8, 2012 
003; Lawrence 
| communities. 
ed Gum forest, 
Box and Grey 
MDBC, 2006; 
Department of 
.gov.au) were 
ih Forest. The 
(RGW), 
à 
W). 
getation types 
etation type in 
rest area. The 
vhich accounts 
/ South Wales 
   
Victoria 
Riverine Grassy Woodlands or Forests 
Plains Woodlands and Forests 
Wetland Associated Vegetation 
Lower Slopes or Plains Woodlands 
9 25:55 10 Km 
LL LL LLL Ld 
. Class Groups 
Landsat 5 TM 
or 27/11/1993, 
re converted to 
a 30m spatial 
Mrared | (NIR) 
(I) 
  
    
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XXXIX-B8, 2012 
XXII ISPRS Congress, 25 August — 01 September 2012, Melbourne, Australia 
Satellite-based assessments of ET were calculated according to 
Allen et al (2007b). Surface roughness of vegetation was 
estimated using the relationship of Teixeira et al (2009). 
ET data were standardised against ETr values appropriate to 
individual images, and are presented in terms of ETrF, where 
ETrF equals ET/ETr. ETrF values of near zero represent little 
or no ET, whereas values of approximately one indicate near 
maximum ET rates of ‘dry’ vegetation. ETrF values greater 
than one indicate ET rates that exceed vegetation maxima, and 
are generally associated with wet surface soil conditions or the 
presence of surface water on vegetation. 
Ground-based weather data used in the ET calculations were 
sourced from weather records archived at the Department of 
Primary Industries Tatura and www. weatherzone.com.au. 
Monthly rainfall data for Echuca were sourced from the Bureau 
of Meteorology (www.bom.gov.au). River flow information 
was sourced from the Murray Darling Basin Authority 
(hitp:/www.mdba.gov.au/water/live-river-datæ). 
3. RESULTS 
The dominant vegetation type in the Barmah Forest is RGW, 
with smaller areas of WAV, LSW and PWF present (Figure 1). 
Individual vegetation types showed a decrease in ET rates of 
between 35% and 55% between 1993 and 2008. There was a 
decline in NDVI of between 11% and 18% for individual 
vegetation types between 1993 and 2008 except for WAV, 
which increased 58% over the same period. 
Table 1. Mean (and standard deviation) NDVI and ETrF pixel 
values for vegetation types located within the 
Barmah Forest. 
  
  
  
  
  
  
  
  
  
  
  
  
  
  
Vegetation Date NDVI ETrF 
RGW 26/11/1993 0.36 (0.13) 1.10 (0.23) 
RGW 6/11/2003 0.42 (0.07) 0.71 (0.16) 
RGW 3/11/2008 0.32 (0.06) 0.61 (0.13) 
WAV 26/11/1993 0.19 (0.28) 1.28 (0.16) 
WAV 6/11/2003 0.45 (0.11) 0.89 (0.13) 
WAV 3/11/2008 0.30 (0.08) 0.57 (0.23) 
LSW 26/11/1993 0.40 (0.08) 0.95 (0.21) 
LSW 6/11/2003 0.39 (0.06) 0.59 (0.10) 
LSW 3/11/2008 0.33 (0.42) 0.55 (0.08) 
PWF 26/11/1993 0.38 (0.10) 0.84 (0.27) 
PWF 6/11/2003 0.37 (0.06) 0.57 (0.11) 
PWF 3/11/2008 0.32 (0.05) 0.55 (0.10) 
  
  
  
  
  
  
n: RGW = 306,492 pixels, WAV = 26,435 pixels, LSW = 
2,905 pixels, PWF = 8,330 pixels 
The spatial distribution of change in ET rates between 1993 and 
2007 is shown in Figure 2. Approximately 88% of the forest 
showed a decrease in ET rates. Approximately 48% of the 
forest experienced a decrease between 25% and 50%, while 
33% of the forest showed a decrease of between 1% and 25%. 
Most areas that experienced an increase in ET rates are 
associated with river channels running through the forest. 
Figure 3 shows the spatial distribution of change in vegetation 
cover (NDVI) between 1993 and 2008. Areas of increasing 
NDVI are associated with WAV in the north-west section of the 
forest, and RGW in the southern sections of the forest. 
New South Wales 
   
      
Victoria 
No change 
> 75% decrease 
75 - 50% decrease 
50 - 25% decrease 
25 - 1% decrease 
1 - 25% increase 
25 - 50% increase 
50 - 75% increase 
& > 75% increase 
N 
4 À 
0 25 5 10 Km 
Lis tte) 
Figure 2. Change in ETrF between 27/11/1993 and 3/11/2008 
New South Wales 
  
Victoria 
75 - 50% decrease 
50 - 25% decrease 
25- 1% decrease 
1- 25% increase 
25 - 50% increase 
50 - 75% increase 
> 75% increase 
  
0 :25--5 10 Km 
LLL LL Ld 
’ 
\ 
i 
Figure 3. Change in NDVI between 27/11/1993 and 3/11/2008 
Figure 4 (see next page) presents mean ET rates for the Barmah 
Forest within a time-series of average monthly river flow 
volume and monthly rainfall totals. Figure 4 shows high river 
flow levels during 1993, 1996 and 2000. An average monthly 
river flow exceeding 24,500 ML/day results in 75% to 80% of 
the forest area flooding (Dexter and Poynter, 2005; MDBC, 
2006). An average monthly river flow exceeding 18,300 
ML/day results in 35% to 50% of the forest area flooding 
(Dexter and Poynter, 2005; MDBC, 2006). Figure 4 also 
highlights the reduced river flow rates between 2001 and 2008, 
which are coincident with years of drought in the area. 
The mean annual total rainfall in the area is approximately 428 
mm. While some years received above average rainfall (1993 
(567 mm), 1995 (451 mm), 2003 (516 mm)), most years 
received below average rainfall. The lowest total recorded over 
this time frame were 2002 (189 mm) and 2996 (204 mm). 
Figure 4 also highlights monthly variability in rainfall and 
shows several key rainfall events in October 1993 (116 mm), 
November 1998 (94 mm), October 2005 (120 mm) and January 
2008 (99 mm).