Remote Sensing

"Remote Sensing"

can be defined as obtaining information about an object by observing it from a distance and without coming to actual contact with it. Infact when we see an object and understand what it is, our eye is sensing that object remotely. This is a broad definition. But we generally use this term for observing the surface of Earth from space using satellites.

The orbit of a satellite used for remote sensing is such that the satellite passes over a particular latitude at approximately the same local time. In other words, the position of the Sun with respect to a point on the Earth remains approximately the same as the satellite passes over it. Such orbits are called Sun-Synchronous orbits. These are different from Geostationary orbits.

A remote sensing satellite takes photographs of a particular region with nearly the same illumination every time it passes through that region. The most useful of remote-sensing technology is that it makes possible the repetitive surveys of vast areas in a very short time, even if the areas are inaccessible.

Space-based remote sensing is a new technology. It has high potential for applications in nearly all aspects of resource management.

India recognized the potential of this technology quite early. India conducted several remote sensing experiments in the late '60s and '70s using airborne sensors and receiving data from the US Landsat.

The experimental Earth observation satellites of India, Bhaskara-I and Bhaskara-II were launched in the beginning of the '80s. These further helped in the advancement of remote sensing in the country.

To-day, India is in the forefront in terms of building the world's best Indian Remote Sensing satellites like IRS-IC and IRS-ID. India is also in the forefront in the application of the data received from these satellites in the following important fields.

(i) Agriculture

(ii) Forestry

(iii) Water harvesting

(iv) Mineral prospecting

(v) Urban planning

(vi) Land use

(vii) Land cover planning

India has also taken up the Integrated Mission for Sustainable Development (IMSD). It makes use of spaced-based remote sensing data along with socio-economic data.

Some important remote sensing applications are listed below:

(1) In Geology: Geology has a long history of remote sensing applications. The existing, geological maps have been updated.

(2) In Agriculture: Remote sensing provides important data for crop identification and area measurement under different types of crops. The total area under cotton crop has been effectively estimated using remote sensing. Remote sensing can help raise the productivity of food grains.

(3) In Forestry: Remote sensing helps in providing information about the extent of forest cover. It also gives a general idea of the types of forest cover. It also helps in the detection of forest hazards like fire, disease and excessive felling. It also helps in biomass and fuel- wood assessments.

(4) In Land use mapping: Remote sensing data can be used to great advantage in up-to- date land use pattern of large areas at any given time. The changes that occur from time to time can also be monitored.

(5) Remote sensing can also provide data related to ocean and coastal zones:

The potential area of fish concentration can be identified. Environmental degradation that takes place in coastal zones due to overexploitation can also be monitored.

(6) Remote sensing has become a valuable tool in monitoring environmental conditions:

As an illustration, the impact of mining activities on environment could not have been known without the help of remote sensing.

(7) Satellite-based remote sensing has helped to capture details of the Earth's surface to understand the distribution and status of biodiversity.

(8) Remote sensing helps us in planning pipeline routes, ring roads and urban settlements.

(9) Flood damage assessment:

Remote sensing techniques have been found to be highly promising in flood damage assessment. This can be carried out within a week of the occurrence.

(10) Cities are fast becoming overcrowded, necessitating a planned and regular urban growth. For this, we require a data-gathering system to map and monitor the urban sprawl. Remote sensing offers excellent possibilities in solving this problem.

(11) A specialized application of remote sensing is in the field of defense, both for gathering intelligence information and for spying.

(12) Wastelands can be mapped through remote sensing. This helps us to take informed decisions on undertaking village-level development activities related to wastelands.

(13) Remote sensing satellite information helps to minimize losses in times of natural calamities by early warning systems.

(14) Remote sensing helps in the management of water resources.

(15) Remote sensing is playing a pivotal role in the fisheries sector.

(16) Drought conditions can be monitored using data obtained from satellites.

(17) Remote sensing can be used to promote tourism by identifying places of interest and minimizing environmental damage. This would help the cause of tourism industry in a big way.

(18) Remote sensing helps in the management of ground water.