Development of a Freshwater Management Tool to Support Integrated Watershed Planning for Auckland Waterways

Stormwater Conference

Auckland Council is responsible for the management of freshwater quality and quantity in the Auckland region. While developing strategies to manage our water resources, the Council will face a number of decisions and the community will be engaged on various options, their cost and benefit. Water resources strategies, particularly around freshwater systems, will primarily be developed and implemented through the Wai Ora – Healthy Waterways programme, including supporting outcomes identified through delivery of the National Policy Statement for Freshwater Management (NPS-FM) and Auckland Unitary Plan. The Council’s catchments have been organized into 10 watersheds and Integrated Watershed Plans are being developed for each. In future phases, action plans will be developed for each Integrated Watershed, which could include potential structural and non-structural interventions to improve fresh- and coastal water quality.

To support decision-making and community engagement, the Healthy Waterways programme has begun development of a regionwide dynamic modelling system called a Freshwater Management Tool (FWMT). The FWMT will be an integrated decision support system that represents the current state of the hydrology and water quality of the region’s watersheds, and simulates the potential effectiveness and cost-benefit of structural and non-structural interventions that could be implemented over time. The FWMT will provide outputs at varying spatial and temporal scales across Auckland’s varied land use types and freshwater bodies (rivers, lakes, wetlands and aquifers). The FWMT will be built using open-source, process-based, continuous simulation models. Continuous simulation is an important component of the approach, as management of freshwater quality requires prediction of the frequency, duration and magnitude of contaminant loads (annualized loads are insufficient in many cases). The FWMT will build upon previous modelling tools developed by Auckland Council, particularly the Contaminant Load Model.

The FWMT will be composed of two components: [1] a baseline hydrology and water quality model and [2] a stormwater management model to simulate the effectiveness of performance of stormwater management devices and non-structural measures. The baseline hydrology and water quality (“current state”) model will be used to characterize current catchment conditions; the selected modelling software is Loading Simulation Program – C++ (LSPC). The stormwater management model will be used to simulate the effect of structural and non-structural interventions on instream hydrology and contaminant levels; the selected modelling software is the System for Urban Stormwater Treatment and Analysis Integration (SUSTAIN). The specified models have been selected because they are process-based, continuous simulation models that can handle a wide array of pollutants, catchment conditions and implementation scenarios. At the same time, these models are free, peer-reviewed public-domain models that have been applied in catchments across the world including regulatory programs and case studies by United States Environmental Protection Agency.

Conference Papers

3. Development of a Freshwater Management Tool to Support Integrated Watershed Planning for Auckland Waterways.pdf

pdf
239 KB
28 Jun 2018

1420 - Caleb Clarke - Dev of a Freshwater Managment Tool.pdf

pdf
4 MB
28 Jun 2018