Topic: Rainfall recovery in the Murray Darling Basin 2010

[Harley Pearman]

Rainfall recovery in the Murray Darling Basin - ONE YEAR ON

During 2009, I covered the drought affecting the Murray Darling Basin and much of Victoria (See Drought Statements 2009 - New South Wales and Victoria Thread). One year on and over the weekend of 27-29 August 2010, I was fortunate enough to take the time off work to venture into the Murray Darling Basin around Parkes and Dubbo to take a look at what is happening.

A remarkable turnaround is evident. Not only has the rains returned but the region visited is looking reasonably healthy and extensive crops have been planted. Further, much of what was planted appeared to be in a healthy state.

I noted water in farm dams and rivers and streams around Orange were flowing and even overflowing. Evidence of the drought is still visible in which many eucalyptus trees are still stressed but overall there is some recovery. It is known that the Hume Reservoir on the Murray River upstream of Albury Wodonga is now at 50% capacity, the highest it has been for a number of years.

Heavy August rains around Orange has caused a number of rivers and Suma Park Dam just east of Orange to overflow. There is also some road damage such as potholes on the Mitchell Hwy around Orange due to heavy rainfall and water impacting on the road pavement. Repair crews were seen Friday and Sunday fixing damaged sections of road.

I have prepared some rainfall statistics for 2010 for eight localities across inland New South Wales using data from the various weather stations (Weatherzone) to show the remarkable turnaround that has occurred. Additionally a rainfall plot for 2010 for the Murray Darling Basin from 1 January to 30 August 2010 (BOM Land and Water) is also attached. Generally the wheat sheep belt has received worthwhile falls for the year and it is a significant turnaround compared to the same period for 2009. The plots are attached below.

Harley Pearman

[Harley Pearman]

September 2010 rainfall for Murray Darling Basin (NSW)

Following on from the previous post, September rainfall for inland New South Wales continues to be positive which is helping to remove the short term deficits. It is noted that much of the rainfall fell during the first half of the month while the second half was relatively dry. Still rainfall was either average or above average and the trend for 2010 when compared to 2009 is positive.

Rainfall continues to recover for country New South Wales with all centres in the table (attached) recording from 23% to 62% above average falls to the end of September 2010.

A significant turnaround has occurred at Hume Reservoir on the Murray River. At the beginning of September, the reservoir was just on 50% capacity. As at 2 October, this had jumped to 81.25%, a massive rise of 949,375 megalitres. Flooding rains in the upper Murray catchment has been captured by the dam during the month for storage. At the same time in 2009, the dam was at 33% capacity. 

I have prepared a rainfall analysis using data from 8 centres across country NSW showing rainfall for September. The raw data is sourced from Weatherzone dated 2/10/2010.

Harley Pearman

[Harley Pearman]

Rainfall plots for the Murray Darling Basin September 2010

The rainfall plot for the Murray Darling Basin (Shown in the black line) shows that the wheat sheep belt has continued to record satisfactory rainfalls for 2010. The best falls for September fell in the South East of the Basin and along the Great Diving Range (Up to 200 mm). The slopes and plains also fared well with 50 to 100 mm falling. The north east of the basin received good falls as well.

The interannual plot or Difference - September 2009 / September 2010 is showing a healthier situation within the Basin for New South Wales. Generally rainfalls to date within the Basin are either average or as much as 50 mm over and above the average. Only in North West Victoria are falls still below the average. It is clear that the wheat sheep belt is currently satisfactory for 2010.

It should be noted that even though one good year has removed the short term rainfall deficits, much more rainfall would be required to remove the very long term deficits built up over many years.

The two plots described are provided below from the Land and Water site - Bureau of Meteorology dated 2/10/2010. It is noted that the "Interannual Difference Plot', eg 2009 / 2010 appears to be new to the site and it is now possible to compare the current year to a previous year.

Harley Pearman

[Harley Pearman]

October Rainfall 2010 (Southern New South Wales receives a very wet month)

During the month of October, the drought was formally declared as being over for much of New South Wales. Rainfall for the month of October continues to be positive as shown in the table provided below. However, in particular, the Southern Murray Darling Basin including Southern New South Wales has had a very wet month. In particular, Wagga Wagga received 166.2 mm of rain for the month while Albury Airport received 154.8 mm of rain for the month (Figures are to 9 am 31/10/2010). As a result, Albury and Wagga Wagga have surpassed their average annual rainfall totals for a normal year. It was also wet in Griffith and Orange. I have collated the rainfall data from the weather stations for the selected localities across the Murray Darling Basin (NSW only).

To show the recovery first hand, back in early February 2010, I drove down to see what the Hume Reservoir looked like towards the end of the drought. Early February 2010, Hume Dam was at 17% capacity and such low levels had been common for a number of years. During March 2009, the dam fell to 1 or 2% capacity. This time last year it was hovering around 38 or 39% capacity due to low runoff and low rainfall in the upper catchments. Fast forward 8 or 9 months to October 24 2010, Hume Reservoir is declared full with water releases occurring to mitigate flooding upstream. I am fortunate as shown below to have taken photos of the dam wall and water level before the drought broke and after the drought broke at the same location. Following a number of floods and high rainfall the turnaround along the Murray River is truly amazing after just one season.  


