18-07-2012, 12:44 PM
LAND COVER MAPPING FOR VEMPALLI MANDAL BY USING REMOTE SENSING AND GIS
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INTRODUCTION
A modern nation, as a modern business, must have adequate information on many complex interrelated aspects of its activities in order to make decisions. Land use is only one such aspect, but knowledge about land use and land cover has become increasingly important as the Nation plans to overcome the problems of haphazard, uncontrolled development, deteriorating environmental quality, loss of prime agricultural lands, destruction of important wetlands, and loss of fish and wildlife habitat. Land use data are needed in the analysis of environmental processes and problems that must be understood if living conditions and standards are to be improved or maintained at current levels.
GENERAL:
The use of remote sensing techniques has become increasingly important in describing a variety of satellite-derived data sets and their application to understand changes in the landscape (Kouchoukos et al., 1997). Remote sensing has long been recommended for its potential to detect, map and monitor degradation problems (Hellden and Stern, 1980; Sabins, 1987; Frederiksen, 1993; Mohammed, 1993; Raina et al., 1993; Tripathy et al., 1996; Sujatha et al., 2000) including their spread and effects with time (Sommer et al., 1998). Use of remotely sensed imagery evolved on the basis that traditional survey becomes expensive and time-consuming. It is especially useful in areas that are not accessible.
INTRODUCTION OF REMOTE SENSING
Remote sensing may be broadly defined as the collection of information about an object without being in physical contact with the object. The term remote sensing is restricted to methods that employ electromagnetic energy as the means of detecting and measuring target characteristics. Electromagnetic energy refers to all energy that moves with the velocity of light in a harmonic wave pattern. Sensors (Cameras, Scanners etc) installed in satellites or aircraft react to the electromagnetic radiation to produce data/images, which provide a synoptic overview giving a comprehensive picture of the terrain features. Electromagnetic energy is commonly considered to span the spectrum of wavelength from 10 µm, the cosmic rays, up to 10 µm, the broadcast wavelength.
DEFINITION OF REMOTE SENSING
Remote sensing technique defined as – The science and art of acquiring information about objects from measurements made at a distance without any physical contact with the objects.
APPLICATIONS OF REMOTE SENSING
Remote Sensing data both in image form and in digital format is utilized for deriving information about resources either adopting visual interpretation techniques or computer aided analysis. Both the types of methods require certain amount of ground support information, which is normally collected by the interpreter to develop key or to feed training sets to computers prior to analysis and interpretation and this is normally referred to as “GROUND TRUTH”. Using ground truth the Remote Sensing data are analysed, interpreted and maps related to resources are generated.