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IAPRS & SIS, Vol.34, Part 7, “Resource and Environmental Monitoring", Hyderabad, India, 2002
4. DATA USED
In this study the data used consists of satellite data, ancillary
information and topographical maps of Survey of India.
Remotely sensed data in the form of FCC (false colour
composite) prints at 1:50,000 scale, from IRS-IB LISS-II
sensors — A1, A2, B1 and B2 of 26" February 1993 (figure-2)
were used to map soils and land use of the study area through
visual interpretation technique and ground information. Survey
of India topographical maps and published data were used as
ancillary information. The soil and land use maps were
prepared at 1:50,000 scale. ARC / INFO GIS package was used
to create database and for computation of land productivity and
for generation of outputs
Figure-1 IRS-IB LISS FCC of part of Paderu mandal
Visakapatnam district of Andhra Pradesh State, India
5. METHODOLOGY
The methodology adopted for the study consists of preparation
of soil and land use maps using satellite data at 1:50,000 scale
with filed observations, land productivity assessment through
parametric approach of Riquier et al.,(1970), creation of data
base in ARC / INFO GIS and integrated analysis of soil / land
cover information to arrive at land productivity of different soil
mapping units of the study area. The various steps involved at
each stage are discussed below:
5.1. Preparation of soil map
The soil map of the test site was prepared through systematic
visual interpretation of FCCs of IRS-IB LISS-II at 1:50,000
scale, systematic soil profile studies in the field, analysis of soil
samples and classification of soils as per soil taxonomy (Soil
Survey Staff, 1992). The final soil map was prepared with
appropriate legend showing the relationship between
physiography and soils in the test site. The soils were classified
at family level and their associations.
5.2 Preparation of the land use / land cover map
The FCC prints of satellite data were preliminarily interpreted
on light table based on photo-elements like tone, texture, size,
shape etc., and various land use / land cover classes were
delineated by placing a translucent film on the FCCs. The
classification scheme was adopted from manual of land use /
land cover mapping using satellite imagery (NRSA,1989).
Ground truth was collected both kharif and rabi seasons for
land use / land cover classes delineated from satellite data. The
final map was prepared by incorporating the filed observations
through cartographic work with an appropriate legend.
5.3 Land productivity assessment
The land productivity of the test site was assessed with respect
to crops, pasture and forest / tree species following a parametric
approach of Riquier et al.,(1970) where the land productivity
Index (LPI) was computed using a multiplicative model using
nine soil and site parameters namely moisture (H), drainage
factor (D), depth factor (P), texture / structure (T), base
saturation (N), soluble salt concentration (S), organic matter
content (O), mineral exchange capacity (A), and mineral
reserve (M).
LPIZHxDxPxTxNxSxOxAxM
Each of these factors is rated on a scale from 0 — 100 for crops,
pasture and forest / tree species separately and their percentages
are multiplied to arrive at LPI. The resultant LPI also lies
between 0 — 100 and is set against a scale placing the soil in one
or other five productivity classes as shown in table —1.
Table - 1 Actual — P, and Potential — P^ ratings of LPI
values for productivity classes
Actual -P Productivity LPI Range Potential — P*
class
1 Excellent 100 - 65 I
2 Good 64 — 35 II
3 Average 34 — 20 HI
4 Poor 19-8 IV
5 Extremely poor 7-0 V
GIS has potential for modeling the above land productivity
parameters through integrated analysis of multi-parameter data
that includes different spatial inputs such as -soils, land use and
other non-spatial data like soil physical and chemical
properties, Originally the model was proposed to study the
individual soil types. In the current experiment GIS tools were
used not only for calculating LPI values for soil types but also
for deriving area weighted LPI values for soil mapping units
and in the generation of Land Productivity map for the study
area. In the present study actual LPI (P), potential LPI (P^) and
coefficient of improvement for various soil mapping units were
computed for crops, pasture and forest / tree species using ‘aml’
utilities in GIS. The coefficient of improvement (C) was
computed for all the soil mapping units by taking the ratio of
Potential LPI (P’) upon Actual LPI (P).
6. RESULTS AND DISCUSSIONS
6.1 Soils resources
The soil map of the test site was prepared at 1:50,000 scale by
establishing the physiography — soil relationship. Altogether 8
major physiographic units, namely structural hills, residual
hills, piedmont, pediment, inselberg , buried pediplain, lateritic
hill, and
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