Harley Pearman

[Michael Bath]

Thanks for posting this information Harley. It gives a great perspective of how things have improved this year.

[Harley Pearman]

November rainfall 2010 (Murray Darling Basin New South Wales)

When reviewing the November rainfall figures for the Murray Darling Basin, it is becoming apparent that:-

1 - The drought is well and truly broken.
2 - Too much rain is occurring in some localities.

The rainfall figures derived from local weather stations for November for the 8 urban centres chosen across inland New South Wales is attached below as a table. Of particular interest:-

1 - Wagga Wagga has far exceeded its normal yearly rainfall.
2 - Orange on the Central Tablelands has had more than double its rainfall when compared to the same time last year.
3 - Tamworth had a wet November receiving 154.2 mm.
4 - Albury Airport has had 2 months in a row where the monthly rainfall has exceeded 100 mm.

I have made three recent trips into the Murray Darling Basin for storm chasing and I have noticed that too much rain is occurring in some localities. Waterlogged paddocks and now flooding has occurred around the Central West and South West Slopes. There has also been much damage to crops and cropping lands due to higher than normal rainfall.

Much of inland New South Wales has received above average rainfall in the order of 25 to 100 mm above average for the month. The highest anomalies for above average rainfall have occurred in the following localities:-

1 - Inland North East New South Wales west of Narrabri and Moree.
2 - Gunnedah region.
3 - South west slopes / central west slopes near the towns of Cowra, Yass and Young.

The wettest areas are found right along the slopes and plains west of the Great Dividing Range. The Rainfall Deciles for November from "Water and the Land" Bureau of Meteorology and dated 7/12/2010 is also attached. It shows much of the Murray Darling Basin within New South Wales receiving "Above average Rainfall" to "Very Much Above Average Rainfall". Some smaller areas have had rainfall in the "Highest on record" decile.


Harley Pearman

[Harley Pearman]

December 2010 rainfall for the Murray Darling Basin (NSW)

Please find below the final rainfall statistics for 2010 for the selected centres that I have compiled from the local weather stations. There are several amazing rainfall figures for 2010 including:-

a) Wagga Wagga - A new yearly rainfall record was set for a total of 1,019.4 mm. Such rainfall has never occurred here.
b) Orange:- An amazing total of 1,592 mm fell during the year.

When compared to the average rainfall and rainfall for 2009, the year 2010 is a marked stand out for the Murray Darling Basin.

Much of the December rainfall occurred in the first few days of the month. In particular at Dubbo, 115 mm of its near 168 mm fell during the first 6 days of the month. I was at Dubbo at the time to witness the flooding that occurred along the Macquarie River. A similar storey occurred at Parkes. Wagga Wagga was impacted by two big storm events resulting in its high monthly total of 151 mm and flooding occurred there as well.

The drought broke but by December, too much rain fell and significant flooding resulted in many areas. Looking at the daily weather records for the selected centres, December ended drier in such centres as Albury, Dubbo and Wagga Wagga and some drying out started to occur in the south. However at Orange (Central Tablelands), 104 mm of rain fell on the 25/26 which boosted the monthly total to 299.9 mm. So while some parts of the Basin at least in New South Wales started to dry out in the latter half of the month, heavy rains continued in other areas.

The table referred to is attached below.

Harley Pearman   

[Shaun Galman]

Hi guys,

Some pretty astounding totals there Harley! I have every rain event/totals for this year here at Lightning Ridge N.S.W. on a calender that I might add up today (being the years end) and post.

I'm amazed at the shots of the Hume wall as I saw it just before the flooding -as your first photo shows, about 30-40 feet down to the water line. When my friends showed me a shot of it at capacity I was amazed!

We are about to get a further influx of water into the Coocoran Lake as I went up and checked the Narran River at Angledool N.S.W. on Tuesday the 28th December and it was around 1.6mtrs (on the gauge at the Jim Harper bridge just NW of Angledool) which is very close to the 1.87mtrs reached in the major flooding event back in March 2010.

I'll keep an eye on the Weetalibah crossing 30k's North of Lightning Ridge on the Castlereagh Highway now as it should begin to flood across the road again any time now.

Kindest regards.     

[Harley Pearman]

The 2010 Drought statement for the Murray Darling Basin

Finally to conclude this topic from myself, when reviewing the drought statement for 2010 for the Murray Darling Basin, it is identified by the Bureau of Meteorology that no region contained within the basin is afflicted by short term drought. The 2010 drought statement show the entire basin free of drought and not suffering short term rainfall deficiency.

This is the big turnaround for 2010 when compared to the situation during 2009.

The final 2010 rainfall deficiency plot produced on the "Water and the Land" site Bureau of Meteorology dated 1/1/2011 for the year 1 January to 31 December 2010 year is attached below.

Harley Pearman

[Shaun Galman]

Hi guys,

That's a nice drought (or lack of) chart to see Harley!

I have tallied the totals for us here at Lightning Ridge N.S.W. and it came to a fairly impressive 717mm for 2010.

Kindest regards.