International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B4. Istanbul 2004 
     
  
  
  
  
  
  
  
  
270000 520000 
41700 -4170000 
3250 
3000 
$ * 2500 
:EM ww 
$ 2000 
H E 
a 
t 
EM- 1500 
1250 
1000 
750 
- 500 
4100000 4100000 
470000 520000 
Figure 3. DEM Grayscale representation 
No.Data 8756001 Minimum 500 
Mean 1261.02 | Lower Quartile 933 
Variance 241483.79 Median 1101 
Range 2980 | Upper Quartile 2763 
Interquartile range 1830| Maximum 3480 
  
  
  
  
  
Table 1. DEM Basic statistics 
3.2 Geological localization 
The study area is situated in the central sector of the Betic 
Cordillera, to the north of Sierra Nevada range. This area 
comprises most part of the Guadix basin. The Guadix basin 
overlies the contact between the Internal and the External 
Zones. This intramontane basin was established as a separate 
basin in the Late Miocene (Fernández et al., 1996; Soria et 
al., 1998) after the main tectonic movements that formed the 
large structures of the Betic Orogen. Sedimentation in the 
basin began in the Tortonian after the partial closure of the 
North-Betic Strait. The basin was filled in the Late 
Pleistocene, concurrent with the termination of the endorheic 
infilling. Since then, the entire basin area has formed part of 
the catchment area of the Guadalquivir River, and has been 
subjected to significant erosion (Calvache and Viseras, 
1997). 
3.3 Classification 
Considering the dimensions of the study area and the 
available information (and its density), a moving windows 
schema has been designed. The windows size is 
2000mx2000m (100x100 data points) and the windows 
displacement ‘is equal to 200m in both directions (10 data 
points). This schema produces 241x341 windows. 
At each window, ten descriptive statistics. have been 
calculated: mean, variance, coefficient of variation, 
minimum, lower quartile, median, upper quartile, maximum, 
range and interquartile range; and the directional variograms 
in the four main directions (NO?E, N45?E, N90°E, N135°E) 
considering 20m lag -at NO*E and N90°E directions- and 
28.284m lag —at N45°E and N135°E directions-. From the 
variogram calculations the following variables have been 
selected: y;; value for i-distance (100m, 500m, 1000m and 
1500m) at j-direction (NO°E, N45°E, N90°E and N135°E); for 
cach direction; the maximum value, the direction of 
maximum variability (maximum value) and the anisotropy 
ratio (Ry) defined as the maximum value divided by the 
minimum value. A total of 32 statistical parameters have 
been obtained for cach window. These data have been 
included in a multivariable digital terrain model (figure 4) 
that has been processed using an ISODATA non-supervised 
classification. 
  
Figure 4. Variables obtained from the statistical analysis used 
in the classification. Left: Local mean terrain height; Right: 
Local variogram values at NOE direction (distance 100m). 
3.4 Results 
A total of seven classes are obtained in the final map (figure 
5 and table 2). 
Class A (9.28% of total area): This class is related with small 
irregularities that arc present in the Guadix basin. The class 
has a mean height value of 1062m and a coefficient of 
variation around 16%. A very characteristic statistic is its 
interquartile range of 146m, that indicate what the terrain 1s 
basically a flat area with a reduced variability. The 
directional variograms suggests that phenomenon is very 
continuous and isotropic (with anisotropies ratios lower than 
1.5 for 1500m distance). This class is composed by the small 
sills presents in the Guadix basin. 
Class B (47.7994 of total area): This class is related with the 
most of the Guadix basin area. The class has a mean height 
value of 983m and a coefficient of variation around 18%. 
This is a flat area too with a interquartile range of 247m. This 
is a very continuous and isotropic area with anisotropy ratios 
lower than 1.16 in all distances. 
Class C (0.9896 of total area): This class presents a higher 
mean value than Classes A and B (1093m) and greater 
variability. has similar characteristics than Class A, but 
present a greater variability. The basic characteristic of this 
class is its anisotropy. The variability is lower in N45°E 
direction with ratios that raise around 5.8 at 1500m distance. 
This class is presented positional linked to the Class A. 
Int. 
  
No. 
Me: 
Var 
CV! 
IOR 
Low 
Mec 
  
  
  
  
  
  
E 
Y100. 
Y 100. 
Y 100, 
Y500, 
Y500. 
500. 
Ÿ500. 
Ÿ 1000 
Ÿ1000 
Ÿ1000 
  
71000 
11500 
Y1500. 
Y1500 
| Ryio 
Ry 50i 
| Ryio