parameters, the use of Geographic Information
System (GIS) almost becomes a necessity for
quick derivation of the desired results (McRae
and Burnham, 1981).
GIS is an effective and reliable modern
technique for analyzing large volumes of spatial
and attribute data related to the land. GIS may
be used in various diversified fields with
varying level of sophistication and modelling
procedures (Burrough, 1986). The various
criteria required for suitability analysis of land
in a region may be effectively analyzed
simultaneously in GIS and new information
may be generated. Keeping this in view, it is
planned to develop a GIS based methodology
for land suitability analysis for agriculture for a
part of Allahabad district.
3. STUDY AREA
Bahadurpur and Phulpur blocks of Phulpur
tehsil, one of the important tehsils of Allahabad
district, India are fast developing blocks. The
updated knowledge of land suitable for
agriculture in the region will help various
planning departments and development
authorities in formulating proper regional plans.
Hence, Bahadurpur and Phulpur blocks have
been taken as the study area (Figure 1). It is
bound between 25°15' N and 25°45' N latitudes
and 81°45' E and 82°15' E longitudes.
4. GENERATION OF INTEGRATED
GEOGRAPHIC DATABASE
The generation of integrated geographic
database by properly linking both spatial and
non-spatial databases under GIS environment 1s
the first step for carrying out land suitability
analysis. The spatial database consists of
various thematic maps arranged in different
layers in a GIS. Five thematic maps have been
generated for the present work. These are (i)
Boundary map of study area, (ii) Soil type map,
(iii) Slope map (iv) Ground water potential map
and (v) Rainfall map. ARC/INFO 7.2: GIS
software package has been used (ESRI, 1997).
For the preparation of boundary map of the
study area, relevant portions of topographical
IAPRS & SIS, Vol.34, Part 7, "Resource and Environmental Monitoring", Hyderabad, India,2002
maps 63G and 63K at 1:250000 scale were
scanned at 400 dpi resolution. These maps were
registered, projected and mosaicked. The
boundary of the study area was extracted by on-
screen digitization and after removal of
digitization errors. The remaining four thematic
maps were then prepared by adopting on-screen
digitization procedure.
From the prepared thematic maps, it has been
observed that soil map of the study area consists
of five classes, namely, sandy loam, loam, silt
loam, silty clay and silt loam with strongly
alkalinity (Figure 2). The Bahadurpur block
mainly has loam soil while silt loam is the
predominant soil in Phulpur block. The silt
loam (strongly alkaline) soil is also present in
small patches in Phulpur block. The study area
falls in the medium rainfall intensity zone with
annual average rainfall being 80-120 cm.
The slope map of the study area (Figure 3)
consists of four classes, i.e., gentle (0-196), mild
(1-396), medium (3-596) and moderate (5-109).
Most of the study area falls in the gentle and
mild slope categories. There are four ground
water classes based on the yield of aquifer in
litres/second (Figure 4). These classes are very
good (750), good (25-50), moderate (12-25)
and low (x12). The non-spatial database is then
created by storing the attributes in all thematic
layers corresponding to the spatial features. The
non-spatial database provides functional
descriptors for the geographic entities. Now,
both spatial and non-spatial databases are linked
to create the integrated geographic database.
5. GIS BASED SPATIAL MODEL
The integrated geographic database generated
above has been used to develop GIS based
spatial model for land suitability analysis. The
relative weights to different classes of all
thematic layers are assigned using Analytical
Hierarchical Process (Saaty, 1980), which is
basically a scoring method for determining
relevance of one parameter over other on
importance scale with 1 to 10 indices.
