Review of the Broadwater Assimilative Capacity Study

Abstract

As part of Gold Coast Water’s Coombabah Release Options Assessment a Broadwater Assimilative Capacity Study is being undertaken to assess the impact of a range of options to modify the current recycled water release strategy at the Gold Coast Seaway. A review has been called for the whole process and outcomes of the Broadwater Assimilative Capacity Study in relation to EPA’s licensing requirements and best engineering practices. The review will broadly address the appropriateness of the ebb-staged release scheme, adoption of the Gold Coast Estuarine Modelling Study (GEMS) model, dye test program, AD model calibration and the release scenario simulations. Especially, the review will critically appraise the adopted process for release scenario simulation and review the report prepared on the model simulations. In particular, the review will address details such as grid sizes, time step, model parameters, and simulation periods in relation to the proposed release windows. In this regard the scope of the review includes comment on the initial mixing zone model setup, tidal exchange ratio, transient flow characteristics of the ebb tide and role of coastal currents, wind and other parameters on dispersion.