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Technical support for BOSS BREACH!
Dear Mr. Maeder!
I am a student at the Univervesity of Agricultural Sciences in Vienna - Institute of geotechnical engineering, working on a thesis about risk and reliability of small earthen dams . To model a failure due to overtopping or piping, i use the BOSS BREACH software. To model the flow of the flood wave along the downstream reach i use BOSS DAMBRK with the breach parameters from BOSS BREACH.
Now i have a problem with defining the right time step for the BREACH model, because the computed max. peak discharge in the analyse output file is not the same as shown in the graphic output file. Often i vary the time step in very small steps until both values are equal, but this is very laboriously and sometimes there is a difference of more than 100 % between this two peak outflow values.
Can you tell me what time step should be used to get an agreement between this two values. I will give you the parameters i use in my model:
Homogeneous dam without inner core:
Dam height: 1 - 10m
Dam length: 50m
Dam crest width: 3m
Downstream and upstream slope: 1:2 ;no grass cover
Storage surface area: 500 - 5000 sq m
Inflow hydrogaph: always 1 cms ;no outflow at time zero
D50: 2mm
D90/D30: 2,5
Porosity: 36%
Inner friction angle: 30°
Cohesive strengh: 0
Unit weight: 20000 N/cu m
Manning value: 0,03
Thank you for your efforts!
Sincerely!
Gunther Thaler
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Linear Mode
