UPSW - Southern Rural-Urban Boundary Auckland City

This case study outlines a pilot trial of a DSS which was developed by the Urban Planning that Sustains Waterbodies (UPSW) research project.

The UPSW DSS was developed and trialled as a part of the Auckland Councils (AC) draft unitary plan in order to assess the potential effects of a range of future urban development scenarios in the southern rural urban boundary of Auckland as well as South-eastern Manukau Harbour. The wider goal of the UPSW project is to assist and inform local government in planning sustainable development of New Zealand infrastructure in a manner that protects and enhances the values and services associated with urban waterbodies.       

Method

The study focused on assessing changes to estuarine sediment quality and the health of estuarine benthic invertebrate communities. The pilot DSS makes its predictions of these environmental indicators based on models (or versions of models) that have been previously developed and applied outside of the UPSW research project.

There are three aspects to the design of the pilot DSS. Firstly, it incorporates indicators of environmental, economic and social wellbeing. Secondly, it links a number of distinct methods in order to make predictions of outcomes under alternative urban development and stormwater management scenarios. These methods include: deterministic models; a probabilistic model; non-market valuation; look-up tables populated through expert elicitation techniques; and index construction. Thirdly a number of the methods have been developed specifically for incorporation in the pilot DSS. These include a model for estimating the costs of catchment-scale stormwater management, a stream ecosystem health model and a method for predicting social wellbeing indicators from precursor environmental attributes.

 

UPSW framework2

Structure of the piloted DSS

 

The pilot DSS operates as a single entity executed from an MS Excel platform. The inputs to the system are the characteristics of urban development options (UDOs), specified for each of several planning units (PLUs) within a study area. The outputs from the system are summary indicators of environmental, economic and social wellbeing, provided for each reporting unit within the study area. Typically, each planning unit corresponds to a stream catchment and contains a single stream reporting unit (SRU). The estuarine environment to which these streams discharge is divided up into a number of estuary reporting units (ERUs), each of which is representative of relatively homogeneous bed-sediment characteristics and sediment dynamics.

Findings and Conclusions

For this pilot study eleven scenarios were modelled ranging from stormwater management to land use changes including the treatment at source of metal inputs. From these modelled changes the results were represented either through environmental indicators  or as social and economic indicators;

Environmental indicators:

  • Sediment metal Concentrations
  • Benthic Heath metals score (BHMmetals)
  • Mud content of bed sediments
  • Benthic health mud score (BHMmud)
  • Sediment accumulation rates

Social and Economic Indicators:

  • Social (Water body use i.e. swimming, walking, surfing, shellfish gathering)
  • Economic

Based on the UPSW model three major scenarios; a combination of the initial eleven scenarios, were predicted to have a significant effect on the estuarine receiving environment over and above the effects from the baseline scenario if current earthworks and stormwater treatment controls (or worse) are applied. However much of the effect from the three major development scenarios could be mitigated if the best available earthworks and stormwater treatment controls are applied.         

As with many models there is room for improvement within this DSS. An aim of its further development is to incorporate a wider range of inputs which represent a more realistic view of the environment. Such improvements could include enhancements of environmental indicators to include a full spectrum of uses and values which are actually held by local communities in an effort to better represent the function of waterbodies within an urban area. Additions could also be made relating to social indicators of cultural wellbeing as is mentioned by the authors. 

Associated Models

Urban Planning that Sustains Water (UPSW)

Urban Planning that Sustains Waterbodies (UPSW) is a pilot spatial DSS, the model building and testing came to completion in December 2012.

References

Moores, J., Cameron, M., Harper, S., and Batstone, C (2013). Urban planning that sustains waterbodies: southern RUB case study. Prepared by NIWA and Auckland Council Research, Investigations and Monitoring Unit. Auckland Council working report, WR2013/006