Document ID: chunk:federal_register_of_legislation:F2024C00760:reg:24:p24
Version: federal_register_of_legislation:F2024C00760
Segment Type: reg
Provision Reference: reg 24 (pt 24/36)
Character Range: 371637–374668

and evaporation, particularly over summer and especially in the northern parts of the Basin.
    12. Across the Basin the level of connection between surface water and groundwater is variable. For example there are strong connections between groundwater and surface water in alluvial valleys such as the Peel River while there is no connection in a number of western Basin areas (MDBA 2012; Tomlinson 2011).
Variability
    13. Climatic conditions in the Murray‑Darling Basin vary considerably from region to region and year to year. There is a strong east‑west rainfall gradient and a strong north‑west to south‑east temperature gradient. Rainfall is summer‑dominant in the north and winter‑dominant in the south (CSIRO 2008).
    14. The Basin also experiences considerable variation in annual inflow to its rivers—over the past 114 years inflows have ranged from a high of around 117,907 GL in 1956 to a low of around 6,740 GL in 2006 (MDBA 2010a, 2010b).
    15. Flow through the barrages near the Murray Mouth also varies widely depending upon a wide range of climatic conditions, including the federation and millennium droughts and the very wet periods during the 1950s and 1970s. The historical patterns of annual stream flow are modelled under without‑development conditions and represent this variability. At Wentworth on the River Murray, flow in the wettest 15‑year sequence (1950–1964) is 42% higher than the long‑term average. In the driest 15‑year sequence (1995–2009), flow is 32% lower than the long‑term average (MDBA 2010b).
    16. Multiple lines of evidence indicate that the tropics and tropical weather systems and their influences are expanding southward, exerting considerable influence on the climate of south‑eastern Australia, including the Murray‑Darling Basin. There is also evidence that the southern storm tracks that historically brought cool season rains to southern Australia have contracted toward the South Pole. If these trends in circulation patterns continue they will have significant implications for the climate and water resources of the Murray‑Darling Basin, potentially leading to a warmer and drier climate in the southern half of south‑eastern Australia (CSIRO 2010a).
Condition
    17. The condition of the Basin's surface water resources varies depending on a range of factors including location, climate and connectivity, the level of development, management arrangements, local activities, and an area's relationship with other parts of the system.
    18. Changes to the flow regime of the Murray‑Darling Basin's rivers have affected flood‑ and flow‑dependent species and ecosystems (Boulton 1999; Kingsford 2000; Kingsford & Thomas, 2004). The National Land and Water Resources Audit (NLWRA 2000) assessment of river condition indicated that the ecological health of Basin rivers was poorer than that required for ecological sustainability.
    19. In its Assessment of the ecological and economic benefits of environmental water in the Murray‑Darling Basin (2012), CSIRO found