39 Applications of GIS and GPS

Prachi Mishra Sahoo

1.Learning outcomes
2. Introduction
3. Geographical Information System (GIS)
3.1. Components of GIS
3.2. Formats of GIS data
3.2.1. Vector dormat
3.2.2. Raster dormat
3.3. Data Input in GIS
3.4. Basic GIS functionality
3.5. Questions GIS can answers
4. Applications of GIS
4.1. GIS applications in atmospheric sciences
5. Global Positioning System (GPS)
5.1. Segments of GPS
5.1.1. Space segment
5.1.2. Control segment (CS)
5.1.3. User segment
5.2. Functioning of GPS
5.3. Indian Global Positioning System – GAGAN
6. Applications of GPS
6.1. Timing
6.2. Roads and highways
6.3. Space
6.4. Aviation
6.5. Agriculture
6.6. Surveying and mapping
6.7. GPS and precision agriculture
6.8. Soil sampling using GPS
7. Summary

1. Learning outcomes

After studying this module, you shall be able to:

• Know the concept and definition of GIS and GPS
• Know the major components of GIS and GPS systems and their functions
• Appreciate the power of GIS and GPS tools in scientific studies and making life easier
• Know various applications of GIS and GPS
• Know indigenous and globally developed GIS and GPS

2. Introduction

Geographical Information System (GIS) is a modern and efficient tool for handling spatial data. It is an integrated computer based system of geography and information tied together. The applications of GIS are immense pertaining to almost all disciplines. Global Positioning System (GPS) further enhances the capability of GIS by providing real time positional data along with several applications. In this module working of GIS and GPS is briefly explained along with their areas of applications.

3. Geographical Information System (GIS)

GIS is a system of hardware, software, and procedures designed to support the capture, management, manipulation, analysis, modeling and display of spatially-referenced data for solving complex planning and management problems. It is an integrated system that is designed to work with spatial and attribute data. In other words, a GIS is both a system with specific capabilities for spatially-referenced data, as well as a set of operations for working with non-spatial data.

3.1.  Components of GIS

GIS integrates five key components: hardware, software, data, people, and methods.

Hardware: Hardware is the computer system on which a GIS operates and the GIS software runs. The computer forms the backbone of the GIS hardware; besides this it needs input and output devices. Scanner and or digitizer board are the most common input devices whereas printers and plotters are output devices for a GIS hardware setup.

Software: GIS software provides the functions and tools needed to store, analyze, and display geographic information. Key software components are

• Data input and verification
• Data storage and database management
• Data transformation
• Data output and presentation
  • Interaction with the user

Data: The most important component of GIS is the data. GIS has two types of data-

• Spatial data – Spatial data refers to all types of data objects or elements that are present in a geographical space. It enables the global finding and location of individuals or devices anywhere in the world. Spatial data is also known as geospatial or geographic data.
• Attribute data – Attribute data is information appended in tabular format with respect to the spatial features. Attribute data provides characteristics about spatial data.

Method: Above all a successful GIS operates according to a well-designed plan and business rules, which are the models and operating practices unique to each organization. There are various techniques used for map creation and further usage for any project.

3.2. Formats of GIS Data

In GIS, the spatial data can be represented in two formats: Vector format and Raster format which are described below:

3.2.1.Vector Format

In vector format, any real feature on earth is represented either as Point, Line or Polygon. In vector models, objects are created by connecting points with straight line (or arcs) and area is defined by sets of lines. Information about points, lines and polygons is encoded and stored as a collection of x, y coordinate. Location of a point feature such as tubewell can be described by a single x, y coordinate. Linear feature such as river can be stored as a collection of point coordinates. Polygon feature, such as river catchment can be stored as a closed loop of coordinates.

3.2.2.   Raster Format

Raster data represents all information in square pixel (PIXEL = Picture Element) form which is the smallest unit of whole raster representation. In raster format, study area is divided into a regular grid of cells in which each cell contains single value. Continuous data type, such as elevation, vegetation etc. are represented using raster model.

