Porirua catchment and estuary collaborative planning

Streamlined Environmental is providing science support to the Te Awarua-o-Porirua Whaitua collaborative planning process, which is implementing the National Policy Statement for Freshwater Management in Porirua Harbour and its surrounding catchment.

The Whaitua committee is charged with developing objectives and limits that are integrated across freshwater streams and the harbour receiving environment. Dr Malcolm Green is serving on the Modelling Leadership Group, which has developed and implemented a plan for developing a range of “source-to-sea” contaminant models for predicting freshwater and harbour outcomes under different possible management scenarios and for setting contaminant load limits. A wide range of contaminants is being examined, including sediments, nutrients, metals and pathogens. Models that simulate contaminant sources, transformations and transport have been coupled and are being used to predict freshwater and harbour “attributes” such as periphyton, sedimentation, bed-sediment metal concentration and E. coli in the water column and in shellfish flesh. In addition to the source-to-sea models, economic and social models are being developed, and cultural issues are being studied. Dr Ngaire Phillips (Streamlined Environmental) is developing Bayesian Network models and information sheets to inform the Whaitua committee’s decision-making. An important project component, which will ramp up later in 2018, will be developing ways of communicating modelling results to the committee and the wider public in readily understandable ways.

The Whaitua committee’s recommendations will ultimately inform Greater Wellington Regional Council’s regional plan.

porirua sedimentation