1. UNIT - IV
REMOTE SENSING

2. CONTENT Application of remote sensing in disaster management
Flood forecasting and warning in India.
Coordination of central water commission and Indian meteorological department.
Action plan for flood forecasting and warning.

3. Remote sensing
Remote sensing is the science of obtaining information about objects or areas from a distance, typically from aircraft or satellites. OR
Remote sensing is the process of acquiring data / information about objects/substances not in direct contact with the sensor, by gathering its inputs using electromagnetic radiation or acoustical waves that emanate from the targets of interest. An aerial photograph is a common example of a remotely sensed (by camera and film, or now digital) product.

4. Introduction
The sun is a source of energy or radiation, which provides a very convenient source of energy for remote sensing. The sun's energy is either reflected, as it is for visible wavelengths, or absorbed and then reemitted, as it is for thermal infrared wavelengths.
There are two main types of remote sensing:
Passive remote sensing and
Active remote sensing.

5. Passive remote sensing
Passive sensors detect natural radiation that is emitted or reflected by the object or surrounding area being observed.
Reflected sunlight is the most Passive Active common source of radiation measured by passive sensors.
Examples of passive remote sensors include film photography, infrared, and radiometers.

6. Active remote sensing
On the other hand, emits energy in order to scan objects and areas whereupon a sensor then detects and measures the radiation that is reflected or backscattered from the target.
RADAR ( Radio Detection And Ranging) is an example of active remote sensing where the time delay between emission and return is measured, establishing the location, height, speeds and direction of an object.

8. Applications of remote sensing…
Topography and cartography - Improving digital elevation models.
Forest- monitoring the health of crops, mapping soil moisture
Hydrology- Assessing water resources from snow, rainfall and underground aquifers.
Disaster warning and assessment - Monitoring of floods and landslides, monitoring volcanic activity, assessing damage zones from natural disasters.
Planning applications - Mapping ecological zones, monitoring deforestation, monitoring urban land use.

9. Applications of remote sensing…
Meteorology - Study of atmospheric temperature, pressure, water vapour, and wind velocity.
Oceanography: Measuring sea surface temperature, mapping ocean currents, and wave energy spectra and depth sounding of coastal and ocean depths
Glaciology- Measuring ice cap volumes, ice stream velocity, and sea ice distribution. (Glacial)
Geology- Identification of rock type, mapping faults and structure.
Geodesy- Measuring the figure of the Earth and its gravity field.

10. Applications of remote sensing…
Coastal applications: Monitor shoreline changes, track sediment transport, and map coastal features. Data can be used for coastal mapping and erosion prevention.
Ocean applications: Monitor ocean circulation and current systems, measure ocean temperature and wave heights, and track sea ice. Data can be used to better understand the oceans and how to best manage ocean resources.

11. Applications of remote sensing
Natural resource management: Monitor land use, map wetlands, and chart wildlife habitats. Data can be used to minimize the damage that urban growth has on the environment and help decide how to best protect natural resources.
Hazard assessment: Track hurricanes, earthquakes, erosion, and flooding. Data can be used to assess the impacts of a natural disaster and create preparedness strategies to be used before and after a hazardous event.

12. Uses of RS for Disaster Management
FIRE
Fire detection by satellite provides a highly efficient means of detecting and eradicating forest fires without large numbers of ground-based workers
A fire detection and management system should have the following aims:
A measure of the geographical limits of the fire-front
An estimate of fire intensity
Monitoring of burnt area to look for latent fires
Mapping of burnt areas to aid restoration

13. S.E Australian Fires February 2009
NASA Earth Observatory

14. Uses of RS for Disaster Management
FLOOD
Floods are easily seen from space - particularly over very large areas. Sometimes the view of the ground can be obscured by clouds - not a problem if the flooding was due to a large storm system
GIS models allow us to estimate the risk of flooding before it happens. Monitoring by both NOAA(  National Oceanic and Atmospheric Administration's ) and Meteosat helped disaster mitigation activities in Mozambique during 2001.
A combination of both optical and radar remote sensing can provide a model for estimating likelihood of floodplain inundation

15. Uses of RS for Disaster Management
Extreme Weather
Many natural disasters result from extreme weather events such as hurricanes, typhoons and cyclones.
These meteorological phenomena are typically large-scale and can be seen from space.
Satellites allow us to track these phenomena, determine the likelihood of them affecting human population and hence undertake mitigation activities.
The role of remote sensing for support of “geoengineering” activities.

16. Hurricane Hugo in 1989

17. Uses of RS for Disaster Management
Terrorism
Following the assault on the World Trade Center in New York on september 11th in 2001, the Ikinos and NOAA satellites were used to obtain detailed images of the site affected.
Lidar radar sweeps were used to “cut through” dust and build up a picture beneath
RS data helped inform disaster management crews

19. Uses of RS for Disaster Management
Tsunami
Like coastal flooding, Tsunami events may be modelled and within a GIS.
Complex computational fluid dynamics (CFD) requires very detailed bathymetric and topographic data retrieved from remote sensing missions. Earthquakes and landslides that contribute to tsunami formation can be assessed by different remote sensing techniques.

20. Flooded AreaChurning waters retreat from the battered coast of Kalutara, Sri Lanka, after a tsunami hit coastal areas throughout the Indian Ocean on December 26, 2004. 

21. QuickBird used extensively throughout Asian Tsunami Disaster

22. QuickBird used extensively throughout Asian Tsunami Disaster

23. Uses of RS for Disaster Management
Earthquakes
The aftermath of an earthquake is clearly highly visible from space using high resolution satellites and aerial photography
Detailed image analysis can assist ground crews to locations where electrical pylons (Tower like tall structure), ruptured gas/oil pipes or urban fires require immediate attention.

24. Uses of RS for Disaster Management
Refugee Monitoring
In recent years, the advent of very high spatial resolution imagery has allowed disaster relief workers to monitor the movement of refugees both within a country or between .
Individual vehicles as well as groups of people can be tracked and their number assessed. This information can assist logistics to refugee camps……

25. CONTENT Application of remote sensing in disaster management
Flood forecasting and warning in India.
Coordination of central water commission and Indian meteorological department.
Action plan for flood forecasting and warning.

26. Classifications of various flood situations
(i)LOW FLOOD The river is said to be in “LOW FLOOD” situation at any flood forecasting sites when the water level of the river touches or crosses the warning level, but remains below the danger level of the forecasting site. (ii) MODERATE FLOOD If the water level of the river touches or crosses its danger level, but remains 0.50 m below the Highest Flood Level of the site (commonly known as “HFL”) then the flood situation is called the “MODERATE FLOOD” situation.

27. Classifications of various flood situations
(iii) HIGH FLOOD If the water level of the river at the forecasting site is below the Highest Flood Level of the forecasting site but still within 0.50m of the HFL then the flood situation is called “HIGH FLOOD” situation. In “High Flood ituations” a special “Orange Bulletin” is being issued by the Central Water Commission to the users agencies which contains the “special flood message” related to the high flood.

28. Classifications of various flood situations
(iv) UNPRECEDENTED FLOOD The flood situation is said to be “UNPRECEDENTED” when the water level of the river crosses the “HIGHEST FLOOD LEVEL” recorded at any forecasting site so far. In “Unprecedented Flood Situations” a special “Red Bulletin” is being issued by the Central Water Commission to the users agencies which contains the “special flood message” related to the unprecedented flood.