3.3. Data Input in GIS

After receiving existing spatial data, it needs to be converted into digital format which is compatible with the GIS software. This data could be obtained by primary data sources, such as satellite or GPS (Global Positioning System), or secondary data sources such as paper maps. The process of converting paper maps to digital data is called digitizing, and it can be done using digitizer or scanner. Another method is on-screen digitization which is manual digitizing on the computer monitor using a data source such as a raster image or toposheet as the background.

3.4.Basic GIS functionality

GIS software combines computer mapping functionality that handles and displays spatial data, with database management system functionality to handle attribute data. The basic functionality of GIS is as follows:

• Querying both spatial and attribute data
• Manipulating the spatial component of the data
• Buffering where all locations lying within a set distance of a feature or set of features are identified
• Overlaying which involves data integration using one or multiple layers using a mathematical overlay operation
• Areal interpolation

3.5. Questions GIS can answers

A spatial database created in GIS allows us to ask questions such as ‘what is at this location?’, ‘where are these features found?’ and ‘what is near this feature?’ It also allows us to integrate data from a variety of disparate sources. However, GIS can answer more complicated questions pertaining to like location, condition, trends, patterns, modeling etc. Some of the common questions which GIS can answer are:

Location: What is at………….?

Condition: Where is it………….?

Trends: What has changed since…………..?

Patterns: What spatial patterns exists…………..?

Modeling: What if……………..?

Spatial Questions: Which centres lie within 10 km of each other?

Non spatial Questions

4.0. Applications of GIS

GIS has emerged as very powerful technology to integrate spatial and attribute data and methods in ways that support traditional forms of geographical analysis, such as map overlay analysis as well as new types of analysis and modeling that are beyond the capability of manual methods. With GIS it is possible to map, model, query, and analyze large quantities of data all held together within a single database. The development of GIS has relied on innovations made in many different disciplines like Geography and Cartography. GIS is now used extensively in government, business, and research for a wide range of applications including environmental resource analysis, land use planning, locational analysis, tax appraisal, utility and infrastructure planning, real estate analysis, marketing and demographic analysis, habitat studies and archaeological analysis. Not only this, GIS can be applied as a tool in almost all disciplines of science and technology like Photogrammetry, Remote Sensing, Surveying, Geodesy, Civil Engineering, Statistics, Computer Science, Operations Research, Artificial Intelligence, Demography and many other branches of the social sciences, natural sciences and engineering. Indeed, some of the most interesting applications of GIS technology discussed below draw upon this interdisciplinary character and heritage.

One of the first major areas of application was in natural resources management, including management of

• wildlife habitat
• wild and scenic rivers
• recreation resources
• floodplains
• wetlands
• agricultural lands
• aquifers
• forests

One of the largest areas of application has been in facilities management. Uses for GIS in this area includes

• locating underground pipes and cables
• balancing loads in electrical networks
• planning facility maintenance
• tracking energy use

Local, state, and federal governments have found GIS particularly useful in land management. GIS has been commonly applied in areas like

• zoning and subdivision planning
• land acquisition
• environmental impact policy
• water quality management
• maintenance of ownership

More recent and innovative uses of GIS have used information based on street-networks. GIS has been found to be particularly useful in

• address matching
• location analysis or site selection
• development of evacuation plans

The range of applications for GIS is growing as systems become more efficient, more common, and less expensive. Some of the newest applications have taken GIS to unexpected areas. The USGS (United States Geological Survey) and the city of Boulder, Colorado in USA have come up with some innovative uses for GIS:

• Global Change and Climate History Project
• Emergency Response Planning
• Site Selection of Water Wells
• Wildfire Hazard Identification and Mitigation System

4.1. GIS applications in atmospheric sciences

GIS and other geospatial technologies have become increasingly valuable to the atmospheric sciences, such as weather, climate, hydrometeorology and for societal impact studies.

• Assessment of wind/storm speed using interpolation

Inverse Distance Weighted (IDW) interpolation is commonly used in GIS to create raster overlays from point data. Once the data are on a regular grid, contour lines can be threaded through the interpolated values and the map can be drawn as either a vector contour map or as a raster-shaded map.

• Average annual lightning strike density

In figure 5, lighting strike density in an area was mapped using course resolution raster data.

•       Wind speed mapping using TIN Method and linear models

TIN (Triangular Irregular Network) is another tool in GIS and it is a vector data structure. It creates a surface formed by triangles of nearest points. In figure 7 wind speed was mapped and shown as continuous raster surface model. Models can also be developed using linear relationships as shown in figure 8.

