International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B7. Istanbul 2004
classification considering origin,
local factors (NRSA. 2002).
edaphic/climatic, and
Freshwater ecosystem
In the sphere of freshwater ecosystem, the information
needs are of diverse nature ranging from mere inventory
of surface waterbodies to more complex irrigation
performance, snow-melt run-off forecast, flood forecasting
and reservoir sedimentation etc. The role of EO inputs is
also manifold right from information about surface water
spread to grain size, properties and thickness of snow-
pack with the help of both optical and microwave sensors.
Globally many agencies are making use of EO data
towards their water resources application needs. India too
taking advantage of the EO data availability to answer its
application needs. Nearly 3.3 M ha of irrigated cropland is
annually monitored with moderate resolution multispectral
data for irrigation performance evaluation across 14 river
commands on an operational basis. 54,000 sq km area is
annually covered in Sutlej river basin alone for computing
and delivering the snow-melt run-off forecasts. Another
major contribution of EO data has been towards
exploration, recharge and prospecting of groundwater for
providing safe drinking water in India. It took off as an
operational programme for the entire country in a phased
manner after detailed analyses of satellite data,
generation of maps and positive feedback obtained from
users departments, and at present ten states have been
mapped with IRS-1D / P6 (LISS-III) data (NRSA, 2003).
Coastal ecosystem
In coastal ecosystem, the sustainability is dependent on
human impact on the system constituents. To broadly
outline, effects of population stress can be felt on the
spatial spread of the system itself, besides its natural
resources by means of depletion of ground water,
fisheries, mangroves; or the water quality in terms of
pollution and productivity; or its bio-diversity; or even the
global change in the long term through rise in sea level.
To address these issues, spatio-temporal information is
needed about its land use and vegetation characteristics,
its natural resources including pristine and vulnerable
resources, water quality, and biological richness (including
endemics) besides, the pressure factors like
demographics, infrastructure etc. The current EO systems
can provide majority of this information in scales ranging
from global to local. In terms of human activity,
information can be possible about either the extent of
human occupation of the coastal areas, or by virtue of his
planned actions through creation of infrastructure etc.
Remotely sensed data have been used for marine habitat
mapping, water quality monitoring, ship and ship-wake
detection, oil spill detection, red tide monitoring, and
mapping of reclamation activities. There have been
instances when the EO derived information is considered
mandatory by the law through gazette notification for the
delineation of Coastal Regulation Zone (CRZ), like in India
(Navalgund et al, 1999).
Disasters
The utility of EO data applications for disaster support is
taken up by many countries in a big way, and many such
efforts are still underway. For some of the disasters, part
of information needs is met operationally through EO
systems. Some of the contributions of EO data in different
hazards are chronicled hereunder:
Two main fields of interest can be defined for the use of
remote sensing data for flood disaster related
applications: (1) a detailed mapping approach for
production of hazard assessment maps, as input to
various hydrogeological models; and (2) a large-scale
approach that explores the flood situation within a system,
with the aim of identifying risk vulnerability through
prediction modeling etc. Microwave observations offer
new insights into quantification of hydrological variables
changing over time and space, which are very difficult to
measure on ground. Its general information needs are
land use, infrastructure status, vegetation, soil moisture,
snow pack, DEM and near-shore bathymetry during pre
and post-flood periods (CEOS). Current EO capability
includes operational services of the above parameters.
Efforts are also on to improve and develop the satellite-
derived precipitation algorithms. In India, near-real time
flood monitoring is being done, wherein, administrative
(village) and current land use layers are being overlaid in
GIS on top of satellite-based inundation layers to identify
affected settlements, damage assessment and for relief
purposes. All five flood-prone states, viz. Assam, Bihar,
Uttar Pradesh, Orissa and Andhra Pradesh are under
regular surveillance by a gamut of satellites (including
Radarsat-1) during flood season covering nearly a third of
India’s geographical area; and information is disseminated
to Relief Commissioners.
Drought is another important weather-related natural
disaster. It is aggravated by human action, since it affects
very large areas for months, even years, and thus has a
serious impact on regional food production. Information
needs related to drought are its early warning of onset,
estimation of affected area, intensity and duration, plan for
immediate relief and long-term management for drought
mitigation etc. Currently drought monitoring mechanisms
exist in most countries that use ground-based information
on drought related parameters such as rainfall, weather,
and crop condition and water availability. Satellite based
EO are complimentary for the provision of synoptic, wide-
area coverage and provision of frequent information on
drought conditions. Being a semi-arid tropical country,
India too faces severe agricultural drought periodically
due to infrequent rainfall. In India, a National Agricultural
Drought Monitoring Systems (NADAMS) project gives
fortnightly information during monsoon season at district
level using satellite-derived NDVI information as input.
This is in operation for the last eighteen years.
EO data is useful in mapping landslide related factors;
characterization of landslide deposits monitoring;
preparedness (monitoring and mitigation); and response.
EO data also helps in the preparation of spatial databases
on lithology, faults, slope, vegetation and land use,
including temporal changes. In the field of type of
landslide mapping there is limitation to the operational use
of EO data. During the preparedness phase (both in terms
of monitoring, warning and prediction), EO data provides
valuable inputs to supplement the in-situ monitoring
systems by landslide hazard zonation approach. In early
warning phase, new areas of approach especially SAR
INTERFEROMETRY, GPS and ground data collection
platform are gaining importance for understanding the
movement of landslide. In the mitigation phase, high
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