The main objective of this test was to determine the erosion resistance of the vegetation and the cover layer during different levels of water flow intensity and under different circumstances. In this regard, a number of overflow tests have been done.
In this experiment, several factors were studied such as: the effect of different overflow heights and flows, the animal activity and the type of cover.
To achieve this objective, two types of tests were performed, some with the presence of a tree and others on a repair measure with a geotextile (EPDM) anchored with sandbags.
Procedure
The overflow generator was installed on several strips of the levee in the Living Lab Hedwige-Prosperpolder to simulate overflow of the levee which occurs when the water level of the river exceeds the height of the levee. The water is supplied to the generator via pumps. Water continuously flows down the slope of the levee via a demarcated test strip. The intensity of the overflowing water can be changed and cameras and other flow measurement devices are used to monitor the tests and state of the levee.
Monitoring and experiment data
Cameras and flow measurement devices are used to monitor the tests and state of the levee
Water
Max
Min
Mean
Standar deviation
Crest
0.16
-0.0
0.12
0.03
Upper
0.09
-0.21
0.06
0.03
Lower
0.17
0.0
0.13
0.03
Velocity
Max
Min
Mean
Standar deviation
VX_Upper
3.5
-1.6
0.42
0.95
VX_Lower
-0.32
-0.34
-0.33
0.0
VY_Upper
3.99
-0.37
2.15
0.62
VY_Lower
3.82
-0.52
3.35
1.02
Outcome
The main learnings of presence of a tree are: Burrows or holes that create contact between the surface water and the levee core are a major risk. And Collapse evolves very quickly and leaves no or little time for emergency response in a real overflow situation. The main learnings of presence of Testing repair measure are that the attachment method of the foil to the undamaged part of the levee is very important. There are many different types of anchors to attach the sheet, but once water can flow underneath the sheet it is not very effective anymore