• Tracking of tornado outbreaks
• Tracking of tsumani arrival
• Speeding power restoration after a storm

5. Global Positioning System (GPS)

The  Global  Positioning  System  (GPS)  is  a  space-based  navigation  system  that  provides  reliable positioning, navigation, and timing services. Most widely used GPS was developed by the US military, which is named as NAVSTAR, in 1950’s. Initially it’s services were solely available for the use of army, later on it has been made accessible to civilian users too and nowadays it provides continuous worldwide service, free to all. Some other countries have also put in place similar space-based navigation system like that of NAVSTAR-GPS. Examples include GLONASS (Russia), Galileo (Europe) and Beidou (China).

5.1. Segments of GPS

There are three major segments of GPS. These are (i) Space segment, (ii) User segment and (iii) Control segment.

The Space Segment consists of

the constellation of spacecraft/satellites and the signals broadcast by them allow users to determine position, velocity and time. The basic functions of the satellites are to:

• Receive and store data transmitted by the control segment stations
• Maintain accurate time by means of several onboard atomic clocks
• Transmit information and signals to users on two L-band frequencies

The Space Segment is an earth-orbiting constellation of 24 active and five spare GPS satellites circling the earth in six orbital planes. Each satellite is oriented at an angle of 55 degrees to the equator. The nominal circular orbit is at 20,200 kilometers (10,900 nautical miles) altitude. Each satellite completes one earth orbit every twelve hours (two orbits every 24 hours). That’s an orbital speed of about 4 km per second.

Each GPS satellite (Figure 10) transmits a unique navigational signal centered on two L-band frequencies of the electromagnetic spectrum, permitting the ionospheric propagation effect on the signals to be eliminated. At these frequencies the signals are highly directional and so are easily reflected or blocked by solid objects. Clouds are easily penetrated, but the signals may be blocked by foliage (the extent of blockage is dependent on the type and density of the leaves and branches).

5.1.2.   Control segment (CS)

The CS has responsibility for maintaining the satellites and their proper functioning. This includes maintaining the satellites in their proper orbital positions (called station keeping) and monitoring satellite health and status. The CS (Figure 11) also monitors the satellite solar arrays, battery power levels. There are five ground facility stations of NAVSTAR-GPS, viz., Hawaii, Colorado Springs, Ascension Island, Diego Garcia and Kwajalein. All are owned and operated by the U.S. Department of Defence and perform the following functions:

• All the five aforesaid stations are Monitoring Stations, equipped with GPS receivers to track the satellites. The resultant tracking data is sent to the Master Control Station.
• Colorado Springs is the Master Control Station (MCS), where the tracking data are processed in order to compute the satellite ephemerides and satellite clock corrections. It is also the station that initiates all operations of the space segment, such as spacecraft manoeuvring, signal encryption, satellite clock-keeping etc.
• Three of the stations, viz., Ascension Island, Diego Garcia and Kwajalein are Upload Stations allowing for the uplink of data to the satellites. The data includes the orbit and clock correction information transmitted within the navigation message, as well as command telemetry from the MCS.

Overall operation of the Control and Space Segments is the responsibility of the U.S. Air Force Space Command, Second Space Wing, Satellite Control Squadron at the Falcon Air Force Base, Colorado.The GPS satellites travel at high velocity (4 km s-1), but within a more or less regular orbit pattern. After a satellite has separated from its launch rocket and it begins orbiting the earth, its orbit is defined by its initial position and velocity, and the various force fields acting on the satellite.

5.1.3. User Segment

5.2. Functioning of GPS

The GPS system consists of three pieces. There are the satellites that transmit the position information, there are the ground stations that are used to control the satellites and update the information, and finally there is the receiver that one purchases. It is the receiver that collects data from the satellites and computes its location anywhere in the world based on information it gets from the satellites. There is a popular misconception that a GPS receiver somehow sends information to the satellites but this is not true, it only receives data.

