Archive for the ‘Murray Darling Basin’ Category
This is the third post covering the January 2011 floods in northern Victoria. Part I described how the floods unfolded and Part II described the hydrology of the Loddon catchment and how its history has affected flood behaviour. This final post covers the climatic influences on the floods. The floods themselves are discussed here, and affects on the family farm in Kerang are shown here.
Northern Victoria’s rainfall is influenced by the El Niño–Southern Oscillation (ENSO; spring–summer), Indian Ocean Dipole (IOD; winter–spring) and Southern Annular Mode (SAM; winter). Correlations of northern Victorian rainfall with simple indices are -0.51 for SOI May–Jan, ‑0.48 and -0.45 for two IOD indices May–Jan, and -0.25 for SAM for winter rainfall.Recent research has linked exceptionally wet conditions in south-eastern Australia with the combination of La Niña and a negative Indian Ocean Dipole (-IOD) (Ummenhofer et al., 2009; Ummenhofer et al., 2011).
The -IOD is associated with exceptionally warm waters off north-western Australia resulting in ‘north-west’ cloud bands that bring flooding rains into northern Victoria. The recent extended drought in Victoria has been characterised by an absence of these weather patterns. While central and north-western Australia have become wetter, this rainfall source has been conspicuously absent from south-eastern Australia.
This post examines the hydrological influences on past and present flooding leading to the January 2011 floods in northern Victoria. The floods themselves are discussed n Part I here, and affects on the family farm in Kerang are shown here. Part III on climatic influences is here.
Local data used are daily flows at Laanecoorie Reservoir on the mid Loddon River, and daily rainfall from the Newstead and Cairn Curran rain gauges upstream. Hydrological issues concern long-term catchment change and flow data. These affect the assessment of historical floods on the Loddon River.
The Wentworth Group of Concerned Scientists have withdrawn from engaging with version 2 of the Murray Darling Basin Authority’s plan to return sustainable environmental flows to the MDB. The first plan was withdrawn under controversy with fierce opposition from irrigators within the basin, largely because of the way it had been introduced and how the cuts were perceived. The original plan comprehensively reviewed water yield and use catchment by catchment. The results provided scientific estimates of the reductions needed to sustain an environmentally healthy system while retaining core regions of high yield irrigation.
So what is the main issue? The original plan had estimated that if 6,983 Gigalitres were recovered, environmental targets would be met with high confidence, and if 3,856 GL were taken back, they would be met with low confidence. The number in the v2 draft 1,000 GL lower than the low confidence figure, so leaves pretty much bugger all (a technical term meaning bugger all) hope of achieving the desired outcome. The Wentworth Group have pulled out of the formal process. Their statement is provided here and GetUp are organising a petition (follow the above link) and other actions to demonstrate the level of public support for water reform. If you feel strongly, please sign.
I suspect the wet year and temporary recovery of water storages has taken the pressure off and the weaker draft plan is the result. This is what happens when science gets jettisoned in favour of political compromise.
Proper recovery of environmental flows doesn’t necessarily mean that irrigators are thrown to the wolves. The industry doesn’t distinguish well enough between effiency, yield and volume in assessing water futures. The first draft plan didn’t help in that respect at all, and failed to take an integrated approach, concentrating on reducing institutional risk to the MDBA. Hopefully, I can make some time to go into more detail in another post.
This post reviews some of the events that led to the northern Victorian floods of January 2011. Part II looks at the hydrological influences and Part III on the climatic influences on the floods. Recommendations for the flood review are made in Part III.
There are two flood enquiries happening in Australia at the moment. The one in Queensland is understandably much higher profile because of the loss of life and damage caused. It has the powers of a Royal Commission, so can subpoena, call witnesses and cross examine.
Victoria’s enquiry is a review. Former Police Chief Neil Comrie has been appointed to examine matters extending from flood prediction and warning all the way through to access to emergency funding and government services. Public meetings are being held in affected areas and written submissions are being taken until May 27.
The biggest difference is the Review is more reflective and will address the information delivered, whereas the Commission is investigative and is charged to assess contributing cause to the disaster and its management. It can interrogate.