Hydrologic modelling in the Hunter River for salinity management planning

A generic integrated water quality and quantity simulation model (IQQM) has been implemented in several inland regulated river systems in NSW for water resources management planning. It is also being implemented in the Hunter River system upstream of Greta. One of the main roles for the IQQM Hunter will be to investigate options for managing salinity in the Hunter River. IQQM operates at a daily time step and comprises four main components. These are an instream water quantity module, an instream water quality module, rainfall-runoff module and a salinity generation module. IQQM is designed to provide more reliable information relating to issues such as environmental flows and water quality than is possible with the existing monthly simulation models. These models have been used for water resource management planning studies in inland rivers in NSW and the Hunter Valley for almost 20 years. Implementation of IQQM Hunter has involved a multiple step calibration process. This firstly involved calibration using data from streamflow gauging stations and a known sequence of demands by water users. This was followed by testing the functioning of the algorithms simulating the demand of water users and the operation of storages to ensure satisfactory operation. Streamflow sequences were synthesised using the Sacramento rainfall runoff model and calibrated against recorded data. The generation of salinity sequences were based on data from a network of 20 continuous conductivity probes, together with data from industries in the valley and geological data. The final step involved calibration of salinity and flow routing behaviour, using non-linear routing, and assuming fully mixed flow. The results of model calibration will be presented in the paper and the quality of the calibration discussed. A description of the model will also be presented.