the irrigated land cover map (Plate 3) shows, about 25 percent
of
CGID
area was actively irrigated throughout the seasons, be-
ing designated as perennially active (e.g., perennial pastures).
Other areas were seasonally irrigated (e.g., annual pastures).
About 21 percent of the area was actively irrigated, at least in
two seasons (Table 3). A substantial proportion (42 percent) of
the area was active only in spring.
Irrigation Water Deliveries and Farms Identified as “Irrigated”
To determine whether irrigation was actually applied, temporal
records of irrigation water delivery were used. As the irrigation
records were available at farm level (irrigation license unit),
validation was possible at the same unit level. All farms that
received irrigation water deliveries were treated as “irrigated”
and others as “non-irrigated.” This was taken as the “actual”
(a)
(b)
Figure 8. The patterns of (a)
ndvi
, and (b) temperature of the selected data points classed as annual / autumn irrigated crops. Here the
temperature (
Ts − Ta
) has been scaled from 0 (minimum) to 1 (maximum) for display purposes.
(a)
(b)
Figure 9. The patterns of (a)
ndvi
, and (b) temperature of the selected data points classed as summer irrigated crops. Temperature (
Ts
− Ta
) has been scaled from 0 (minimum) to 1 (maximum).
(a)
(b)
Figure 10. The patterns of (a)
ndvi
, and (b) temperature of the selected data points classed as perennial irrigated crops. Temperature
(
Ts − Ta
) has been scaled from 0 (minimum) to 1 (maximum).
T
able
3. I
rrigated
L
and
C
over
C
lassification
of
the
C
entral
G
oulburn
I
rrigation
D
istrict
, 2012/2013
Class Description
Area (%)*
Spring Active
42
Summer Active
1
Autumn Active
2
Perennially Active
24
Perennially Active (Sec)
1
Spring – Summer Active
4
Spring & Autumn Active
16
Summer-Autumn Active
1
No Class
9
* Percentage of total farmland (1290 sq. km.)
PHOTOGRAMMETRIC ENGINEERING & REMOTE SENSING
March 2015
235
