Community-based wind erosion monitoring across Australia 1

DustWatch Report November 2019 Dust activity Dustiest month on record since records began in 2005 Wind strength Much windier than expected for the month of November Groundcover Declining rapidly across western New South Wales Rainfall Some welcome rain around Bourke; dry elsewhere Land management Drought management

Dust activity November 2019 was the dustiest month since our records began in July 2005. Prior to this drought, the highest value recorded across our long-term stations was 33 hours of elevated dust in September 2009. We averaged 94 hours across the same stations in November 2019. Ivanhoe topped the state with 215 hours of dust (Figure 1), closely followed by Walgett (212 hours) and White Cliffs (201 hours). That is close to one-third of the total hours in November (720 hours).

November 2019 had almost double the hours of strong winds (>40 km/h) than expected for the month of November across our network, partly explaining the increased values. A further reduction in groundcover across the Natural Resource Management areas covered by this report is the other reason for the increase in dust level.

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 November 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 further declined across the Natural Resource Management (NRM) areas covered by this report. Only 26% of the Local Land Services Western area has more than 50% groundcover, which is the amount of cover required to prevent dust storms. A further decline in groundcover is expected if the dry conditions continue into summer.

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

Table 1 Percentage of each NRM with cover >50% for November 2018 to November 2019 Date Central

West Mallee Murray North

Central North West

Riverina SA MDB

Western Central Tablelands

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 Nov 2019 42 80 90 99 55 76 63 26 98

Community-based wind erosion monitoring across Australia 3

Groundcover change The groundcover change map shows widespread decline in groundcover between July 2019 and November 2019 (red and orange colours in Figure 3), especially in the Local Land Services Riverina and Western regions. Some of the areas further south had good groundcover (green colours in Figure 2) and are showing a typical decline for the end of spring, whereas areas further north had already been below 50% cover and are declining further. This is increasing the risk and intensity of dust storms.

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

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

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Community-based wind erosion monitoring across Australia 4

Rainfall Some welcome rainfall was recorded in the gauges in central NSW in November 2019, with the area around Bourke, to the south of Cobar and to the north of Wagga Wagga receiving in excess of 100 mm (Figure 5).

These good falls were in the wettest 10% of long-term rainfall records (blue colours in Figure 6a) around Bourke, nevertheless, they did little to change the 18-month decile map of New South Wales (Figure 6b) with most of the state remaining in the driest 10% of rainfall records.

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 November 2019 (source: Bureau of Meteorology)

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

Community-based wind erosion monitoring across Australia 5

VIIRS fires and satellite image The satellite image for 7 November 2019 below is a good example of a day where dust (red circle in Figure 7) and smoke (green circle) from different source areas mixed at the coast, creating hazardous air quality. Haze from smoke and dust can be very difficult to separate for our local volunteers and our instruments. That is why we manually classify every hour measured into either dust or smoke. Satellite imagery is of great help in this process as it shows fires in the vicinity of the instruments. It detected 10,801 hot spots (375m pixel with temperature anomalies) in November 2019 across the areas covered by this report (Figures 7 and 8). This number is almost 10 times higher than November 2018 (1455), November 2017 (989) and November 2016 (813), 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.

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

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

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Community-based wind erosion monitoring across Australia 6

From the engine room Some Rural Network instrumentation that will replace aging instruments across the network has been temporarily diverted to provide emergency air quality monitoring in areas impacted by the devastating bushfires along the coast.

There are now three sites established along the north coast in Grafton, Taree and Coffs Harbour, and more recently two sites along the south coast in Ulladulla and Batemans Bay.

These sites are expected to remain in place until the fires are extinguished.

Real time data from the emergency monitoring sites is at Rural air quality network – live data

Photo 1 Ulladulla monitoring site – emergency smoke monitoring

The next DustWatch report is not due until mid-January. We wish all our readers and supporters a Merry Christmas and a Happy New Year.

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 EES2019/0011