Remote Sensinging Theory In Lake Nasser
The aim of this chapter is to give a detailed review of remote sensing theory and its application in lakes/reservoirs, rivers, estuaries and coastal zones, especially in water quality. It will also give a review about the researches pertain the use of remote sensing techniques in Lake Nasser.
2.2. Remote sensing theory
Remote sensing, also called earth observation, is a way to get information about objects by collecting and analyzing data without being in direct contact with the object or area. In general terms, remote sensing is a tool to observe and study the Earth, its land surface, the oceans, the atmosphere and its dynamics from space. It offers a means of obtaining large amounts of data, but its value is in the information that is obtained from the acquired data …show more content…
Figure (2 2) The electromagnetic spectrum, (Tantirimudalige, 2002)
2.2.3. Types of remote sensing
Remote sensing can be classified according to either energy source or sensor type into passive or active systems. Active systems have their own source of energy such as microwaves (radar), whereas the passive systems depend upon external source of illumination, such as sun or self-emission of the observed object.
Also remote can be classified according to the wavelengths into three categories as follows:
1- Visible and near infrared Remote Sensing, this type can be classified as a passive system where it depends on the reflected energy from the sun. It helps in understanding of land surface conditions such as vegetation, rivers, lakes, and urban areas distribution. Also it can be used in field of water quality monitoring.
2- Thermal Infrared Remote Sensing, this type classified as a passive system where it depends on collecting the thermal infrared rays radiated from land surface heated by sunlight. It can be used in identifying the high temperature area such as volcanic activities and fires