In many countries like India, risk analysis is limited to hazard mapping, showing areas where different levels of hazard
can be expected. The available risk information is usually at too limited in spatial and temporal resolution to provide
useful information on increasingly complex and dynamic risk patterns. Risk maps, based on coarse resolution Earth
Observation (EO) data, give the impression of uniform hazard and vulnerability patterns over wide areas. As such risk
is quite complex and dynamic. Risk analysis strategies have normally been restricted to the physical aspects. In most
countries it is extremely rare to find risk analysis to take account of the social, economic, institutional and cultural
aspects of vulnerability. The absence of conceptual and spatial models capable of representing the social, economic
and cultural dimensions of vulnerability is another problem. Many aspects of vulnerability are difficult to quantify.
The development of advanced models is still at the frontier of geo-informatics research, with the result that there are
still no tried and tested procedures available for building social vulnerability aspects into risk information systems.
The present paper suggests couple of approaches wherein multi-date EO data have strategically been used for risk
assessment due to floods and drought.
Using conjunctively electro-optical and radar systems has been a part of India's Earth Observation (EO) strategy for
disaster management. To address the gaps in the operational systems of disaster management, increasingly improved
quality of information in terms of spatial scale, temporal scale and all weather capability mapping are called for and the
EO satellites have accordingly been configured. For example, CCD camera (1 km spatial resolution) in GEO orbiting
INSAT satellites, which work in conjunction with polar orbiting IRS WiFS (188 m spatial resolution) for real time
coarse observations of the events such as forest fire, floods etc is in operation. To address the subtle features associated
with agricultural drought, Resourcesat has been configured with Advanced WiFS having 55 m spatial, 5 days
repetativitity, 740 km swath and 10 bits radiometry. It is a unique mission with variety of payloads viz., AWiFS, LISS 4
(5.8 m multi-spectral; 22 days repetativitity) and PAN from the same platform. The Digital Elevation Models (DEM)
emanating from Cartosat are providing valuable inputs to characterize geo-physical terrain vulnerability. Radar Imaging
Satellite (RISAT), with all weather capability mission, is yet another mission configured for disaster management.
Taking into account the flood dynamics as well as the river basin parameters, RISAST is being configured with multiparametric
C-band SAR with 5 imaging modes; 1-2 m spatial resolution; 224 km swath; 7 days repetitivity and 8 bits
quantizations. Integrating these capabilities, space based Disaster Management Support (DMS) systems, in India, has
been built upon committing EO enabled products and services for disaster reduction on operational basis.
Despite having half a dozen operational EO missions already in the orbit, the need to have dedicated constellation of EO
satellites emanates from India's perennial vulnerability to the natural disasters. Capturing an event in real time, along
with the appropriate spatial attributes--characterizing the impacts, precursors and other inter-relations, is critically a
missing link. Potentially, a dedicated constellation of EO satellite--with suitable mix of optical and SAR payloads
captures the events in its real time form. The right choice of sensors holds the key for low cost autonomous missions
characterizing the constellation. It is visualized to have AWiFS type of camera with visible, near infrared, short wave
infrared and thermal sensors onboard GEO mission. The optical LEO missions could include LISS 3&4 type of cameras
along with C band SAR. For 'formation flying', a set of visible/infrared imagers, infrared sounders, microwave imagers,
microwave sounders, scatterometers and radar altimeters with suitable bands, data rate and resolutions assumes
significance. It has been visualized to make strategic transition of India's planned and future EO missions to a system of
thematic constellations, wherein AWiFS could move to GEO; RESOURCESAT and RISAT could converge into a LEO
constellation; OCEANSAT would lead transition into 'formation flying'. The paper intends to describe such strategies.
Conference Committee Involvement (1)
Multispectral, Hyperspectral, and Ultraspectral Remote Sensing Technology, Techniques, and Applications