Southeastern Manukau Harbour / Pahurehure Inlet contaminant study: implementation and calibration of the USC-3 model

Malcolm Green
Auckland Regional Council
Publication date:

The main aim of the Southeastern Manukau Harbour / Pahurehure Inlet Contaminant Study is to model contaminant (zinc, copper) and sediment accumulation for the purposes of, amongst other things, identifying significant contaminant sources, and testing efficacy of stormwater treatment options.

This report describes the implementation and calibration of the USC-3 model (Urban Stormwater Contaminant) for the Study. The model, which functions as a decision-support scheme, predicts sedimentation and accumulation of contaminants (including zinc and copper) in the bed sediments of estuaries on the “planning timescale”, which is decades and greater. Because the USC-3 model makes explicit use of estimates of future heavy-metal and sediment loads from the catchment, it is truly a predictive model compared to, say, simply extrapolating past heavy-metal concentrations in harbour bed sediments. Because future sediment and heavy-metal loads will change according to management practice and policy, model predictions can be used to compare performance of competing development scenarios and to evaluate efficacy of zinc source control of industrial areas. In addition, the model tracks the movement of sediments and contaminants, which enables links between sources (on the land) and sinks (in the estuary) to be identified. This facilitates targeting of management intervention.

Prepared by the National Institute of Water and Atmospheric Research Ltd, NIWA for Auckland Regional Council. 

Auckland Regional Council technical report TR2008/057

Last updated: 2018-09-26