The application of a spatial Relative Risk Model at multiple scales in assessing the ecological risk to Australia’s tropical rivers
The tropical rivers of northern Australia are under increasing pressure due to environmental threats and human activities. The objective of this sub-project (sub-project 2) of the Tropical Rivers Inventory and Assessment Project (TRIAP) was to develop a risk assessment framework applicable to the key focus catchments and significant locations that meet stakeholder needs, within the region of the TRIAP.
An Ecological Risk Assessment (ERA) was undertaken at multiple scales: the broader TRIAP area encompassing 51 catchments; and the focus catchment scale (the Fitzroy River catchment, WA; the Daly River Catchment, NT, and the Flinders River catchment, Qld). In characterising risk in a semi-quantitative context, a Relative Risk Model (RRM) based on conceptual models of ecological risk developed with stakeholder input, was implemented within a SIS environment utilising data collected under sub-project 1 (Inventory and Assessment). The RRM was applied at both the broader tropical rivers region and at the focus catchment scale with the risk units being catchments and subcatchments respectively.
This paper presents the application of the RRM and results. Pressures and threats to ecological assets of tropical rivers are ranked for each risk unit and then combined with habitat and assessment endpoint ranks to produce a relative risk rank for each risk unit. As this is a relative model, comparisons can only be made within the defined risk area for which the model is applied. This method of characterising risk provides a useful tool in undertaking ERA across large geographic areas and at multiple scales. It is also produces a product that is practical in communicatiing the issue of ecological risk to multiple stakeholders.