Water depth in the Middle Waitemata Harbour, represented on a flexible grid.
NIWA has recently upgraded its modelling software for simulating the dispersal of sediments and contaminants in coastal waters.
The new software represents water depth on a ‘flexible grid’. This allows the user to zoom in on water flow and sediment transport in areas that are complicated or of particular interest, such as valuable habitats or near stormwater discharges. The model also simulates clumping of fine sediment particles when washed from freshwater into saltwater, which affects the way they disperse and settle.
The software is up-and-running and being used to determine patterns of dispersal of urban contaminants, such as zinc and copper, in the Middle Waitemata Harbour.
These patterns are being used to predict build-up of heavy metals in harbour bed sediments over the next 100 years, to help guide urban planning and the design of stormwater networks.