The real-time operational models assimilate measured flows and water levels during hindcast, ensuring an accurate description of the state of the river at the time of forecast. We forecast tributary inflows using the NAM Rainfall-Runoff model. We then compute groundwater exchange and bank-side evapotranspiration losses utilising our MIKE SHE software. Using a MIKE 11 (now MIKE HYDRO River) hydrodynamic model, we compute flows and storages in the river, at weirs and in wetlands.
The right amount of water at the right time
MIKE OPERATIONS integrates the models with the real-time data feeds. This ensures that the models always operate with the most recent catchment rainfall, irrigation demands and river flows. All demands, inflows and outflows from the model are aggregated from weir to weir to generate initial release hydrographs. We take into account river flow travel times, which depend on the flow itself.
The MIKE 11 model returns measures of how close the initial hydrographs are to satisfying the different targets, including:
- delivery of irrigation water on time
- delivery of environmental flows
- maintenance of user-specified water levels at weir ponds
With these measures, we identify corrections to the initial hydrographs. We then apply the optimiser AutoCal to fine-tune these to obtain optimum operation. Built-in descriptions of weir capacities and constraints ensure that the optimised set points can be implemented without contravening present river infrastructure status. This includes:
- capacity constraints in the river
- the rates of change of discharge at weirs
- information on the capacity of the gates if they are temporarily out of service
Based on information about the present state of the river, as well as optimisations conducted several times a day, it is possible for State Water Corporation to run a ‘leaner’ river. This means only water that is needed to meet demands is released, reducing flow transmission losses. It also leaves more room (air space) for water storage in the river channel and in the ponds upstream of the weirs. This additional air space allows weirs more flexibility in operating the river. In addition, it provides storage for unexpected inflows and water orders that have been rejected by irrigators.