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Activity Name:

N-OF03 Overflow Test (Reference)

Activity Numbre:

65

Activity type

Strength test

Involved Workpackage

Flood defences
Emergency response
Knowledge infrastructure

Objective

Perform an overflow test on a Dutch levee in (visually) good condition. It is considered as a reference case for the Dutch levee in the Hedwige-Prosperpolder.

Activity Brief descriptor

During the N-OF03 reference test, detailed hydraulic measurements were performed. PTV, LSPIV, Lidar measurements during the experiments.

Linked to theme(s):

Breaching
Animal- & vegetation-induced anomalies
Erosion processes
Temporary levee repairs
Levee survey & monitoring technique
Prolonged collaboration

Activity Time

Start Date:

Dec. 6, 2021, 8 a.m.

End Date:

Dec. 8, 2021, 5 p.m.

Active time length:

Days:

3

Hours:

14.0

Other:

Location

Levee stretch:

VI

Coordinates/ Latitude (WGS):

51.34789

Coordinates/ Longitude (WGS):

4.22973

Coordinates/ Altitude (mTAW):

12.06

Descriptor:

Landward slope of levee.

Other references:

Lambert coordinates: X=140313.0 m, Y=226465.6 m.

Data

Data: 1

Data type: Timeseries
Description: Timeseries of Discharge, Water Height and Current Velocity in different positions on the levee slope.
Date availability: None
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Data: 2

Data type: Photo imagery
Description: 2 portals with in total 4 cameras are used to take surface photographs of the levee slope at different times during and in between overflow activity. The surface images in between overflow blocks show damage and vegetation evolution.
Date availability: None
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Data: 3

Data type: Hydraulic measurements
Description: Other monitoring data, including PTV, LSPIV, ...
Date availability: None
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Relationships with other activities

  • Activities that are linked to 65/ N-OF03 Overflow Test (Reference) :

    No activities

  • DB_id: 65/ N-OF03 Overflow Test (Reference)

  • DB_id: 65/ N-OF03 Overflow Test (Reference) linked to the following activities:

    DB_id: 88/ P2C Overflow tests

Detaled information about the activity

Pre-conditions

Levee slope in visually good condition.

Activity Descriptor

11 blocks of overflow, for a total of 14:40 hours. PTV measurements executed on 6/12/2021; LSPIV and hi-speed camera on 7/12/2021.

Equipments

Equipment: 1

Overflow generator
The setup is described in Vercruysse et al. (2022): "Design and application of an overflow generator." (Ref WL2022R20_047_1)

Monitoring & Sensors

- Overhead cameras (4) - Acoustic water height sensors - Electromagnetic current velocity sensors - Discharge sensor (EM or acoustic)
Description of the hydraulic conditions of the overflow. The setup is described in Vercruysse et al. (2022): "Design and application of an overflow generator." (Ref WL2022R20_047_1)

this activity does not have sensors

Limits

During Activity

During the course of the experiment however, it is seen that the normal evolution as in other reference tests is ongoing: slight soil erosion and increasing exposure of vegetation root systems. However,there is no critical damage being created and the overall slope is holding. During the last afternoon, holes were drilled to evaluate whether this would lead to damage, which appeared not to occur.

Post-activity conditions

The levee slope stayed in good condition apart from the slight erosion described during the activity. No critical damage.

Immediate Results

A levee in a well maintained state without any obvious anomalies, is able to withstand elevated discharges (specific discharges up to 500l.s-1.m-1) for several hours.

Results /Conclusion

Factual data report: https://stowanl-my.sharepoint.com/:w:/g/personal/llhpp_stowa_nl/EX5yYnuJ-EBBjoKAxAwg8LkBef8ra9V_-GHjzbkz0Was8g?e=pyaUSq Annexes: https://stowanl-my.sharepoint.com/:w:/g/personal/llhpp_stowa_nl/EWIzoxIhxopCryc6744YgHYBBWr_0fhoGpJ_1pSy0_tM2w?e=pY8Hc6

Infrastructure Knowledge

An integration report will be added later (February 2023) as knowledge document.
The integration report discusses insights gained from both the steady overflow and wave overtopping tests. under development
under development

Other key information