Geographic information system

Also called: GIS, Geographical information system · Topic: Remote Sensing, GIS and GNSS · NCERT: Class 11, Ch 1 "Geography as a Discipline"; Class 12, Ch 4 "Spatial Information Technology"

Meaning

A geographic information system (GIS) is a computer system for capturing, storing, checking, integrating (combining), manipulating, analysing and displaying data that are spatially referenced, which means each piece of data is linked to a real place on the earth.

It matters because it joins location with analysis. A planner can ask not only what is where, but also why it is there and what if it changes. Class 11 Geography as a Discipline notes that GIS and GPS have widened the scope of geography. Geography moved from describing places to measuring them, modelling them and planning for them.

Explanation

Why GIS was needed and how it works

• Older computer tools could only do half the job:
• A database management system (DBMS) is software that keeps data in tables of rows and columns, such as a register of village names and populations. It knows "what" but not "where".

• Computer-assisted cartography draws maps on a computer. It knows "where" but cannot work out "why" or "what if".

• GIS joins the two:

• Each feature on the map, such as the boundary of a state, is linked to its descriptive data, such as its literacy rate.

• Because the two are linked, the computer can search, compare and combine them.

• When it became possible: from the mid-1970s, when computers became powerful enough to handle maps and tables together.

• The fields GIS draws on: cartography (map-making), statistics, computer science, remote sensing, and applied sciences such as planning, agriculture and hydrology.
• Its place in spatial information technology: GIS is one of five tools that work together:
• remote sensing collects images of the earth
• GPS / GNSS gives the exact position of a point
• GIS stores, combines and analyses the data
• digital cartography makes the maps
• DBMS manages the tables

The data a GIS handles

• Spatial data: data tied to a location and registered to a coordinate system, which is a fixed grid of latitude–longitude or map coordinates.

• NCERT Box 4.1 example: state-wise literacy rates are spatial, because each state can be found on a map.

• Non-spatial (attribute) data: descriptive data that have no location of their own.

• NCERT Box 4.1 example: a cycle shop's stock register (models, prices, quantities) is non-spatial.

• The three feature types (NCERT Fig. 4.1):

Feature	Nature	Examples
Point	One location, with no length or area	Wells, tube wells, bus stops, towns (at small scale)
Line	Has length but no width at map scale	Roads, rivers, railway lines, canals
Area / polygon	A closed boundary that covers space	Lakes, districts, forests, land-use parcels

• Scale decides the type: a city is a point on a map of India but an area on a district map.
• Three sources of spatial data: 1. Buy digital data, for example from Survey of India or the Bhuvan geoportal. 2. Digitise paper maps, which means converting them into computer form by tracing or scanning. 3. Do your own surveys with ground survey, GPS or remote sensing.
• The choice depends on the application, the budget and the data structure needed.

Components of GIS (NCERT Fig. 4.2)

Component	What it includes
Hardware	Computer, storage, digitiser or scanner, printer or plotter, GPS units
Software	Three modules: data entry and editing, analysis (query, overlay, buffer), and display and output (maps, tables, reports)
Data	Spatial and attribute data. Data are the backbone of GIS, because no analysis is possible without good data
People	Everyone from the engineers who build the system to the planners and decision-makers who use its results
Procedures	Set methods for collecting, checking, analysing and presenting data, so that results are reliable

What GIS can do that a paper map cannot

• The problem with a paper map: it shows one theme in one presentation, such as only soils or only roads. To change the theme, scale or colours, someone has to redraw it.
• The GIS solution: it keeps the data separate from the display, so the same data can be shown in many ways. Users can:
• Query features: click a district and see its population.
• Map the results of a search: for example, "show all districts with literacy below 60%".
• Run overlay analysis: stack layers such as soil, slope and rainfall to find land that suits a crop.
• Run buffering: draw a zone of fixed width around a feature, such as 500 m on both sides of a river or highway, and see what falls inside it.
• Join tables through a shared location code: link Census data and health data using a common district code.

