30 
kind of degradation. But according to latest estimation, 
the area under degraded land has been reported as 107 
million hectares (DAC, 1994). So far no effort has been 
made by any single organisation to map land 
degradation although estimates on the area of land 
degradation are made by different agencies in the 
country (Table 3). At National Remote Sensing Agency 
(NRSA) the salt affected soil maps of the country at 
1:250,000 scale are prepared in association with 
National Bureau of Soil Survey and Land Use Planning 
(NBSS & LUP), All India Soil and Land Use Survey 
(A1S & LUS) and state government agencies of the 
concerned states. The salt-affected soils are also being 
mapped at 1:50,000 scale on a limited extent using 
satellite data. The soil degradation map of India at 1:4.4 
million scale prepared following GLASOD methodology 
was published by NBSS & LUP. AIS & LUS has 
initiated land degradation mapping using remote sensing 
techniques at 1:50,000 scale during 1993-94 under the 
scheme of “Application of Remote Sensing for soil 
survey and land use planning”. 
STATE OF THE ART : REMOTE SENSING 
TECHNOLOGY FOR SOIL AND LAND 
DEGRADATION MAPPING 
Though conventional soil surveys were providing 
information on soils they are subjective, time consuming 
and laborious. Remote sensing techniques have 
significantly contributed speeding up conventional soil 
survey programmes. In conventional approach 
approximately 80% of total work requires extensive field 
traverses in identification of soil types and mapping their 
boundaries and 20% in studying soil profiles, 
topographical features and for other works. In the case 
of soil surveys with aerial photographs or satellite data 
considerable field work with respect to locating soil 
types and boundaries is reduced and limited field 
observations are needed to be made. Remote sensing 
techniques have reduced field work to a considerable 
extent and soil boundaries are more precisely delineated 
than in conventional methods. Table 4 shows a 
comparative analysis of soil resources mapping at 
1:50,000 scale through remote sensing and conventional 
approaches. 
Application of remote sensing data from satellites 
for soil studies began with the launch of Landsat-1 in 
1972. Initially, the satellite data both in image and 
digital formats are utilised for preparing small scale soil 
resource maps showing soil subgroups and their 
association (Mirajkar and Srinivasan, 1975; NRSA 
1976, 1978, 1979 and 1981). In subsequent years, 
remote sensing applications for the study on soils and 
land degradation have increased. Survey of literature 
reveals that remote sensing data from Landsat MSS were 
used for mapping soils (Venkatratnam, 1984; NRSA and 
AIS & LUS 1986); and degraded lands like eroded lands 
Table 1. Soil Resources Mapping - Levels of Intensity, Classification. 
SI. 
No. 
Type/Level of 
Survey 
Basic 
Mapping 
Unit (ha) 
Scale of 
mapping 
Mapping Base 
Level of mapping 
Level of planning 
operation 
1. 
National Level 
2500 
1:1,000,000 
Satellite imagery/ 
Toposheets 
Associations of great 
groups 
National Level 
planning, IGBP 
2. 
State Level 
160 
1:250,000 
Satellite imagery/ 
Toposheets 
Association of sub 
group/families 
State/regional level 
planning 
3. 
Reconnaissance 
5.0-10.0 
1:50,000 
Satellite imagery/Aerial 
photos/Toposheets 
Associations of series 
Macro-level district/ 
sub-catchment 
4. 
Semi-detailed 
1.0-1.5 
1:20,000/ 
25,000 
Satellite imagery/Aerial 
photos/Toposheets 
Association of series 
Macro-level district/ 
taluk/watersheds 
5. 
Detailed 
0.25-0.5 
1:4,000/ 
15,000 
Satellite imagery/ 
Cadastral maps/aerial 
photographs 
Series and phases 
Macro-level village/ 
sub-watersheds 
6. 
Project 
execution 
0.01-0.10 
1:2,000/ 
4,000 
Enlarged cadastral maps 
or plane table maps 
Phases of series 
Micro-level/farm level