A summary of the significant water events, major water initiatives and improvements in water information occurring during the reporting period are explained.
The Ord region experienced low flows during 2009–10 as a result of the hot and dry conditions caused by above average evapotranspiration (ET) and maximum daily temperatures.
Water allocations in the region were not affected, as the annual water entitlements are only at 41% of the entitlement limit, and there is enough surplus water stored in Lake Argyle to administer entitlements and flow release obligations.
Major storages were affected by the hot and dry conditions and as a result of diminished inflows decreased by 18% from the start of the reporting period.
The upper Ord River and Negri River, a primary tributary of Ord River, contribute most of the inflows to Lake Argyle, the primary surface water resource in the region. Flows in these rivers were below average during 2009–10.
Wet season flow (November to April) was generally well below the 50th percentile for the catchments. Total annual flow in the Negri River was 383 GL, below the mean annual flow of 503 GL (Figure W1). Total annual flow in the upstream reach of Ord River was 349 GL, well below the mean annual flow of 1834 GL (Figure W2).
Figure W1. Total monthly flow along Negri River during 2009–10 compared with long-term percentiles
Total annual flow during 2009–10 in the lower Ord River was 2557 GL, also below the mean annual flow of 6977 GL. Flow throughout the year was generally equivalent to the 10th percentile in all months (Figure W.3).
Low flows throughout the Ord region are likely to be the result of the hot and dry conditions experienced during 2009–10, as a result of above average ET and maximum daily temperatures.
Figure W4 shows the location of the gauging stations used as the source of data for Figures W1 to W3.
Figure W4. Map of the location of gauging stations used for flow graphs in Figure W1 to W3
The Ord-East Kimberley Expansion project is a major initiative of the Western Australian Government. The State committed $220 million from the Royalties for Regions fund under the Ord Irrigation Expansion Project and a further $195 million was contributed by the Commonwealth Government via the East Kimberley Development Package.
The initiative will develop 80 km² of land for irrigation on the Weaber Plain in the Keep River catchment over the next two years, subject to environmental approval from the Commonwealth Government. Infrastructure planned includes irrigation distribution canals, drainage and roads. The development would increase the irrigated land by 50% and the first land sales would occur in late 2011. A further 80 km² of irrigation land is planned to be developed in the Keep River by 2013.
The total potential area for irrigation expansion is shown in Figure W5.
Figure W5. Map of Ord River Irrigation Area expansion
The Northern Australia Sustainable Yields project, completed by the CSIRO in 2009, provided critical information on current and future water availability for 13 regions in northern Australia.
A comprehensive scientific assessment was completed for the Ord region as part of the larger Ord-Bonaparte region.