JAPRS & SIS, Vol.34, Part 7, “Resource and Environmental Monitoring”, Hyderabad, India, 2002
Table-6 Area statistics salt affected soils of different states
In India
(based on 1986/87 satellite data with adequate field checks)
S.No. State Area (in
Lakh Ha.)
01. Andhra Pradesh 2.74
02. Andaman & Nicobar Islands 0.77
03. Bihar 1.53
04. Gujarat 22.25
05. Haryana 2.32
06 Karnataka 1.50
07. Kerala 0.20
08. Madhya Pradesh 1.40
09. Maharashtra 6.07
10. Orissa 1.47
li. Punjab 1.52
12. Rajasthan 3.75
13, Tamilnadu 3.68
14. Uttar Pradesh 13.68
18. West Bengal 4.41
Total 67.27
Remote sensing and GIS techniques are employed for
prioritization watersheds in the treatment of catchment of major
river systems in India. (Sharada et al, 1993; AISLUS, 2002).
The important parameters considered for prioritization of
watersheds are physiography, slope, soil properties like texture,
depth etc, land use/land cover, soil erodibility and existing
soil conservation measures.
Figure-3 IRS-LSS-IIT FCC showing ravines along Yamuna
river in part of Indo-Gangetic plains in India.
6.3 Shifting cultivation
Shifting Cultivation or jhuming is an age old practice of
primitive agriculture practiced by tribals which consists of slash
and burning of forests by tribals who cultivate these areas till
soil productivity declines and then move over to new sites.
Shifting cultivation results in rapid surface run off, enhances
soil erosion, siltation of downstream reservoirs and
environmental degradation . According to Huck (1973) and
FAO (1982) shifting cultivation is prevalent in 36 million
hectares world wide, especially in humid tropics hilly regions
of India, China, South America, South Asia, Korea and Africa.
In India shifting cultivation is practiced in about 4.36 M ha and
predominant in Northeastern states of Arunachal Pradesh,
Assam, Tripura, Manipur, Meghalaya, Mizoram, Nagaland and
690
to a lesser extent in states like Andhra Pradesh, Orissa etc. By
virtue of synoptic coverage of large areas in the narrow and
discrete spectral bands of the electromagnetic spectrum by
space borne sensors, remotely sensed data holds good promise
for mapping and monitoring shifting cultivation areas in time
and cost-effective manner.
The potential of satellite data in this respect was demonstrated
in India and a number of studies on mapping and monitoring
shifting cultivation areas using multispectral data were carried
from 1976 onwards using both visual and digital techniques.
Roy et al., (1991) through interpretation of satellite imageries
estimated that about 2.7 m ha of land in Northeastern states are
under shifting cultivation. Dwivedi and Ravisankar (1991)
using Landsat MSS data of 1978 and 1984 mapped and
monitored the shifting cultivation areas (figure-3) in parts of
Mizoram state in North Eastern India. The area under shifting
cultivation increased from 775 ha in 1978 to 1526 ha in 1984.
Further, Dwivedi et al., (1992) demonstrated the potential of
remotely sensed data in the study of stages of shifting
cultivation, role of image scale on delineation of jhum lands
and monitoring of jhum lands in parts of Tripura. Since,
shifting cultivation is dynamic, it needs to be monitored on
regular time intervals of 2 years using satellite data to see its
impact on land degradation. GIS can be effectively employed in
creating data base, updating, monitoring areas under jhuming
and to develop plans for soil conservation.
Figure-4 Landsat-TM FCC of part of Tripura state, India
showing jhum lands (bright white, small irregular patches in the
background of red colour - forest vegetation)
6.4 Waterlogging
An estimated area of 2.46 million ha land is suffering from
water logging in irrigation commands in India (Anonymous,
1991). “An area is said to be waterlogged when the water table
rises to an extent that soil pores in the root zone of a crop
become saturated, resulting in restriction of normal circulation
of the air, decline in the level of oxygen and increase in the
level of carbon dioxide”. Waterlogging may be due to surface
ponding or rise in ground water table owing to excess rain or
over irrigation and congestion of drainage. It may result in
various types of soil degradation like physical degradation or
chemical degradation or salinity. The effect of high water table