5.3.Indian Global Positioning System – GAGAN

In August 2001 the Airports Authority of India and the Indian Space Research Organization (ISRO) reached an agreement for the establishment of the GAGAN (GPS Aided Geo Augmented Navigation) system (Figure 13).The development plan consists of three different phases-

• Technology Demonstration System (TDS) Initial Experimental Phase (IEP)
• Final Operational phase (FOP)
• GAGAN Stability tests were successfully completed in June 2013.

The GAGAN is designed to provide the additional accuracy, availability, and integrity necessary to enable users to rely on GPS for all phases of flight, from en route through approach for all qualified airports within the GAGAN service volume. GAGAN will also provide the capability for increased accuracy in position reporting, allowing for more uniform and high-quality Air Traffic Management (ATM). In addition, GAGAN will provide benefits beyond aviation to all modes of transportation, including maritime, highways, railroads and public services such as defense services, security agencies, telecom industry and personal users of position location applications (Source: ISRO Satellite Centre, ISAC).

6. Applications of GPS

6.1.Timing

In addition to longitude, latitude and altitude, the Global Positioning System (GPS) provides a critical fourth dimension – time. Each GPS satellite contains multiple atomic clocks that contribute very precise time data to the GPS signals. GPS receivers decode these signals, effectively synchronizing each receiver to the atomic clocks. This enables users to determine the time to within 100 billionths of a second, without the cost of owning and operating atomic clocks. Precise time is crucial to a variety of economic activities around the world. Communication systems, electrical power grids and financial networks, all rely on precision timing for synchronization and operational efficiency. The free availability of GPS time has enabled cost savings for companies that depend on precise time and has led to significant advances in capability.

6.2.Roads and highways

It is estimated that delays from congestion on highways, streets, and transit systems throughout the world result in productivity losses in hundreds of billions of dollars annually. Other negative effects of congestion include property damage, personal injuries, increased air pollution and inefficient fuel consumption. The availability and accuracy of the Global Positioning System (GPS) offers increased efficiencies and safety for vehicles using highways, streets and mass transit systems. Many of the problems associated with the routing and dispatch of commercial vehicles is significantly reduced or eliminated with the help of GPS. Many nations

use GPS to help survey their road and highway networks, by identifying the location of features on, near, or adjacent to the road networks. These include service stations, maintenance and emergency services and supplies, entry and exit ramps, damage to the road system etc. The information serves as an input to the GIS data gathering process. This database of knowledge helps transportation agencies to reduce maintenance and service costs and enhances the safety of drivers using the roads.

6.3.Space

The Global Positioning System (GPS) is revolutionizing and revitalizing the way nations operate in space, from guidance systems for crewed vehicles to the management, tracking and control of communication satellite constellations, to monitoring the earth from space. Benefits of using GPS include:

• Navigation solutions: providing high precision orbit determination, and minimum ground control crews, with existing space-qualified GPS units
• Attitude solutions: replacing high cost on-board attitude sensors with low-cost multiple GPS antennae and specialized algorithms.
• Timing solutions: replacing expensive spacecraft atomic clocks with low-cost, precise time GPS receivers.

6.4. Aviation

Aviators throughout the world use the Global Positioning System (GPS) to increase the safety and efficiency of flight. With its accurate, continuous, and global capabilities, GPS offers seamless satellite navigation services that satisfy many of the requirements for aviation users. Space-based position and navigation enables three-dimensional position determination for all phases of flight from departure, en route, arrival, to airport surface navigation. New and more efficient air routes made possible by GPS are continuing to expand. Vast savings in time and money are being realized. In many cases, aircraft flying over data-sparse areas such as oceans have been able to safely reduce their separation between one another, allowing more aircraft to fly more favourable and efficient routes, saving time, fuel, and increasing cargo revenue.

6.5. Agriculture

The development and implementation of precision agriculture or site-specific farming has been made possible by combining the Global Positioning System (GPS) and Geographic Information System (GIS). These technologies enable the coupling of real-time data collection with accurate position information, leading to the efficient manipulation and analysis of large amounts of geospatial data. GPS-based applications in precision farming are being used for farm planning, field mapping, soil sampling, tractor guidance, crop scouting, variable rate applications of inputs like pesticide or fertilizer applications and yield mapping. GPS allows farmers to work during low visibility field conditions such as rain, dust, fog, and darkness.