Where it occurs

• India: Bhuvan. Bhuvan (Sanskrit for "Earth") is ISRO's geoportal, developed and run by NRSC (National Remote Sensing Centre), Hyderabad, at bhuvan.nrsc.gov.in. It lets users view remote sensing data and download satellite data free of cost. Government departments can also host their own applications on it [4].
• It runs about 150 web services that departments use for geospatial governance, which means governing with the help of maps and location data [5].

• Its modes include Standard, Thematic (natural-resource layers made by NRSC with State Remote Sensing Applications Centres), Data Hub & Analytics, and Disaster Services (near-real-time alerts) [5].

• India: Survey of India. It is a government source of digital spatial data, and it plays a key role in carrying out the National Geospatial Policy [7].

• India: policy framework.
• 2021: the Government announced liberalised guidelines for acquiring and producing geospatial data and services, including maps [6].
• National Geospatial Policy (NGP) 2022: notified on 28 December 2022, with a vision running to 2035 [3]. Prior approval, security clearance and licences were dropped and replaced by self-certification, where users declare for themselves that they follow the rules [2]. The policy is overseen by the Geospatial Data Promotion and Development Committee (GDPDC) [7].

• Operation Dronagiri was launched together with the GDI (Geospatial Data Integration platform) in 2024 as a milestone under the NGP [7].

• Data inputs over time: GIS draws on remote sensing data, from aerial photography to Landsat (1972) and India's IRS-1A (1988).

• Uses in planning: finding sites for facilities (overlay), marking flood or industrial risk zones (buffering), and work in urban planning, agriculture, hydrology and disaster management.

Don't confuse with

• Remote sensing: remote sensing collects images of the earth from aircraft or satellites. GIS stores, combines and analyses data, including those images.
• GPS / GNSS: GPS / GNSS only gives the exact position (latitude, longitude, height) of a point. GIS uses those positions as one input for its analysis.
• DBMS: a DBMS manages tables of descriptive data but does not know where things are. GIS links each table row to a place on the earth.
• Spatial information technology: this is the wider umbrella covering remote sensing, GPS, GIS, digital cartography and DBMS. GIS is one part of it.

Prelims Hooks

• GIS became possible from the mid-1970s. It draws on cartography, statistics, computer science and remote sensing.
• NCERT Box 4.1 trap: a cycle shop's stock register is non-spatial, but state-wise literacy is spatial.
• Feature matches: wells or towns → point; roads or rivers → line; lakes or districts → polygon (area).
• The five components of GIS are hardware, software, data, people and procedures. Data are called the backbone. The three software modules are data entry and editing, analysis, and display and output.
• Buffering draws a zone of fixed distance around a feature. Overlay stacks thematic layers. Paper maps cannot do either.
• Bhuvan is ISRO's geoportal, run by NRSC (Hyderabad), with free satellite data downloads [4]. The NGP was notified on 28 Dec 2022 and replaced security clearance with self-certification [2][3].

Mains Points

• GIS as a planning tool (GS-I/GS-III):
• It keeps data separate from the display, so one dataset can answer many questions.
• Overlay finds suitable sites, buffering marks flood or industrial risk zones, and district codes join Census and health data.

• This speeds up "what if" analysis in urban planning and disaster management.

• Policy has freed the data:

• The 2021 guidelines and NGP 2022 removed licensing and clearances and opened up publicly funded data [2][3][6].
• Free platforms like Bhuvan, with about 150 web services [5], lower costs for start-ups, states and researchers.

• Targets include a DEM (a digital map of ground height) at 25 cm accuracy for plains and 1–3 m for hills by 2030. By 2035 the targets are bathymetry (underwater depth maps), mapping of underground pipes and cables, and National Digital Twins (live digital copies) of major cities [3]. These support the Blue Economy, smart cities and flood modelling.

• Remaining challenges:

• The people and procedures components are still weak.
• There are not enough trained GIS staff, data standards differ between agencies, and digitised maps vary in quality.
• As a result, use of GIS lags behind what the data and policy now allow.

Related concepts

• Database management system
• Computer assisted cartography
• Spatial information technology
• Spatial data
• Attribute data
• Point, line and area features
• Advantages of GIS over manual maps
• Components of GIS

Read more

• Spatial information technology and GIS: concepts and components