Murray Darling Basin Sustainable Yields Project: Prioritisation and Assessment Framework for Groundwater

摘要

Groundwater extraction is highly variable across the Murray-Darling Basin (MDB) with 84 percent occurring within six valleys and the majority of that from a small area of alluvial aquifer in each valley. Accurate groundwater modelling to assess sustainable extraction limits requires detailed data and considerable effort. It is probably only justified for aquifers where there is significant groundwater extraction. A prioritisation scheme is thus appropriate and one has been developed for the Murray Darling Sustainable Yields (MDBSY) project based on Groundwater Management Units (GMUs).Jt enables an appropriate level of effort to be focussed on 20 of the 96 GMUs that account for more than 75 percent of the groundwater use in the MDB. For each priority class, there is a minimum expected assessment standard. This prioritisation scheme has guided the application, adaptation and development of models for the MDBSY project, largely using existing models. Nonetheless, many of the models do not meet the minimum standard suggested by the criteria in the prioritization scheme. This has not prevented the attainment of project objectives, but does mean that some of the conclusions related to sustainable extraction may have lower reliability than desired. There are inconsistencies between the models in relation to calibration and assumptions that make a Basin-wide comparison of response to climate difficult. The prioritisation and assessment framework may have wider application than the MDBSY project, including the identification of knowledge gaps required to meet future policy and management requirements for groundwater in the MDB.