Community-based wind erosion monitoring across Australia 1

DustWatch Report October 2019 Dust activity Highest October record since records began in 2005 Wind strength Average for the month of October

Groundcover Lowest across multiple Local Land Services since records began in 2001

Rainfall Very little rain recorded; driest 18 month in some areas Land management Ongoing drought management in most areas

Dust activity We recorded an average of 65 hours of dust activity across our 21 long-term sites in October 2019 (Figure 1). The previous record of 16 hours in October 2009 – the year of the 'Red Dawn' dust storm– was exceeded by 49 hours in 2019. The main reason for the increased number is that the extent of the area experiencing extended dry period is larger and reaches further east that in 2008–09. Dust impacted coastal areas with all but one of the 20+ coastal monitoring stations recording over the daily national benchmark for PM10 on 25-26 October. In Tamworth dust caused six days over the national PM10 daily benchmark, the same number as the last 17 years at Tamworth combined. With wind strength likely to increase between now and February 2020, this dust activity will continue or increase unless substantial rainfall triggers widespread vegetation growth. Real-time data from all our monitoring sites are at: Rural air quality network – live data

Figure 1 Hours of dust activity (number in brackets) at each DustWatch site in October 2019

Community-based wind erosion monitoring across Australia 2

Groundcover The area with more than 50% groundcover (green colours in Figure 2 and Table 1) has declined sharply from last month, especially in the Local Land Services North West (64%) and Central West (51%) where values are now at their lowest since MODIS records began in 2001 (Table 1). Very little of the Local Land Services Western Region (34%) is now above 50% groundcover, leaving the remainder (66%) at increased risk of wind erosion.

Figure 2 Groundcover for October 2019 as determined from MODIS by CSIRO

Table 1 Percentage of each NRM (natural resource management) with cover >50% for October 2018 to October 2019

Date Central West

Mallee Murray North Central

North West

Riverina SA MDB

Western Central Tablelands

Oct 2018 79 89 96 100 89 91 75 39 100

Nov 2018 69 78 90 98 84 78 66 31 100

Dec 2018 59 62 79 92 81 64 56 24 99

Jan 2019 57 57 76 88 82 64 56 26 99

Feb 2019 56 64 77 89 83 62 58 27 99

Mar 2019 64 71 78 92 88 66 65 30 99

Apr 2019 67 76 81 94 87 72 65 34 100

May 2019 79 88 96 99 91 96 79 63 100 Jun 2019 87 94 99 100 84 99 89 68 100 Jul 2019 85 97 100 100 79 100 91 66 100 Aug 2019 72 95 100 100 74 99 87 54 100 Sept 2019 61 90 97 100 68 94 79 42 100 Oct 2019 51 87 96 100 64 88 71 34 99

Community-based wind erosion monitoring across Australia 3

Groundcover change The groundcover change map shows widespread decline in groundcover between July 2019 and October 2019 (red colours in Figure 3), especially in the Local Land Services Western and Riverina regions. These areas had received rain in April and May and the growth of annual herbs improved groundcover temporarily. This cover is now disappearing through both animal intake and the very dry conditions. Local Land Services North West and Central West have seen the steepest decline in area below 50% groundcover since MODIS records began (Figure 4).

Figure 3 Groundcover change between June 2019 and October 2019 as determined from MODIS

Figure 4 Area (%) of NRM with more than 50% cover since October 2005 as determined from MODIS

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Central West

Mallee

Murray

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North West NSW

Riverina

SA MDB

Western

Central Tablelands

Community-based wind erosion monitoring across Australia 4

Rainfall Total rainfall figures in October 2019 were below 10mm for the majority of western NSW (Figure 5). A small area north of Bourke and areas east of a line from Moree to Deniliquin received up to 25mm.

These rainfall figures were well below the expected long-term average for the month of October; in fact, most areas were in the driest 10% of long-term rainfall records (Figure 6a). This has pushed more of western NSW into the lowest on record category on the 18-month decile map (Figure 6b).

Updates on the latest drought status across the State can be found on the Department of Primary Industries website at: Latest NSW Drought maps.

Figure 5 Rainfall totals for October 2019 (source: Bureau of Meteorology)

Figure 6 Rainfall deciles for October 2019 (a) and 1 May 2018 to 31 October 2019 (18 month - b)

Community-based wind erosion monitoring across Australia 5

VIIRS fires and satellite image Haze from smoke and dust can be very difficult to separate for our local volunteers and our instruments. That is why we go through a rigorous process to manually classify every hour measured with our instruments into either dust or smoke. The Visible Infrared Imaging Radiometer Suite (VIIRS) satellite is of great help in this process as it indicates if there are fires in the vicinity of the instruments. It detected 6380 hot spots (375m pixel with temperature anomalies) in October 2019 across the areas covered by this report (Figures 7 and 8). Most of these were in the Local Land Services North West region (Figure 8). This number is much higher than October 2018 (1837), October 2017 (1104) and October 2016 (1688), and is a sign of the ongoing very dry conditions.

Note: The number of detected hot spots does not equal the number of fires. Large fires can have multiple hot spots depending on their size as each detection pixel only covers 375m * 375m. Hot spots can also be obscured by cloud reducing the number of detections.

The satellite image from 6 October 2019 also shows a regional dust storm (red circles in Figure 7).

Figure 7 Pixels (375m) with active burning fires in October 2019 as determined from VIIRS satellite

Figure 8 Number of 375 m pixels with active burning fires between January 2016 and October 2019.

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Number of 375m pixel detected by VIIRS instrument Central Tablelands

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Mallee

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North West NSW

Riverina

SA MDB

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Community-based wind erosion monitoring across Australia 6

From the engine room Greg Ayson 01/10/1946 – 24/10/2019

It is with great sadness that we farewell Greg Ayson, one of the longest standing members of the DustWatch volunteers. Greg was a highly respected grazier at his property Bidura station north of Balranald. He, together with his wife Loraine, ran this commendable grazing property for 40 years. Greg passed away after a short illness two weeks ago. He will be sadly missed by all of us here at DustWatch and our thoughts are with his family.

Photo1 Greg Ayson and John Leys (DPIE) discussing land management at Bidura station (Photo Terry

Koen). Insert: Greg and Loraine Ayson at the ICAR (International Conference on Aeolian Research ) gala dinner in June 2016 receiving an award for over 10 years of DustWatch volunteering from John Leys (DPIE)

The DustWatch team Contact us at dustwatch@environment.nsw.gov.au Dust data supplied by the Department of Planning, Industry and Environment Rural Air Quality network. The MODIS image is courtesy of MODIS Rapid Response Project at NASA/GSFC; the VIIRS fire data is courtesy of the Fire Information for Resource Management System (FIRMS) and the rainfall maps are from the Australian Bureau of Meteorology. This project would not be possible without funding from: The National Landcare Programme, Western and Murray Local Land Services (LLS) in NSW; the NSW EPA, the Mallee and North Central CMAs in Victoria and Murray Darling Basin NRM in South Australian, CSIRO, TERN and the Australian National University. We particularly thank our many DustWatch volunteers who provide observations and help maintain the instruments.

ISSN - 2206-3161 EES2019/0010