First of all, we need to know what is remote sensing and GIS. When we acquire information about an object from a significant distance and without coming into contact with that object, then the process is called 'Remote Sensing'. Actually, 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 means 'acquisition of information about a distant object'. In the other hand, GIS or Geographic Information System denotes a system which is used to capture, preserve, manipulate, analyse and present various geographic data in a scientific manner. Hence, it is also called GIScience or Geographic Information Science. Actually after getting information about an object through remote sensing, then we analyse the acquired data through a computer based mapping or analysing tool called GIS.

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Application of Remote Sensing and Geographic Information System in Flood Management

Welfare of mankind has become possible by the advancement of remote sensing and GIS technology. The topic of interest is application of these technologies in the case of flood management. Nowadays, it has become possible to make a forecast, real time observation, quick damage mitigation of flood disaster through RS and GIS. GIS is a analysing or mapping tool that helps flood plain managers to demarcate and store information about flood prone areas in a community. It also assists to identify the different level of vulnerable areas by hazard mapping, as well as helps for mitigation of such problems.

In the following fields of flood management, GIS technology has succeeded to establish its application :

Applications_of_GIS_in_flood_management

1. Mapping of Flood Inundated Areas

It is important to make a map of the concerned flood inundated areas to develop a management plan or programme. Both the mapping of flooding and flood plain respectively during and after the flood are done through GIS. In this case, satellite remote sensing data and image of the concerned area are used for analysis through GIS, so that a proper planning and effective relief operation can be done immediately.

Mapping of flood inundated areas are done–

  • To demarcate the area extention of flood inundation.
  • To classify the affected area in terms of vulnerability.
  • To build up an effective relief operation
  • To assess the amount of damage
  • To make an evaluation of the impact of flood upon the human habitation as well as the environment.

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2. Zonation

Flood hazard mapping can be used for resident educating and administrative information purposes, and to regulate the flood plain development activities. For the zonation purpose– satellite data over a certain past time period, hydrological data, etc. are used to prepare the hazard mapping of the flood basins.

3. For Studying River Morphology

Remote sensing and GIS technology are used for studying river morphology which is directly or indirectly concern with flood hazard. Analysing the structure and form of river, such as river channel configuration, channel geometry etc. through GIS, the probability of flooding can be defined. In this case of morphological study, satellite remote sensing data are quite effective and feasible to identify the changing of the course of river in any specific time period, to identify and monitor the vulnerable reaches as well as the erosion prone areas along the river, etc.

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22 May, 2015 | Image Courtesy : NASA Earth Ovservatory

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17 Apr, 2020 | Image acquired by Operational Land Imagery (OLI) on Landsat 8, of flooded area along Red River in North Dakota | Image Courtesy : NASA Earth Ovservatory

The traditional methods of direct surveying for river morphological study is generally time consuming, whereas RS and GIS technology provides a helpful, effective and quite accurate information. Hence, these technologies are very helpful to easily implement different flood control structural measures, e.g.,  embankment construction, dredging in selected areas, channel improvement, etc.

17 Apr, 2020 | Map of concerned flooded area using 'Normalized Difference Water Index', a tool combining observations of infrared and visible light to make it easier to individualize between water and land | Image Courtesy : NASA Earth Ovservatory

At last but not the least, it can be said that remote sensing and GIS technology are very much useful to cope up with this type of disaster management. These two technologies have emerged as a powerful tool and is being used quite extensively for various flood management activities, and also to make a database of a long period of time for analysing historic flood to help inform the planning process and mitigation strategies.


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