Remote sensing- GIS and its application
Remote Sensing
Remote sensing is the acquisition of information about an object or phenomenon without making physical contact with the object and thus in contrast to on-site observation.
In current usage, the term “remote sensing” generally refers to the use of satellite- or aircraft-based sensor technologies to detect and classify objects on Earth, including on the surface and in the atmosphere and oceans, based on propagated signals.
Remote sensing is used in numerous fields, including geography, land surveying and most Earth Science disciplines for example, hydrology, ecology, oceanography, glaciology, geology. It also has military, intelligence, commercial, economic, planning, and humanitarian applications.
GIS
Geographic Information System (GIS) is a computer based application of technology involving spatial and attributes information to act as a decision support tool.
It keeps information in different layers and generates various combinations pertaining to the requirement of the decision-making. In the recent times, GIS has emerged as an effective tool in management of disasters since, geo-spatial data and socio-economic information need to be amalgamated for the better decision making in handling a disaster or to plan for tackling a disaster in a better way.
Applications:
Disaster Management
The different line departments and agencies who are stakeholders in the disaster management process could utilize GIS. Some basic hardware like computer system, printer, network systems, along with GIS software is required to set up the GIS in any organisation.
Objectives:
The prime objectives of developing the GIS database are to help disaster managers at State, District and Block level for:
i) Pre-disaster planning and preparedness
ii) Prediction and early warning
iii) Damage assessment and relief management
GIS combines layers of information on various themes to enable the managers to take the most appropriate decisions under the given circumstances. For disaster management, a GIS database could be a useful managerial tool for various reasons, some of which are as under:
• Disaster Managers could generate maps both at micro and macro level indicating vulnerability to different extents under different threat perceptions.
• Locations likely to remain unaffected or remain comparatively safe could be identified.
• Alternate routes to shelters, camps, and important locations in the event of disruption of normal surface communication could be worked out.
• Smooth rescue and evacuation operations could be properly planned.
• Rehabilitation and post-disaster reconstruction works could be properly organized.
• Locations suitable for construction of shelters, godowns, housing colonies, etc. can be scientifically identified.
• Areas where no construction should be taken up or existing habitations require relocation could be identified.
Hydrology
Remote sensing of hydrologic processes can provide information on locations where in situ sensors may be unavailable or sparse. It also enables observations over large spatial extents. Many of the variables constituting the terrestrial water balance, for example surface water storage, soil moisture, precipitation, evapotranspiration, and snow and ice, are measurable using remote sensing at various spatial-temporal resolutions and accuracies. Sources of remote sensing include land-based sensors, airborne sensors and satellite sensors, which can capture microwave, thermal and near-infrared data or use LIDAR.
Weather forecasting and Ecology
Many ecological research projects would benefit from the creation of a GIS to explore spatial relationships within and between the data. In particular, while some projects can be done without using a GIS, many will be greatly enhanced by using it (click here for some examples of research projects which have used GIS).
The very act of creating a GIS will make you think about the spatial relationships within your data, and will help you formulate hypotheses to test or suggest new ones to explore. In addition, thinking about your data in a spatial manner will help you identify potential spatial issues and/or biases with your data.
GIS can also be used to make measurements and carry out calculations which would otherwise be very difficult. For example, a GIS can be used to work out how much of your study area consists of a specific habitat type, or how much of it is over 1,000m high, or has a gradient greater than 5º, and so on. Similarly, a GIS can be used to calculate the size of the home range of an individual or the total area occupied by a specific species or how long your survey tracks are, or how much survey effort was put into different parts of your study area.
GIS can also be used to link data together in the way that is needed for statistical analysis. For example, many statistical packages require all your data to be in a single table, with one line per sample and then information about that sample and the location where it came from in different columns or fields. A GIS provides you with a way to easily create such tables and populate it with information, such as the altitude at each location, the gradient of slope and the direction it faces, from other data sets. This makes preparing your data for statistical analysis much simpler.