To assess the potential of remote sensing techniques and GIS for
the purpose of studying, monitoring, and possibly controlling the
dynamics of desertification in the Mediterranean area and as well
to close the "scale gap" between site experiments of energy and
water exchange at the earth surface, and the desertification
processes taking place at national to regional levels.
The basis of the work is aiming to relate satellite data to the
characteristics of desertification on the ground, particulary
those related to vegetation degradation and soil erosion
To monitor energy and water budgets including actual
evapotranspiration METEOSAT and NOAA satellites will be used.
METEOSAT data (5 km resolution) will firstly be used to combine
cloud information and rain gauge data in order to produce
precipitation (P) maps and secondly to combine surface visible
and thermal data for the mapping of actual evapotranspiration
(ETa) using an energy balance approach which will also permit
derive the net radiation (In). These three important
of the energy and water budget will enable the derivation of some
important desertification parameters like the dryness ratio (DR
= In/P); desertification index (DI = In/ETa).
NOAA satellite data, with a higher spatial (1 km) and radiometric
resolution, will also be used to map In and ETa by means of
a suitable algorithm .
The results obtained from the METEOSAT and NOAA satellite will
be compared mutually and with ground data from HAPEX-Spain and
existing national meteorological and hydrological measuring
networks (rainfall, radiation and river run-off).
The actual evapotranspiration data will be validated at the level
of catchments, using the water balance .
To monitor the vegetation cover NDVI or similar indices will be
calculated using NOAA data. Ground observations of the vegetation
as well as LANDSAT TM derived vegetation and erosion maps, will
be related to it.
For groundthruth and field surveys assessing the state of
desertification, three test sites corresponding to a quarter
LANDSAT scene will be chosen in three different climatic zones
with different degrees of land degradation. Satellite data will
be studied for a dry and wet season. Hydrometeorological data as
well as other data relevant for the study areas will be collected
Satellite derived data, groundtruth data and other existing data
will be integrated in a Geo Information System (GIS) for final
analysis and synthesis. The GIS will also serve as prototype of
a "Desertification Information System" (DIS). To this end
indicative maps of desertification problems will be produced for
the test areas, the Iberian peninsula and the Mediterranean
Funding SchemeCSC - Cost-sharing contracts
7500 AA Enschede
6701 AP Wageningen
3730 AE De Bilt