Monte Carlo with ARR 2019 “Impervious Losses”

[mardi.medwell-squier@ghd.com]

Hi everyone,
Has anyone successfully run a Monte Carlo analysis on an urban catchment using the “impervious losses”? It seems to me that only the “PA” losses are being varied. If I adjust the “directly connected” and “indirectly connected” losses in line with the MC out file for the run I am trying to replicate then I get much higher flows, but if I don’t adjust the impervious losses then it matches. Are the urban losses intended to be treated as fixed, or is there a trick I have missed?

[Benson Liu]

Hi Mardi,

Currently only the pervious losses are varied in the Monte Carlo simulation, the impervious losses do stay constant. This is because the loss distribution used for pervious areas is based on research conducted on rural catchments, I believe further research would be needed to see whether the loss distribution for pervious areas is also applicable to impervious areas or whether a new distribution would need to be used.

Kind regards,

Benson

[Author]

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