September 2017

Dust activity Increased dust in the north west of NSW Wind strength Strongest winds for September for the last 12 years Groundcover Reducing in the west Rainfall Driest September for NSW on BoM records Land management Some crop failures due to extremely dry conditions Dust activity The extremely dry and hot conditions in September 2017 led to a further reduction in groundcover, especially in the north west of (Figure 4). Wilcannia, in the north west of the state set a new September temperature record of 40.5°C on 23 September 2017; only to be broken four days later by the Wanaaring Post Office recording 41.4 °C. The extreme temperatures were caused by a sequence of surface and mid-level troughs that also caused very strong north westerly winds. For details see http://www.bom.gov.au/climate/current/statement_archives.shtml. Winds transported smoke from massive bush fires in the north of the Northern Territory and Western across the (Figure 2). Strong winds also caused a substantial dust event in western New South Wales (Photo 1). Later that day the smoke and dust combined with urban air pollution leading to health alerts along the NSW east coast. This day is an example of how smoke and dust particles from diverse sources can combine and cause air quality standards to be exceeded.

Figure 1: Hours of dust activity (number in brackets) at each DustWatch site in September 2017 Community-based wind erosion monitoring across Australia 1

Figure 2: MODIS Terra image showing WA fires and smoke plumes on 23 September 2017

Photo 1: Dust storm near Wilcannia on 23 September 2017 (Credit: Ayala McFarland / @kangacamping) Community-based wind erosion monitoring across Australia 2

Groundcover Groundcover in north western New South Wales has decreased further with larger areas showing groundcover below 50% (red and yellow colours in Figure 3). In particular the Bullo Overflow east of Tibooburra and river corridor along the Darling downstream of Bourke and the area to the north west of Broken Hill and White Cliffs are now showing groundcover below 50%.

Figure 3: Groundcover for September 2017 as determined from MODIS by CSIRO. Table 1: Percent NRM area with groundcover >50% for September 2016 to September 2017 as determined from MODIS. Date Central Mallee Murray North North SA MDB Western Central West Central West Tablelands Sep 2016 100 99 100 100 99 100 98 91 100 Oct 2016 99 99 100 100 99 99 96 83 100 Nov 2016 99 98 99 100 99 99 92 78 100 Dec 2016 99 96 100 100 99 99 88 70 100 Jan 2017 99 93 100 100 99 99 86 72 100 Feb 2017 99 90 100 99 99 98 88 71 100 Mar 2017 99 95 100 100 99 99 91 77 100 Apr 2017 98 95 99 100 98 98 94 79 100 May 2017 99 97 100 100 98 99 98 86 100 Jun 2017 99 98 100 100 97 99 99 85 100 Jul 2017 99 99 100 100 98 100 99 81 100 Aug 2017 99 100 100 100 98 100 98 73 100 Sep 2017 99 100 100 100 97 100 97 76 100

Community-based wind erosion monitoring across Australia 3

Groundcover change There are three distinct areas of groundcover reduction (Figure 4), all caused by the extremely dry conditions:

1. The Bulloo Overflow east of Tibooburra

2. The Lower Darling Plains along the Darling river downstream of Bourke

3. The Eyre-Frome Plains east and north of Moolawatana.

Figure 4: Groundcover change between June 2017 and September 2017 as determined from MODIS.

100

Central West Mallee 75 Murray North Central North West Riverina 50 SA MDB Western

Area Area above 50% groundcover (%) Central Tablelands

25 Sep 2013 Mar 2014 Sep 2014 Mar 2015 Sep 2015 Mar 2016 Sep 2016 Mar 2017 Sep 2017 Figure 5: Area above 50% cover for selected NRM areas as determined from MODIS.

Community-based wind erosion monitoring across Australia 4

Rainfall Apart from some better falls up to 50mm east of Wagga Wagga and , most of New South Wales had very little or no rain at all in September 2017 (Figure 6). In fact, September 2017 was the driest September in the 110 year BoM record for New South Wales (Figure 7a). The three-monthly deciles map is not looking much better showing most of New South Wales in much below average rainfall for the last three months. This combined with the extremely hot temperatures has led to very low soil moisture levels across the state.

Figure 6: Rainfall totals for September 2017

Figure 7: Rainfall deciles for September 2017 (a) and 1 July 2017 to 30 September 2017 (b)

Community-based wind erosion monitoring across Australia 5

VIIRS fires and MODIS satellite image The number of 375 m pixels with fire during September 2017 continued to be elevated compared to last year. Local Land Services Central West and North West in particular had very high fire numbers with 1398 (52 in September 2016) and 1064 (108 in September 2016) individual fires detected.

Figure 8: Active burning fires in September 2017 as determined from VIIRS satellite.

Number of 375 m pixel with fire detected by VIIRS instrument Central Tablelands 6000 Central West 5000 Mallee 4000 Murray

3000 North Central 2000 North West NSW 1000 Riverina 0 SA MDB Jul-16 Jul-17 Jan-16 Jan-17

Jun-16 Jun-17 Western Oct-16 Apr-16 Apr-17 Feb-16 Sep-16 Feb-17 Sep-17 Dec-16 Aug-16 Aug-17 Nov-16 Mar-16 Mar-17 May-16 May-17 Figure 9: Number of 375 m pixels with fire by month as determined from VIIRS satellite. The DustWatch team Contact us at [email protected] The VIIRS image is courtesy of MODIS Rapid Response Project at NASA/GSFC; the 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, Riverina, Western, Central West, Central Tablelands 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 and in-kind contributions from Griffith University in Queensland, 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 OEH 2017/0010

Community-based wind erosion monitoring across Australia 6