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If the criteria of occurrence is not met, the Global and the Overall checks SUCCEED.
Breaching criteriaBreach flow criteria:
This criterion corresponds to step 5 of CUR Aanbeveling 113, 2008.
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where D15 and D50 are the minimum averaged values (only for sand and gravel soils) over a thickness of 5 m between the water line and the toe of the channel slope.
The type of sand (particle size) is a user-defined parameter: very fine sand, medium fine sand or coarse sand/gravel.
The program checks that the user-defined parameter is coherent with:
- the calculated diameter D50;5m if a Detailed check is performed
- the calculated diameter D15;5m and D5;5m is an Advanced Breach flow check is performed
In case a incoherence, the Overall result gives a Warning message.
In the current version of the program, it is not checked if the thickness is minimal 5 m. The average is performed over a thickness of 5 m, by not taking into account the none-sandy layers.
NOTE: The case where D50 < 200 μm is not checked but In case the user-defined sand type is "very fine sand", the breach flow criteria can't be checks and the program gives always that breach flow is possible and a warning message will be given in the Overall Results window.
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from depth | to depth z [m +GL(a)] | Average slope | |||
|---|---|---|---|---|---|
Not too Medium fine sand D50 > 200 μm and D15 > 100 μm | Fairly coarse Coarse sand/Gravel D50 > 500 μm and D15 > 250 μm | ||||
| Local slope | Average slope 0 - z | Local slope | Average slope 0 - z | ||
0 | -5 | 1:2 | 1:2 | 1:2 | 1:2 |
-5 | -10 | 1:3 | 1:2.5 | ||
-10 | -15 | 1:4 | 1:3 | 1:3 | 1:2.5 |
-15 | -20 | 1:5 | 1:3.5 | ||
| -20 | -25 | 1:6 | 1:4 | 1:4 | 1:3 |
| -25 | -30 | 1:8 | 1:4.67 | ||
| -30 | -35 | 1:10 | 1:5.43 | 1:6 | 1:3.75 |
| -35 | -40 | 1:10 | 1:6 | ||
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