6.6. Surveying and Mapping

Using the near pinpoint accuracy provided by the Global Positioning System (GPS) with ground augmentations, highly accurate surveying and mapping results can be rapidly obtained, thereby significantly reducing the amount of equipment and labour hours that are normally required of other conventional surveying and mapping techniques. Today it is possible for a single surveyor to accomplish in one day what used to take weeks with an entire team. GPS is unaffected by rain, wind, or reduced sunlight, and is rapidly being adopted by professional surveyors and mapping personnel throughout the world.

6.7. GPS and Precision Agriculture

The main objective of precision agriculture is to get more and more output by providing optimum input. Precision Agriculture is doing the right thing, at the right place, at the right time. Knowing the right thing to do may involve all kinds of high tech equipments and fancy statistics or other analysis. In this context, GPS becomes part of precision agriculture. For analysis and processing of remote sensed images requires ground truth information, collected in the field, at a variety of sites and often at various times throughout the crop production season. Conventionally this data has been manually recorded on field sheets, air photos or paper maps and considerable time and effort is required to convert it to digital format for use in remote sensing or GIS. For image analysis the ground data must be digitized in order to create a mask for training the software to recognize different conditions and classify the remote sensing imagery. Now we have an interactive, portable system to record field data directly into a digital database consisting of yield, soil, road, water and contour maps overlain on air photos or remote sensing imagery. A GPS receiver is linked to a note book computer displaying appropriate, pre loaded information layers, and a software package then combines incoming GPS signals with the displayed data to allow the user to see where they are with respect to the map components.

In agricultural production soil is the media on which seeds are shown or a plant is planted. Whether growing forage, feed, food or fibre, plant growth depends on soil conditions and soil quality. The following section describes how GPS are used for soil sampling and mapping purposes.

6.8. Soil sampling using GPS

Soil Sampling is like the foundation of a house. No matter how much effort we put into building the house, the house is only as good as the foundation. The same principle applies to precision agriculture. To effectively manage soil-plant interrelationships, thematic information on soil across the length and breadth of the field is very important.

Grid sampling is used for precision agriculture because it is simple and does not require soil science experience. Once the soil data has been collected, the data can be displayed and analyzed.

There are two basic types of grid sampling (Figure 17) used to collect soil data for precision agriculture.

These are:

• Area sampling (grid cell)
• Point sampling with interpolation (grid point)

Determining and mapping the variation in soil characteristics across a field requires an accurate knowledge of the position that the samples were taken. Whichever grid sampling method is used, the coordinate location of the soil sample should be accurate for developing a soils data layer and for navigating back to those locations for re-sampling. This requires the use of a GPS receiver and a source of differential corrections so the producer can acquire an accurate (1- 2 meter) horizontal position that represents the soil sample location. Having acquired the coordinates, the position can be entered into a database while in the field. After the soil sample location has been accurately acquired and entered into a database, all the physical soils data (texture, pH, nutrients etc.) can be tagged to the coordinate location.

7. Summary

We have learnt the following in this lesson:

• GIS is system for capturing, storing, integrating, manipulating, analyzing and displaying spatially data. GPS is basically a system to determine precise location of an object and its main purpose is to aid in navigation.
• Hardware, Software, Data, People and Method are the major components of GIS. Vector and Raster are the two important data formats in GIS.
• Querying, Overlaying and Buffering are the key functions of GIS. There are three major segments of GPS- Space segment (satellites), Control segment (ground stations) and User segment (the receiver)
• Some functional GPS service systems in the world include NAVSTAR (USA), GLONASS (Russia), Galileo (Europe) etc. India has also developed its own Global Positioning System (GAGAN).
• In combination with various scientific and applied disciplines (e.g., Computer Science, Statistics, Meteorology, Soil Science, Geography, Cartography, Photogrammetry & Remote Sensing, Civil Engineering) the applications of GIS and GPS, nowadays, caters to the need of a very wide range of sectors. Examples include roadways or waterways transportation, aviation, artificial intelligence, real time weather monitoring & forecasting, climatic mapping, rescue and search operations during exigencies, disaster management, land cover change detection & land use planning, agriculture (particularly the precision agriculture), natural resources exploration (e.g., oil & mineral mapping), corporate governance and implementation/monitoring of societal programmes.