Available soil water-a practical communication tool in

southern NSW

Michael CashenAgricultural Climatologist

michael.cashen@industry.nsw.gov.au

Acknowledge contribution from John Smith, Ian Hume & Sam North

My Talk

Case study site - Deniliquin Explore rainfall Links with research outcomes ~ SEACI

phase 1 Comparing periods 61-90 & 91-09 using PAW The future 2030 ~ unseen risks?

Case study: Deniliquin

Deniliquin yearly rainfall

Deniliquin yearly rainfall - Post Office (1863-2010)

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Federation drought (1900-2006)

World War II

(1936-1945)

‘Big Dry’ (1997-2009)

Data:http://www.longpaddock.qld.gov.au/silo/

Autumn outside the box

Deniliquin autumn rainfall trend (1863-2010)

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100110120130140150160

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Autumn 11 yr mov average

Data:http://www.longpaddock.qld.gov.au/silo/

Estimated PAW 61-90

ETc Wheat: Median monthly pan * Pan factor (0.72) * Crop Coefficient KcPan factor variant ~Sam North Pers Comm, 20th June 2011

Estimated PAW Deniliqin 61-90

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Median 61-90 ETc wheat (pan) 61-90

A tale of two periods -rainfall

Median rainfall Deniliquin

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Median 61-90 Median 91-09

Data:http://www.longpaddock.qld.gov.au/silo/

A tale of two periods- ETc (Wheat)

Comparison of Wheat ETc (pan)- Deniliquin

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ETc wheat (pan) 61-90 Etc wheat (pan) 91-09

Data:http://www.longpaddock.qld.gov.au/silo/

A visual comparison of PAW

A tale of two periods Denilquin PAW

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100

Jan Feb Mar Apr May June July August Sept Oct Nov Dec

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Median 61-90 Median 91-09 ETc wheat (pan) 61-90 Etc wheat (pan) 91-09

Data:http://www.longpaddock.qld.gov.au/silo/

Quantifying the difference

Rainfall ~ ETc comparison Deniliquin

-70.0

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Rainfall - ETc (pan) 61-90 Rainfall - ETc (pan) 91-09

Data:http://www.longpaddock.qld.gov.au/silo/

The future?

Deniliquin rainfall projections 2030

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CSIRO projection 2030 A1B 10th percentile CSIRO projections 2030 A1B 50th percentile

CSIRO projections 2030 A1B 90th percentile Median rainfall 61-90

Data:http://www.longpaddock.qld.gov.au/silo/

What about autumn?

Comparison of CSIRO projections and rainfall Deniliquin 91- 09

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CSIRO projection 2030 A1B 10th percentile CSIRO projections 2030 A1B 50th percentile

CSIRO projections 2030 A1B 90th percentile median rainfall 91-09

Given the findings of SEACI phase 1 (i.e. link between STR and temperature), are we at risk of under estimating the impact of CC ?

Conclusion

- Autumn rainfall in decline since mid 80’s.

- Strong linkage to intensification of the Subtropical

Ridge (SEACI Phase 1)

- Autumn decline reducing growing season length

and Plant Available Water for growth in spring

- Current CSIRO/BoM 2007 projections not indicating significant autumn declines

References

CSIRO and Australian Bureau of Meteorology, 2007,Climate Change in Australian, Technical report 2007.

CSIRO (2010) Climate variability and change in south-eastern Australia: A synthesis of findings from Phase 1 of the South Eastern Australian Climate Initiative (SEACI)

The Centre for Australian Weather and Climate Research, 2007, Understanding the anthropogenic nature of the observed rainfall decline across south-eastern Australia, CAWCR Technical Report No. 026

Deniliquin seasonal rainfall trends

Deniliquin seasonal rainfall trends (1863-2010)

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Summer 11 yr mov average

Autumn 11 yr mov average

Winter 11 yr mov average

Spring 11 yr mov average

Data:http://www.longpaddock.qld.gov.au/silo/

Monthly median rainfall 61-90

Median rainfall Deniliquin

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Median 61-90

Data:http://www.longpaddock.qld.gov.au/silo/