Publication Date:
2008
Description:
〈b〉Use of remote sensing and GIS in mapping the environmental sensitivity areas for desertification of Egyptian territory〈/b〉〈br〉
A. Gad and I. Lotfy〈br〉
eEarth Discuss., 3, 41-85, doi:10.5194/eed-3-41-2008, 2008〈br〉
〈b〉Revised manuscript has not been submitted〈/b〉 (discussion: closed, 3 comments)〈br〉
Desertification is defined in the first art of the convention to combat
desertification as 〈i〉"land degradation in arid, semiarid and dry
sub-humid areas resulting from climatic variations and human activities".〈/i〉 Its consequence include a set of important processes
which are active in arid and semi arid environment, where water is the main
limiting factor of land use performance in such ecosystem . Desertification
indicators or the groups of associated indicators should be focused on a
single process. They should be based on available reliable information
sources, including remotely sensed images, topographic data (maps or DEM'S),
climate, soils and geological data. The current work aims to map the
Environmental Sensitivity Areas (ESA's) to desertification in whole
territory of Egypt at a scale of 1:1 000 000.
〈br〉〈br〉
ETM satellite images, geologic and soil maps were used as main sources for
calculating the index of Environmental Sensitivity Areas (ESAI) for
desertification. The algorism is adopted from MEDALLUS methodology as
follows;
〈br〉〈br〉
ESAI = (SQI * CQI * VQI)〈sup〉1/3〈/sup〉
〈br〉〈br〉
Where SQI is the soil quality index, CQI is the climate quality index and
VQI is the vegetation quality index. The SQI is based on rating the parent
material, slope, soil texture, and soil depth. The VQI is computed on bases
of rating three categories (i.e. erosion protection, drought resistance and
plant cover). The CQI is based on the aridity index, derived from values of
annual rainfall and potential evapotranspiration. Arc-GIS 9 software was
used for the computation and sensitivity maps production.
〈br〉〈br〉
The results show that the soil of the Nile Valley are characterized by a
moderate SQI, however the those in the interference zone are low soil
quality indexed. The dense vegetation of the valley has raised its VQI to be
good, however coastal areas are average and interference zones are low. The
maps of ESA's for desertification show that 86.1% of Egyptian territory
is classified as very sensitive areas, while 4.3% as Moderately
sensitive, and 9.6% as sensitive.
〈br〉〈br〉
It can be concluded that implementing the maps of sensitivity to
desertification is rather useful in the arid and semi arid areas as they
give more likely quantitative trend for frequency of sensitive areas. The
integration of different factors contributing to desertification sensitivity
may lead to plan a successful combating. The usage of space data and GIS
proved to be suitable tools to rely estimation and to fulfill the needed
large computational requirements. They are also useful in visualizing the
sensitivity situation of different desertification parameters.
Print ISSN:
1815-381X
Electronic ISSN:
1815-3828
Topics:
Geosciences
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