wnloaded from 
d calibrated to 
ered relatively 
idation points. 
ations running 
'S. ACTOSS each 
ion cover and 
on cover was 
ssistance of a 
which a secchi 
3 points across 
then compared 
Land Monitor 
nial vegetation 
Ihe inundation 
nce to create an 
isets were then 
e 263 wetland 
culated. When 
face water in a 
/etlands which 
classified as 
than 12 times 
es, 2008). The 
l. 
for separating 
) values were 
surface water 
vith increasing 
appear in the 
sites recorded 
e surface water 
  
  
Yt surface water 
onds to point 2 
s covered with 
surface water, much of this water was covered by a stand of 
emergent halophytic vegetation. The halophytic vegetation 
covered 4096 of the site and much of the foliage was desiccated. 
This caused an increase in reflectance of Band 5. 
  
Figure 3: Inundated site with dense coverage of emergent 
halophytic vegetation. 
From visual interpretation of the regression in Figure 2 a 
threshold value of 28 was derived. To further examine the 
relationship between surface water cover and Band 5 values, 
Band 5 values were extracted along transect lines which 
intersected field sites 1, 2 and 3 (Figure 4). Photographs from 
the 3 field sites, located in Lake Logue, are shown in Figure 5. 
  
  
  
  
| 1 
100 - 
| | 
| 80 - 
| | 
jo. 604 
| 
$7] 
8 | 2 
| 40 - Not inundated 3 
| 20 inundated Mt ter tees tto 
| o eo r- © © ~~ e © D © 
<r oo e nr ER «e e < co 
| -— = a Q e e e 
| Distance (meters) | 
  
; Figure 4: Band 5 values extracted along a transect line which 
includes 3 sample points with the derived threshold value in red. 
  
Figure 5: Photographs from sites 1, 2 and 3 (left to right) at 
Lake Logue. 
The Lake Logue sites 1, 2 and 3 recorded average water depths 
of 5, 10 and 25 mm, percent water coverage of 70, 60 and 100 
and percentage vegetation cover of 50, 20 and 10 respectively. 
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 
A dramatic drop in Band 5 values was observed between sites 1 
and 2. While depth and percent water cover are marginally 
different between the 2 sites vegetation cover drops from 50 to 
20 %. 
The inundation threshold was applied to the validation image 
and checked against the 16 field sites. The overall accuracy of 
the classification was 87.5%. All errors were sites that were 
predicted to be “not inundated” but were found to be 
“inundated”. Field sites with greater than 50 % surface water 
coverage were classes as inundated. 
3.2.  Hydroperiod classification 
The criteria for a wetland to be classified as “Permanently 
inundated" is that it must be more than 10 % inundated for 70 % 
of the time (or 12 out of the 17 years assessed). Of the 263 
wetlands assessed in this study only 2 met this criterion. The 
remaining wetlands were classified as “Seasonally inundated”. 
The total area inundated across all wetlands was also assessed 
(Figure 6). Area inundated appears fairly consistent across the 
time period. The year 2000 is anomalous. This can be explained 
by the heavy winter rainfall in 1999 which helped push the total 
rainfall, at the nearby Jurien Bay weather station, for this year to 
970.8 mm. The mean annual rainfall is 536.3 mm (Bureau of 
Meteorology, 2011). 
  
Area (ha) Inundated 
  
2000 
1500 4 
Area (ha) 
S 
e 
e 
500 4 
  
  
  
  
  
0 : 
0 ONU «v DO dw O Q O' x i «o r o o © + 
OHO DIO Q OO O O oO OOo ooo SE = 
9oQ B OO 0 0 0 00 OoO0O 0 oO o oco oO o 
- = = + + + ON ON A A As Nas as a AU N 
Year 
  
Figure 6: Area of inundation per year. 
4. DISCUSSION 
Landsat band 5 was successfully used to separate not inundated 
from inundated plots. Vegetation cover was found to be the 
major confounding factor. At 2 plots, high vegetation cover and 
high surface water cover were recorded. In both cases band 5 
digital counts were significantly higher than sights with low 
vegetation cover. Furthermore, these sites could not be 
separated from vegetated sites that were not inundated. 
The reflectance of vegetation in band 5 is influenced by 
moisture content and thickness of the leaf (Lillesand & Kiefer, 
1994). Vegetation will absorb more light in Band 5 than bare 
soil and will reflect more than water. The percentage of 
vegetation cover at which band 5 reflectance increases is 
difficult to discern from this study, but it is likely to be heavily 
dependent on the type of vegetation. Both 40 96 coverage of 
woody halophytic vegetation and 70 96 coverage of lush grassy 
vegetation were sufficient to dramatically increase band 5