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Upper Rangitaiki Flood Forecasting Model


The Bay of Plenty Regional Council (BOPRC) commissioned Ewaters Ltd (Ewaters) to develop an Upper Rangitaiki Catchment Model using InfoWorks RS (Free Edition) software. This project aimed to demonstrate the practicality of using the model for flood forecasting during real events. The model forecast under real events can assist the Matahina Dam Company and BOPRC flood management department in evaluating flood situations for better decision-making. The predicted inflow to Matahina Dam can further serve as input for optimizing dam operations.


The project scope includes:

  • Creating an Upper Rangitaiki InfoWorks RS model, operable with InfoWorks RS Free Edition.
  • Reviewing and improving sub-catchment hydrological models.
  • Calibrating the model using the July 2004 event.
  • Setting up the model for EBOP staff to run with real event data and practicing with the January 2012 rainfall data as a validation event.
  • Preparing a flood forecasting model operational manual with step-by-step instructions.

Model Extent

The Upper Rangitaiki River Catchment covers an area of 2852 km2 upstream of the Matahina Dam. The model encompasses this entire catchment area, including the Rangitaiki River from the Matahina Dam to approximately 14 km upstream of Murupara. Smaller tributaries were trimmed for model simplification, except for the Whirinaki Tributary and Waihua Tributary. The model includes two hydrological dams: the Matahina Dam and Aniwhenua Dam.