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IAPRS & SIS, Vol.34, Part 7, “Resource and Environmental Monitoring”, Hyderabad, India, 2002
SPACE TECHN OLOGY FOR SUSTAINABLE DEVELOPMENT OF DEGRADED LANDS
R. S. Dwivedi, Sreenivas Kandrika and K. V. Ramana
National Remote Sensing Agency
(Department of Space, Government of India)
Balanagar, HYDERABAD - 500 037, India
dwivedi_rs@nrsa.gov.in, s_kandrika@ yahoo.com, rvk_nrsa@sifi.com
Commission VII, WG VII/3
KEYWORDS: Waterlogging, Mining, Aquaculture, GIS, Remote Sensing
ABSTRACT:
Globally, an estimated 1964.4 million ha of land are subject to some kind of degradation. In order to restore the fertility of degraded
lands on a sustained basis, and to prevent the deterioration of fertile land, information on their nature, extent, magnitude, spatial
distribution and temporal behaviour is a pre-requisite. Realizing the potential of remote sensing technology, the National Remote Sensing
Agency, since its inception in 1974, has been using spaceborne multispectral data operationally for generating information on natural
resources and environment variables including degraded lands. The article portrays the potential of remote sensing and GIS though three
case studies addressing waterlogging, mining and aquaculture. The information, thus generated, could be used for sustainable
development of degraded lands.
1. INTRODUCTION
Land degradation is an active global process operating at various
scales and is accelerated due to over-exploitation and
indiscriminate use of natural resources. Globally, 1964.4 million
ha of land are affected by human-induced degradation (UNEP,
1993). Of this, 1,093.7 million ha are subject to soil erosion by
water, 548.3million ha to wind erosion, 239.1 million ha to
chemical deterioration, and the rest to other processes like
compaction, waterlogging, soil salinization, mining, conversion of
agricultural land into aquaculture, etc. An estimated 3,600 million
ha of land comprising of hilly regions of the humid tropics of
India, Manchuria, Korea, south-west China and Africa are under
shifting cultivation (Schlippe, 1956 and Concklin, 1957).
In India alone, out of a geographical area of 329 million ha, 150
million ha of land are affected by wind and water erosion
(Anonymous, 1976). Annually, an estimated 6000 million tonnes
of soil is lost through soil erosion by water (Das, 1985). Apart
from this, shifting cultivation, waterlogging, and salinization and /
or alkalization have affected an estimated 4.36 million ha, 6.0
million ha and 7.16 million ha of land, respectively (Anonymous,
1976). Degradation of forest land by way of deforestation and
forest fires, mining and aquaculture could lead to very serious
environmental hazards. The article focuses on the role of remote
sensing and Geographic Information System (GIS) in the
inventory of degraded lands with three case studies - one each on
waterlogging, mining and aquaculture.
2. ROLE OF REMOTE SENSING
Remote sensing by virtue of providing synoptic view at regular
intervals has been proved to be a cost-effective and efficient tool
in the delineation and mapping the spatial distribution of lands
affected by various degradational processes. The developments in
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the assessment of degraded lands that ensued following the launch
of Landsat-1, could be broadly grouped into three categories viz.
detection and delineation of individual degraded lands,
monitoring their spatial extent and modelling. Initially, during the
period from 1975 to 1981, the Landsat - MSS data with 80m
spatial resolution had been used for generating macro-level
information on degraded lands through a systematic visual
interpretation and/ or computer-assisted digital analysis approach.
With the availability of Landsat TM data with 30 m spatial
resolution and of SPOT MLA data with 20m and PAN with 10m
spatial resolution during the period 1982 to 1988, meso-level
information on degraded lands could be generated. In fact, during
this period, a nation-wide project titled "Mapping saline/alkali
soils of India” through a systematic visual interpretation of
Landsat TM false colour composite (FCC) images at 1:250,000
scale was taken up. Concurrently, pilot studies were also
conducted to study the temporal behaviour of salt-affected soils
using multi-temporal satellite data marking the second phase of
development the technology. The following sections, through case
studies, portray the potential of remote sensing in deriving
information on lands affected by waterlogging, mining and
aquaculture.
2.1. Detection of Waterlogging due to Rising Ground Water
Table
The spectral measurements made in the visible through near-IR
and shortwave infrared (SWIR) have demonstrated the potential
of deriving information on waterlogging in terms of surface
ponding, a thin film of water on the surface and surface wetness
(Kalubarme et al, 1981; Wallace et al, 1993; National Remote
Sensing Agency, 1995, 1997). Though such measurements
provided the information that is very crucial for taking up
appropriate preventive and curative measures, the issue of
waterlogging due to rising ground water table, being a sub-surface