Open Cut » Environment
The objective of this research has been to further develop an understanding of the requirements for successful design, operation, management and approvals relinquishment for constructed watercourse diversions at mine sites in the Queensland coal mining industry. This has been undertaken through a series of investigations and reviews.
Review of watercourse diversion performance in the Bowen Basin -
The first component of the research has been a review of the performance of 60 constructed watercourse diversions, 17 of which have been constructed to a set of hydraulic and geomorphic criteria developed in an ACARP project in 2002. This review revealed that the design and performance of new diversions undertaken to the ACARP criteria has improved; the performance of older diversions is declining; 85% of diversions are in poorer condition than adjoining reaches; five factors have been identified that limit improvement in diversion condition; and that the current design criteria require refinement for sediment dynamics and vegetation establishment. A highly positive outcome from this review is that the oldest of the diversions constructed to the ACARP 2002 criteria are considered by both regulators and experts in river health and waterway management to be on a trajectory suitable for relinquishment of approvals and management responsibility.
The diversion performance review was undertaken using a diversion evaluation framework modelled on the Monitoring, Evaluation, Improvement and Reporting (MERI) Framework adopted in the natural resource management industry. Through the passage of this project this MERI framework was refined and updated to identify criteria for successful constructed watercourse diversion operation and relinquishment.
The investigation has identified the criteria necessary for successful constructed watercourse diversion operation and relinquishment. Further the investigation has placed these criteria in a defined watercourse planning framework and a defined watercourse evaluation framework.
Design standards and approaches have been reviewed and refined as a fundamental basis for successful diversion operation. However performance standards for other criteria within the evaluation framework have not been developed.
Recommendations for further work have been made in relation to develop performance standards for the identified diversion evaluation criteria such as long term vegetation condition along agreed and defined vegetation succession trajectories. These criteria and standards need to be linked to a stakeholder evaluation process. It is also recommended that the outcomes of this project be included in a current government review into the approval process for diversions.