Guidelines for stormwater runoff modelling in the Auckland region

Auckland Regional Council, Beca Carter Hollings & Ferner Ltd
Auckland Regional Council
Publication date:

These guidelines present a recommended method for the application of the U.S. Soil Conservation Service1 rainfall-runoff model to catchments in the Auckland Region. They are based largely on Technical Release No. 55 (TR55) prepared by the U.S. Soil Conservation Service (SCS, 1986).

The Soil Conservation Service (SCS) model has been selected for stormwater management design in the Auckland Region on the basis of an evaluation against gauged catchments (BCHF, 1999a, 1999b, 1999c). Those reports provide the background to the selection, calibration and validation of the method. Streamflow data from the gauged catchments have been used to select input parameters for the model (soil classifications, times of concentration, etc.) and to validate the model. The model is recommended for use in stormwater management design in the Auckland Region. It has been designed as a standard tool that will provide consistent results from different users. It is suitable for:

  • assessing the effects of landuse change,
  • modelling both frequent and extreme events,
  • applying to distributed (a network of sub-catchments) or lumped catchments
  • and simulating natural systems as well as engineered systems (such as pipe networks).

The model can be applied using a number of available software packages to predict runoff volumes, flow rates, and the timing of peak flows. Peak flow rates can also be estimated using an alternative graphical method. 

Auckland Regional Council technical publication TP108

Prepared for Auckland Regional Council by Beca Carter Hollings & Ferner Ltd

First edition, April 1999


Last updated: 2017-09-25