Waikato River water quality modelling for Plan Change One

Dr Tim Cox developed a catchment water-quality model for the entire Waikato River catchment using Streamlined’s Contaminant Allocation and Simulation Model ( CASM). The model was developed to support, and advance, the technical analysis underpinning Waikato Regional Council’s Plan Change One, which focuses on managing and mitigating nutrient, sediment and bacteria impairment in the catchment. The model simulates annual nitrogen and phosphorus loadings from both point sources and diffuse sources aggregated across 74 discrete sub-catchments. It includes spatially variable nutrient attenuation and calculates median river concentrations at multiple instream compliance points. The model was used to spatially quantify the distribution of source loads, across landuse sector and sub-catchments, assess appropriate target threshold concentrations, and investigate various mitigation and allocation strategies. It was also used to assess areas of model uncertainty and associated implications for planning.
For more information contact Tim Cox by email at tim@streamlined.co.nz.