A key problem in unifying sediment assessment and management approaches is in defining the hierarchy of decisions within a management framework. A basin-scale framework should be comprised of two principal levels of decision making; the first for basin-scale evaluation (site prioritisation) and the second for site-specific assessment (risk ranking). High priority, high risk sites and sites prioritised for management for socio-economic objectives should then be evaluated for management options. Although it is site-specific risks and objectives that will be managed, solutions may involve actions in other parts of the river basin (e.g., source control). A basin-scale assessment involves the balancing of a Conceptual Basin Model (CBM, which considers the mass flows of particles and contaminants, screening level assessment of sediment quality and archived data), and basin-scale objectives (BOs) to generate a Basin Use Plan (BUP). The Basin Objectives should define the ecological, regulatory and socio-economic goals for both the river basin (and its outlet to estuaries and the sea) and specific parcels of sediment. The development of a Basin Use Plan balances the CBM and the BOs, and should then result in a site prioritisation for further management that best meets the objectives of all stakeholders. On the other hand, site-specific assessment and management is characterised by tiered assessment and the determination of site-specific risk. Management options are driven by site-specific impact on BOs, site-specific risk, technical and economic feasibility and regulations. The proposed conceptual approach to basin-scale sediment management provides a possible frame-work for addressing the complexities inherent in managing sediments at both a basin-wide and site-specific scale.
