Remote sensing and GIS are the two important aspects in geography. Nowadays these technologies are being used so extensively in numerous fields. Hence, at first it is important to provide a definition about remote sensing and GIS. 'Remote Sensing' is the technology of acquiring information about an object from a significant distance and without coming into contact with that object. The definition is quite clear from the two words that it consists of– 'remote' that means 'distance' (here the distant object) and 'sensing' which means 'to sense or feel' (here to acquire information). Thus the world literally depicts 'acquisition of information about a distant object'. In the other hand, GIS or Geographic Information System refers to a system which is used to capture, preserve, manipulate, analyse and present various geographic data in a scientific manner. Henceforth, it is also called 'GIScience' or 'Geographic Information Science'. Actually after getting information about an object through satellite remote sensing, then we analyse the acquired data through a computer based mapping or analysing tool called GIS.


What is Urban Sprawl ?

The term 'urban sprawl' denotes the gradual development of cities, or towns, or any other urban areas, in the peripheral region which are less accessible than the core area. In other words, urban sprawl refers to the unrestricted growth of any urban area in terms of built-up area, commercial development, and increase of road network over a large expanse of land, with a least urban planning. It is also known as 'sprawl' or 'suburban sprawl'.

It is important to note that the term 'urban sprawl' was first used in an article in a British daily national newspaper named 'The Times' in 1955 as a negative comment on the state of London's outskirts.

Application of Remote Sensing and GIS in Urban Sprawl Monitoring

In recent times, remote sensing and GIS technologies have been making significant contribution to the welfare of mankind, as well as the further development of the discipline geography. Nowadays, one of the most important application and implementation of remote sensing and GIS technology is the urban sprawl monitoring. It helps to determine the direction of expansion of urban areas, its pattern, and also for finding the suitable sites for further urban development.

The major areas or fields where remote sensing and GIS are used in the context of urban sprawl monitoring are as follows :

1. Mapping of Urban Sprawl

Urban sprawl is a gradual process which occurs due to the activities of human beings over a certain period of time. Urban planners use the remote sensing data and images, and GIS based mapping technology to prepare the map of sprawl of urban area.

2. Identifying the Expansion

The GIS based mapping tool helps to identify the the expansion or spreading of urban area, and also to determine its direction.


3. Urban Planning Process

There are also the use of GIS technology for urban planning process. Generally there are a shortage of urban basic amenities in the peripheral region or in the suburbs. Henceforth, the planners took up the task of quick decision making, management of assets efficiency, to allocate resources in the deficit regions, etc. through geographic information system.

4. Land Suitability Mapping

Remote sensing data and GIS can be used in order to identify suitable sites for sustainable urban growth, and to identify solution space for future development. In that case, some factors are taken into consideration, such as proper accessibility of land, vacant and more or less flat land, etc.

The imagery, showing the sprawl of urban area of the western portion of Las Vegas, are taken by Landsat-5  in 1984, 1999, and 2009 respectively from top to bottom | Image Courtesy : Britannica

5. Determining Transport and Drainage Network

By analysing satellite remote sensing data through geographic information system, one can determine the transport network, as well as surface or subsurface drainage network of the sprawling area. It also helps to demarcate the shortage areas of the said network systems in future for urban development.

6. Identifying Vegetation Cover

Shortage of green area or vegetation cover is a severe problem for all urbans. Rapid growth of built-up area gradually destroying the vegetation cover. Hence, satellite remote sensing images of the urban areas provides a clear picture of the amount of green spaces of the concerned areas, so that a sustainable environmental concern can be developed.

7. Data Analysis for Various Developmental Projects

GIS is useful for various urban developmental projects by analysing social, physical and economic data. Usually, GIS is applied to identify the best sites for the implementation of developmental projects.

8. Environmental Impact Assessment

Rapid urban growth affects the environment of the concerned area as well, especially if it's not in a sustainable way, that occurs an imbalance. GIS helps to make an effective environmental impact assessment for the urban areas.

At last but not the least, it can be said that, besides these aforementioned application of remote sensing and GIS, there are many othes field where these technologies may use quite extensively. These two technologies have emerged as a powerful tool, which helps to make a database of a long period of time for analysing sprawl of any urban area, its development, planning and many more.

For Further Study

Wikipedia | https://en.wikipedia.org/wiki/Urban_sprawl
Britannica | https://www.britannica.com/topic/urban-sprawl

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