BackEconomic Survey uses satellite images, data to showcase development
The most striking of such maps are those of night-time luminosity, are essentially photographs of the earth at night
PremiumA little-known but growing trend of using satellite data by policymakers in India has been highlighted in the Economic Survey 2021-22, underscoring the leaps in technology usage to draft policies and track longer-term socio-economic trends.
Policymakers have used various methods ranging from night-time luminosity to the spread of urbanization to the increase in bank branches to highlight such trends.
Globally, the use of such satellite data for policymaking and research has been increasing, as the survey itself pointed out. The increasing availability of such data has largely driven this.
The pioneer in this space has been the NASA Landsat missions, which have made such data available online and for free, giving researchers and policymakers easy access to real-time data. This was followed by the European Space Agency’s Sentinel missions, and closer to home, the Indian Space Research Organisation’s own family of satellites such as Resourcesat.
The extraordinary flexibility and range of the types of data available from satellites is because of the way various substances and materials such as a standing crop of wheat, a concrete building or a polluted water body reflect light in some parts of the electromagnetic spectrum while absorbing light in others. Satellite sensors can detect these differences, some of which are outside the visible light spectrum range, and this data can be synthesized and mapped, sometimes with a lag of a few hours to a few days.
Perhaps, the most striking of such maps are those of night-time luminosity. These are essentially photographs of the earth at night, which show areas of human habitation as brightly-lit specks caused by electric lights against a dark background. These maps are more than just a pretty picture. They enable researchers to track the spread of urbanization and human settlement and are essential tools to enable updated estimates of population density over time.
Related to this are land-use maps, which can differentiate between areas of the earth covered by forests, crops and water bodies from those covered by human settlements such as buildings. Such data helps municipalities track the spread of urbanization and the conversion of agricultural land to urban uses.
A third use case is in agriculture. Satellite data can allow governments to track the progress of crop sowing through the agricultural season. Comparing the progress of such sowing in a particular crop season with those in earlier years can allow governments to detect and predict a potential slowdown in agricultural growth.
Another use case is the tracking of natural disasters such as flooding. The near real-time availability of satellite data can allow governments, NGOs and volunteers on the ground to track the spread of flooding or wildfires and plan the delivery of relief supplies to affected populations.
A fifth use case is pollution tracking. Because a more polluted water body reflects light differently than a less-polluted water body; these differences can be identified and can enable pollution agencies to locate areas of a waterbody that are less or more polluted. Similarly, air pollution and the density of particulate matter, too, can be tracked daily. While ground-level sensors can provide a picture of pollution levels at the scale of a city or neighbourhood, satellite data can track pollution levels at the scale of whole countries. A significant application of the satellite data is to identify locations where crop burning occurs during the winter months—a major source of air pollution in north India.
However, even satellite data can often not be used in its raw form—it needs to be processed by the end-user to get useful insights. “It’s easy to get satellite imagery, but the true test is to be able to build the right algorithm for policy insights," said Laveesh Bhandari, president of Indicus Foundation. He founded Indicus Analytics, a New Delhi-based economics researcher, which uses satellite data for analysis.
India does have the infrastructure to build such algorithms, said Bhandari. “But the government has focused too much on the imagery and not enough on the modelling".
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