Remote Sensing is the science of deriving information about the earth’s land water areas form images acquired at a distance. It relies upon measurement of electromagnetic energy reflected or emitted from the features of interest.
Remote Sensing can also be defined as the science or art of obtaining information about an object, area or phenomenon through the analysis of the data acquired by a device that is not in contact with the object, area or phenomenon under investigation.
Regardless of the orientation of the various definitions of Remote Sensing, the acquisition of images of earth surface features, using sensors, through the electromagnetic spectrum, the synoptic view advantage and Remote Se using’s ability to provide data for scientific technological and sustainable management and monitoring of the environment offer a convergence.
The Electro- magnetic spectrum (EMS) is the physical basis for Remote Sensing. It is an abstract idea and diagram of forms of electromagnetic energy for illuminating earth surface features.
The source of energy is divided according to wavelengths. The most widely used part of the spectrum is the visible portion (O.4u-O.7u) where the presence of atmospheric window reduces attenuation of energy to a considerable level.
The process of Remote Sensing involves making observation using sensors (camera, scanners, radiometers, radar, and lasers) mounted on platforms (ground, aircraft, satellites, balloons) which may be at considerable height from the earth surface.
Then, recording the observations on a suitable medium (photographic films and ma genetic tapes) or transmitting/down linking the data to a ground receiving station where the data are corrected for geometric and radiometric distortions.
Output products can be provided in computer compatible tapes (CC T) for users that made requests for the data.
Remote sensing serves as a tool for environmental resources (biotic, abiotic and cultural) assessment and monitoring. Remote sensing has some fundamental advantages that make it a veritable tool in environmental monitoring and management and impact studies.
A capability for recording more permanently detected patterns.
Play-back facility at different speeds.
Opportunity for automatic (objective) analysis of observations to minimize personal peculiarities of observers.
Means of enhancing images to reveal or highlight selected phenomena.
The synoptic view advantage offered by raised platforms is the ability to record data on otherwise inaccessible areas.
Ability to produce accurate data on large areas at desired time intervals and at relatively lower cost compared to the cost that would be incurred through ground survey methods.
Ability to record images in multispectral fashion at different stages, at different scale and spatial resolutions.
Remote sensing data also possess high geometric precision detail, consistency, cost effectiveness and adaptation to highly difficult terrains.
All these combine to make Remote Sensing a veritable tool for obtaining baseline information for establishing baseline conditions of an area at the pre-project analysis stage, as well as monitoring changes in the environmental conditions of such area after the project has been de- commissioned.
Geographical Information System (GIS)
The application of Geographic Information Systems (GIS) in the Environmental Impact Assessment (EIA) process has gained substantial momentum over the past few years.
Even so, the misconception exists that GIS involves mapping only, and many companies are still unaware of the robust solutions and cost savings this tool has to offer, when correctly implemented.
The SRK Natal team has been at the forefront of developing the applied specialist skills required to integrate the use of GIS as spatial information, decision-making tool in EIAs internationally.
The focus here is on applied integration, as it requires the person undertaking the analysis to understand the project, the potential environmental issues associated with it, and how the GIS can assist in obtaining the desired results.
Accessibility to good quality, up-to-date spatial information has improved significantly and data is becoming more accurate. Inferior quality spatial data still exists, however, and it is essential that the GIS user is familiar with the quality of the spatial data prior to use.
In addition to identifying and analyzing potential impacts, a GIS is also a powerful spatial planning tool. For example, a GIS is often used to identify sites suitable for establishing cemeteries and waste disposal facilities.
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Overlaying several spatial datasets (soil type, vegetation, ground and surface water, geology etc.), with specific assessment criteria for each, can produce a map indicating suitable and unsuitable areas.
SRK is currently undertaking a similar exercise identifying potential corridors suitable for establishing a 250-kilometer section of powerline on the Makhathini Flats in northern KwaZulu-Natal.
The powerline will traverse areas of pristine and highly protected sand forest species. In this instance a GIS is being used to calculate the shortest possible route, taking into consideration the environmental issues in the area.
This method has already led to time savings on the project and has achieved a significant cost saving for the client.
In summary, the process of Remote Sensing involves making observation using sensors (camera, scanners, radiometers, radar, and lasers) mounted on platforms (ground, aircraft, satellites, balloons) which may be at considerable height from the earth surface.
Then, recording the observations on a suitable medium (photographic films and ma genetic tapes) or transmitting/down linking the data to a ground receiving station where the data are corrected for geometric and radiometric distortions.
Remote sensing serves as a tool for environmental resources (biotic, abiotic and cultural) assessment and monitoring. Remote sensing has some fundamental advantages that make it a veritable tool in environmental monitoring and management and impact studies.
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