Flowpath Engineering Portal
TP108 Catchment Flow Calculator — Auckland Stormwater Design
Calculate catchment flows to Auckland Council TP108 standards. Determine time of concentration, peak flows, and detention requirements for NZ resource consent applications.
What this tool does
TP108 Methodology
Calculate catchment runoff using Auckland Council's TP108 technical publication methodology for stormwater management and resource consent compliance.
Time of Concentration
Determine time of concentration using overland flow, channel flow, and pipe flow components with standard NZ methods.
Peak Flow Estimation
Calculate pre- and post-development peak flows for multiple storm return periods to determine required attenuation.
Detention Sizing
Size on-site stormwater detention to attenuate post-development flows back to pre-development rates as required by Auckland Council.
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Open TP108 CalculatorPart of the Flowpath Engineering suite of free civil engineering tools for New Zealand.