effectively minimizing seasonal variability in the imagery
(Healey et al., 2005).
The purpose of the disturbance index is generally to measure
vegetation degradation that results from any number of natural
or human induced causes such as forest fires or forest-insect
infestations (Hais, et al., 2009). But, in the study area it also
exemplifies the contrast between irrigated agricultural fields and
bare ground. In our study, disturbance-index images were
generated for the dates between 1992 and 2011 and were used
to characterize spatiotemporal patterns of irrigated agricultural
fields on Harran Plain based upon the original reflectance
images—brightness, greenness and wetness (Table 2).
Table 2. Landsat imagery used for creation of the cumulative
disturbance indices.
Date Sensor
05.09.1992 Landsat TM 5
21.08.1998 Landsat TM 5
24.08.1999 Landsat TM 5
26.08.2000 Landsat TM 5
28.08.2002 Landsat ETM+
27.08.2006 Landsat TM 5
30.08.2007 Landsat TM 5
04.09.2009 Landsat TM 5
22.08.2010 Landsat TM 5
25.08.2011 Landsat TM 5
Furthermore, meteorological datasets were obtained from
Adiyaman (North of Ataturk Dam) and Sanliurfa (South of
Ataturk Dam) stations for the analysis of climate data on the
dam lake and the Harran Plain within the period of 1894 to
2011.
4. RESULTS AND DISCUSSION
During the Atatiirk Dam construction period between 1984 and
1992, spatial variations of agricultural fields and water reserve
were determined (Fig. 3). By the year 2011, it was found that
367.65 km? of the agricultural area (about 45% of the dam-lake
surface area) has been inundated. The total filling of the
reservoir results in a lake area of 800 km? (Fig. 4).
en # Water Reserve
8 Agricultural Fields
7
1984
1985 1986 1987 1990 1991 1992
Fig. 3 Spatial variations of agricultural fields and water reserve.
For the Harran Plain and the Atatürk Dam Lake, different
meteorological datasets were used. Monthly averaged values of
air temperature, humidity and rainfall observed at the Sanliurfa
and Adiyaman meteorological stations (Fig. 2) were used for
years between 1984 and 2011.
It is expected that one of the prominent difference of the
meteorological parameter between these regions is the
temperature (Fig. 5).
Fig. 4 Water reserve changes on the Atatiirk Dam Lake between
the years 1984 to 2011.
Temperature (°C)
t2
oo
—Sanliurfa Station
i —-Adiyaman Station
26 i aie
1984 1988 1992 1996 2000 2004 2008 MN
Fig. 5 Annual temperature distribution of Dam Lake and Harran
Plain Regions.
For the other part of the study, change detection is performed
using the Disturbance Index for Harran Plain in order to
characterize spatiotemporal patterns of irrigated agricultural
fields. When the Landsat time series analyses are examined, the
contrast between irrigated agricultural fields and bare ground
has been clearly seen (Fig. 6).
It ha
incre:
2011.
exp
Occ
and