International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B7. Istanbul 2004
Qualitative indicators allow to identify the specific
characteristics of landform units(s) in terms of spatial change
detection e.g. landslide/ soil erosion / flood prone areas,
bankline shifting of a river or shoreline shifting etc.
A Quantitative indicator is supplementary to Qualitative
indicator. In this context, numerical attributes related to change
detection generated from insitu measurements are of basic
importance e.g. round the year beach profiling data to specify
the zone of erosion or accretion; sediment monitoring station
may generate data on soil erosion; variation in chemical
qualities of water in identifying the hydrological characteristics
of an area.
4. GEO-ENVIRONMENTAL UNIT (GEU)
Spatial database with certain entity or bounds as defined by GEI.
A GEU may contain one or more TMU (Meijrink, 1988) or
Natural system unit (NSU) and vice-versa. For example —
i) In the Medinipore coastal plain, West Bengal, India erosion is
present in the beach face of Digha-Shankarpur (Chandpur)
sectors whereas accretional phenomenon is observed in the same
beach face of Dadanpatrabar-Junput area (Chakrabarti, 1991,
1995). In both the cases, the terrain unit is 'beach face' but two
GEU may be identified depending on erosional and accretional
behaviours. (Photo — 1)
ii) In western upland of West Bengal, India forest/ social
forestry is present in different terrain units viz. Buried pediment
(shallow) and Lateritic upland (Chakrabarti et. al, 1996, 1998,
2002). In this case, with pragmatism two different terrain units
may be clubbed under one GEU (e.g. "Forest land") giving more
emphasis on land cover/ landuse factor in comparison to other
factors like degree of dissection, slope aspects etc. which may be
considered for further subdivision in user orientation.
iii) In. Jambudwip, (a tidal shoal in the Hooghly estuary),
mangrove forest is fast deteriorating covering two TMUS (viz.
Mangrove swamp and Supratidal core) due to human
interactions (Chakrabarti, 1991). In this case 'Mangrove forest
zone' may be identified as a GEU considering the geomorphic
environment challenged by anthropogenic activities.
iv) Arsenic contamination in groundwater — Terrain analysis and
classification reveals that in western part of Bhagirathi /
Hooghly river (major distributary of Ganga river) arsenic
toxicity in groundwater prevails in the Younger alluvial plain
whereas the groundwater in the adjacent alluvial plain / fan areas
of Ajoy and Damodar river are free from arsenic contamination
(Photo-2). In geomorphological terms both are alluvial plain,
however, two GEU may be identified based on the occurrence of
arsenic contamination phenomenon.
v) In the Gondwana Upland two types of Coal mining activities
are in operation: open cast mining and underground mining. In
the context of environmental analysis three different GEU could
be delineated viz. the ‘disused’ open cast mines, mining waste
dump and areas of land subsidence (Photo-3) though
geologically / geomorphologically the area is termed as
Gondwana Group / Gondwana Upland.
428
5. APPROPRIATE TECHNOLOGY
Geo-informatics, operational combination of RS and GIS
technologies (Fig-3; Chakrabarti & Nag, 2002) play facilitator
role in collection as well as integration and analysis of the up-to-
date spatial and aspatial database with the existing data sets to
generate application specific ‘strategic datasets’ for
technological adjustment (structural means) and social
adaptations (non-structural means) with future perspective,
towards:
e Environmentally sound landuse/ landcover practices. In
Indian scenario, Agro-ecological characterization —
agricultural environment analysis and biodiversity
conservation need special attention regarding socio-
economic conditions (e.g. marginal farmers do not consider
the environmental hazard created by them in the context of
using pesticides etc. for their livelihood).
e Minimising the adverse effects of natural hazards (e.g.
droughts, floods), land degradation etc.
e "Easy to use' data format in digital mode to enable
e-governance especially in a sector like rural poverty
alleviation and food security as well as biodiversity
conservation.
In the present scenario, the state-of-art technology of the high
resolution 'operational' Earth Observing Satellites (EOS)
provides multi-temporal/ time critical up-to-date 'real world'
features in digital mode or in hard copy format. In this respect,
the RS data are playing facilitator role in collecting or detecting
spatial as well as thematic aspects of the changing earth's
surface.
In global scenario, presently, two Indian 'civilian' satellites —
IRS 1C and IRS 1D with 5.8m (PAN) and 23.5m (FCC)
resolution are leading provider of satellite data for commercial
uses and applications. Recent additions are IKONOS satellite,
which provides image of 1m resolution in PAN mode and 4.0m
resolution in FCC mode, Quick Bird with 90 cm resolution in
PAN mode and Resource Sat 1 (IRS P-6) with 5.8m resolution
in multi-spectral mode. The microwave satellites (viz. ERS,
JERS, RADARSAT etc.) with all weather and all time
capabilities facilitate the operational use of RS data for real-time
monitoring of disaster prone areas in terms of flooding, coastal
surges, landslides etc. In near future, with the introduction of
'Hyper spectral imaging' system (with more spectral bands and
narrow band widths) scope of separability of different objects/
materials will be enhanced significantly (Skidmore et.al, 1997).
In response to the 'PIXELCORASTER FORMAT inherent
relationship the RS data are being widely used in GIS
(Geographic Information System) environment for integration
and analysis of spatial and related non-spatial attributes as per
users choice.
Rational and optimal utilization of RS and GIS for
identification, integration and analysis of thematic aspects of
terrain units in relation to the generated / existing numerical
attributes (by insitu/ conventional methods) may be considered
as the most holistic approach to conclude on decision rules/
norms for GEI and GEU.
6. GEO - ENVIRONMENTAL MAPPING:
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