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Monday, July 02, 2007

Rainfall Records for Robertson wrong - June 2007

The official rainfall data for Robertson - for June 2007 - from the Automatic recording station (at the Pie Shop) are incorrect.
When compared with the manually read station, in Caalong Street, Robertson, you can see that the official record is grossly understated.
(Data sourced from Bureau of Meteorology "Rainfall totals by station" for June 2007, accessed via the website: - "Monthly rainfall totals for Australia" - click on Rainfall Data - "Rainfall totals by station".)

I reported to the Bureau of Meteorology that incorrect readings were showing, over the June long-weekend, when it was bucketing down in Robertson, but the official station was not showing true records (compared to Caalong St).

I have been advised that the matter has been investigated, and it is put down to "telemetry problems", - "
However it was emphasised that there is no simple solution and this has been problematic now for many months, but please be assured that the Bureau is determined to solve the problem as quickly as possible."

While I was assured that incomplete records were being "voided", however, that has not prevented a clearly incorrect record being entered into the "official records" for Robertson for June 2007.

As a matter of comparison, Robertson scored 546.8 mm, Moss Vale scored 270.6 mm, and Bowral 285.0 mm. Fitzroy Falls did well, with 454.0.

The wettest reported station in NSW was Gosford with 644.2 mm. Interestingly, the Hunter Valley did not receive as much rain as the coastal areas, such as Gosford, Norah Head (574.6 mm) Newcastle (529.6). However, the size and shape of the Hunter Valley is such that the rainfall run-off accumulates in the Maitland area - where they got 379.5 mm. The rain which fell further up the valley - eg, Scone (220.8 mm), Singleton (240.0 mm), Cessnock (Nulkaba) got 351.9 mm, etc, although generally not huge amounts of rain, all that rain run-off accumulates in the lower Hunter Valley, as a flood.

Macquarie Rivulet
in flood.
un-named waterfall
at "Amaroo".
By contrast, Robertson's rain run-off is divided into four separate catchments
  • Upper Kangaroo Valley (Tallowa Dam on the Shoalhaven River)
  • Upper Nepean River (to the Nepean and Avon Dams)
  • Wingecarribee River (to the Warragamba Dam)
  • and Macquarie Rivulet (which makes pretty waterfalls over the escarpment, down Macquarie Pass), and causes floods in Albion Park, before running into Lake Illawarra.

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