Water and vegetation

Water
Water covers about 70% of the earth’s surface and as a basic resource for the survival of the human species is approaching crisis levels. In recent decades, numerous initiatives have been undertaken to protect and regulate this resource by keeping a check on certain parameters that are indicative of water quality, such as colour, turbidity, chlorophyll, temperature, algal distribution and the highly dangerous pollution caused by hydrocarbons and/or chemical products.

Water color
Suspended material, coloured pigments, as well as the presence of dissolved carbon and humus fraction influence the chromatic values in visible band (blue, green and red). Analysis of the three colour components (saturation, tone and intensity) is sufficient to determine the trophic state of any given water mass, at least on a qualitative level in the three oligotrophic, mesotrophic and eutrophic classes.

Maps of Torbidity
Turbidity is one of the parameters that enables us to evaluate the quality of water. For example, low levels of turbidity is a major factor in identifying areas of high quality tourism. In order to examine water quality, the level of turbidity can be gauged directly from satellite or aerial images in terms of a Transparency Index .

Using remote sensing, it is also possible to assess the Beam Attenuation Coefficient (BAC) of water, a parameter that is correlated with suspended solids in well-defined depth bands.

Determination of Chlorophyll content – A
The chlorophyll content of water is an index of the level of development and growth of algal vegetation. The existence of chlorophyll in water is a major factor in determining the degree of radiancy reflected off the water surface, and it therefore follows that the chlorophyll content of water can be assessed from an analysis of satellite images .

Temperature Maps The use of the distant infrared spectral band (10. 4-12.5 mm) makes it possible to create maps of surface temperature and to follow changes in such temperatures over time. Using a suitable geometric scale for the problem under examination, it is also possible to accurately identify points of discharge in the water mass

Algal Distribution
Using aerial multi-spectral sensors, it is possible to map the position of algal vegetation in shallow water and to obtain, by means of multi-temporal checks, a monitoring of major biological parameters, (for example, the Posidonia oceanica). Furthermore, it is possible to assess by means of multi-temporal analyses, the existence and development of mucilage on seawater surface .

Cortesy of CNR Lara

Hydrocarbons and Chemical product in seawater
Oil slicks in the sea may appear following an accident, involving ships or oil rigs, or as a result of the illegal spillage of oleous waste. Removing and controlling such oil slicks is of primary importance in the attempt to limit the devastating effects of the same on the marine environment.

The precise location, density and extent of any oil spillage at sea may be determined through the processing of SPOT panchromatic images or by ERS or RADARSAT radar .

Vegetation Territorial Informational Systems technology offers us countless possibilities for keeping a control on our plant heritage, these range from such topics as identifying the form of plant cover, deforestation, the state of health of the vegetation, to the prevention and control of forest fires. This is, by no means a complete list as the possible applications are innumerable .

State of plant health

Fires are one of the most difficult environmental problems to control, with sometimes drastic consequences both for man and the environment in general.

A study of images obtained by remote sensing techniques can enable us to evaluate the degree of stress on vegetation and so plan the best form of action. In this way, the use of chemical products can be rationalized with a consequent saving in both time and money.

This type of analysis also helps to conserve the environment through a reduction in the quantity of chemical substances used which penetrate the soil and the water system .

Prevention and control of forest fires
Through an analysis of the territory and the state of plant cover, it is possible to perfect software for models of fire development with which it is possible to have instruments capable of indicating the site where a fire could start, in which direction it could spread, and with what intensity. An appropriate territorial informational system would enable a rapid evaluation of the level of danger and the consequent planning of prevention, containment and rescue .