ekhar 
[ndia 
ty (surface and 
. activity/needs. 
as assessed by 
1 data in a GIS 
>s, the thematic 
GIS package. 
o arrive at the 
| the correlation 
rrelation exists. 
y the suitability 
) most suitable 
ops etc. Land 
that 92% of the 
ble for dryland 
in effective tool 
udy and several 
vere integrated 
| methods. The 
vas used in the 
EA 
Aur taluk (432 
carnataka State, 
N 12° 48'2" to 
75° 48'22" to 
cultural land is 
rops grown are 
Pulses (Census 
tant commercial 
loffee, Potato, 
e, Cotton, etc. 
/ery poor in this 
tivity depends 
| receives good 
errain runoff is 
; around 100 cm 
ation is around 
h almost equal 
|. The location 
3. DATA BASE GENERATION 
The Alur data base consists of 
various thematic maps (on 1:50,000 scale) 
such as ground water potential zone, soils, 
land use, wasteland, village boundaries, 
contour map, etc. (Table-1). Data were 
digitized using CALCOMP and BENSON 
digitizers and later converted into 
ARC/INFO format. All the data were 
edited, rectified, transformed and labelled, 
thus final data was made ready for analysis. 
4. METHODOLOGY 
In any given area, the slope, soil, 
water (ground and surface water), rainfall 
and climate decide the land suitability for 
any purpose, although human activity/ 
needs plays a significant role (FAO, 1976). 
To evaluate the land suitability a 
theoretically simple model is best because it 
is possible to make use of the planner's 
knowledge while evaluation. Accordingly, 
the ranking/weights method is believed to 
be one of the best models and therefore was 
applied to evaluate the suitability of land 
for various  crops/plantation (Hiroshi, 
1988). Therefore, the same method with 
two approach has been adopted. In the first 
approach slope, soil and ground water were 
integrated to arrive at the suitability. The 
suitability map thus obtained was correlated 
with the land use map. Further, land use 
map was integrated with suitability map to 
refine/modify the suitability classes. It may 
be noted that average rainfall in the study 
area is around 100 cm annually and the data 
available is for the whole taluk, since there 
is no variation within the study area this 
layer was not used for integration. 
Climatically also there are no significant 
changes, hence, not considered while 
integrating. 
The weights were assigned to 
different classes of soil, slope, ground 
water and land use maps based on their 
suitability for cultivating different crops. 
In each natural resources theme, the 
suitability of that particular class was 
assessed and weights were assigned; the 
highest weight was assigned to the class 
which is highly suitable for cultivation and 
least value for least suitable class (Table-2). 
Weights were assigned in the following 
Scale: 0 - Unsuitable; 1 - Least suitable; 2 - 
Less suitable; 3 - Suitable; 4 - More 
101 
suitable and 5 - Most suitable. In number 
of studies initially weights were assigned to 
classes of each layer, then these weights 
were subjected to statistical analysis and 
modified weights is obtained for that 
particular class (Hiroshi, 1988; Mukund, 
1991). However these exercise have 
improved the overall impact marginally 
hence the authors adopted simple weights 
method only. 
After assigning the weights, soil, 
ground water, slope and  lineament 
(fracture) maps were integrated. Thus a 
layer with basic information for assessing 
the land suitability for cultivation was made 
available. The resultant map (from ground 
water, soil, slope and fractures, termed as, 
GSSL) consists of a number of polygons, 
where each polygon has a soil, slope and 
ground water weights. These weights were 
added (cumulative) as well as multiplied, to 
generate two separate suitability layers 
named as SUMGRP and MULTGRP 
respectively. These were further grouped 
into different suitability classes such as 1 - 
Highly suitable; 2 - Most suitable; 3 - More 
suitable; 4 - Suitable; 5 - Less suitable; 6 - 
Least suitable and 7 - Unsuitable. 
In the case of cumulative weights, 
the weights of each layer in a polygon were 
added to get the total weight of that 
particular polygon. These were regrouped 
into 7 groups i.e. from unsuitable to highly 
suitable group. (Group) ah (where n is the 
total number of groups considered) consists 
of polygons which have the weights varying 
from 
wt to wt, 
where E wt, is the total weight from soil, 
slope and ground water for the 'i'th level of 
suitability. That is group 1 is best land for 
cultivation and group 2 is next best, etc., 
and group 7 is not at all suitable. 
In the case of multiplication, the 
weights of each layer in a polygon were 
multiplied to get the total weights, and 
regrouped into 7 suitability classes. 
(Group) ad) consists of polygons which are 
having the weights varying from 
m wt, to m wt, , 
where, v wt. is the product of soil, slope 
and ground water weights for the 'i'th level