling near dune hydrodynamics
The generation of long waves due to variations in the wind generated short waves
11Titel van de presentatieDune erosion during storm surges
Modeling near dune hydrodynamics
12Titel van de presentatieDune erosion during storm surges
Modeling near dune hydrodynamics
13Titel van de presentatieDune erosion during storm surges
Near dune sediment concentrations
Tbore
Hypthesis: High near dune sediment concentrations are caused by wave breaking induced turbulence that is injected in the water column over a short time interval and reaches the bed as a pulse.
14Titel van de presentatieDune erosion during storm surges
Near dune sediment concentrations
15Titel van de presentatieDune erosion during storm surges
XBeachNew physical insights are coupled in the morphodynamic model XBeach that:
• Solves both short waves (energy balance) and long waves (Nonlinear Shallow Water Equations);
• Includes a formulation that also relates the sediment concentration to the wave breaking induced turbulence pulses that potentially reach the bed;
• Includes the longshore direction.
16Titel van de presentatieDune erosion during storm surges
LEF Restaurant en BarDoelenplein 2, Delft
Google maps