Risk Wise

[

] 180

Flood damage statistics – such as the length of rail, roads, or extent

of crop area under submergence – are also transmitted to the deci-

sion makers. The spatial inundation map, along with estimates on

submergence, is generated within eight to ten hours of receiving

satellite data and disseminated to the Ministry of Home Affairs, the

Central Water Commission and State Relief Commissioners through

electronic means for further use in relief and rescue operations. There

is also a systematic feedback mechanism, through which decision

makers are able to interact with the DSC to get the required value

addition to the information.

Through the analysis of historic satellite images, a flood frequency

map is prepared showing the frequency of flooding and the extent of

inundation. Based on these maps, flood hazard zones are delineated

and updated under each river system. Flood hazard zones indicate

vulnerability and risk, and hence are useful in evolving long-term

structural and management measures for risk reduction. The infor-

mation on river configuration changes, riverbank erosion/deposition,

and the status of flood control structures is generated periodically

using multi-temporal and multi-resolution satellite data.

This infor-

mation plays a vital role in designing structural flood mitigation

measures.

Timely dissemination of information to user departments is

achieved through a dedicated satellite-based communication

network. This network operates on an extended C-band onboard

INSAT system and has facilities like video conferencing, voice over

Internet protocol and large-volume data transfer. It is connected with

state disaster emergency operation centres and key government

offices across the country that are engaged in disaster management

and knowledge institutions.

There are also plans to generate finer resolution digital

elevation maps from Airborne Laser Terrain Mapper

(ALTM) instruments, which are useful for accurately

assessing the depth of flooding – a crucial input for

flood risk assessment. The proposed launch of state-of-

the-art indigenous microwave satellite RISAT, in the year

2009, will further boost the use of space images for

disaster management.

Agricultural drought

Agricultural drought assessment using space technology

has been operational in India since 1989 through the

project National Agricultural Drought Assessment and

Monitoring System (NADAMS). NADAMS provides near-

real-time information on prevalence, severity level and

persistence of agricultural drought at state/district/sub-

district level. Currently, the project covers 13 states of

India. Coarse resolution data from AVHRR is being used

for drought assessment at regional and district level.

Moderate resolution data from Advanced Wide Field

Sensor (AWiFS) and Wide Field Sensor (WiFS) from

Indian remote sensing satellites is used for detailed assess-

ment of agricultural drought at sub-district level in four

states.

The satellite-derived Normalized Difference

Vegetation Index (NDVI) and other biophysical para-

meters are integrated with ground data on soils,

irrigation, rainfall and crop areas for assessing the agri-

cultural drought situation. During June to August,

Agricultural drought assessment

Left: NOAA AVHRR NDVI September 2007; Right: Drought intensity

Source: NADAMS drought reports of 2007, NRSA, India