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Mediterranean Land Degradation: its problems and its cures
Mediteranean land degradation is a severe threat to the landscapes of the Mediterranean countries. Land degradation is often caused by mismanagement of land and water resources and expresses itself by processes such as soil erosion, soil surface crusting, forest fires and/or impoverishment of the vegetation. An ever increasing pressure due to tourism, a growing water consumption by agriculture and tourism and a growing mechanization of the agricultural practices stimulate land degradation. Examples of degraded landscapes are given in the following pictures.
 Gully System in the Ardèche Province, France. |
 A gully landscape due to soil erosion in the Guadelantin near Lorca, south-eastern, Spain. |
The DeMon project, financially supported by the European Union (DGXII: Environment), is developing methods to monitor and to model Mediterranean land degradation processes. Remote Sensing techniques (digital images collected by satellites and aircrafts) and Geographical Information Systems play a key role in these procedures. Computer simulation of degradation processes increase our understanding of the process. Understanding the process is essential to take effective counter measures. The DeMon project is currently in its second phase. The first phase, DeMon-1 (1992-1995), focussed on the experimental development of monitoring and modelling methods. The second phase, DeMon-2 (1996-1999) aims at refining the earlier developed methods.
The Main DeMon-2 Topics at Utrecht (1996-1999):
1. Eco-zoning of the European Union Part of the Mediterranean Region
Study Site: the European Union part of the Mediterranean Basin
In order to assess the degree of degradation of the land for the entire European part of the
Mediterranean region, a physiographic zonation of this area is proposed. The area is stratified
into homogeneous zones with regard to climate, lithology and edaphic characteristics.
The current stage of the research is that longterm meteorological data were collected for 275
stations scattered over the Mediterranean region. This huge dataset is now analysed in terms
of rainfall agressiveness and rainfall irregularities. The next will be that these meteorological
data are linked to a geographic database in a GIS to combine the meteorological data with
elevation data and soil type information. An example of the first efforts to build such a GIS database
is shown in the following figure, it shows the average annual precipitation for approximately 350
meteorological stations scattered over southern Europe.
Average annual precipitation as measured at meteorological stations
located in the mediterranean countries of the European Union.
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2. Biomass Deficit as an Indicator for
Degradation
Study Site: La Peyne catchment, southern France. |
3. Soil Erosion Modelling using the SEMMED model
Study Site: La Peyne catchment, southern France.
In the DeMon-1 project the soil erosion model SEMMED (Soil Erosion Model for
MEDiterranean regions) was developed in the former test site Ardèche, France. In the
DeMon-2 phase the model will be refined and applied to the La Peyne test site. SEMMED
comprises several modules, each of which describes a part of the erosion process such as
soil particle detachment, moisture storage in the top soil and transport of soil particles by
overland flow. SEMMED uses (multi-temporal) Landsat TM images to account for
vegetation properties and it uses a digital terrain model in a GIS to account for
topographical properties. Spectral vegetation indices allow a pixel-by-pixel assessment of
vegetation properties and the multi-temporal approach enables the assessment of the change
of vegetative cover in one growing period. The current status of this part of the project is
that input data for SEMMED of the La Peyne site is now collected and a field campaign is
scheduled for June 1997.
Flowchart of the SEMMED model:
In each of the three research topics, 4th year students in Physical Geography participate in the field work, the laboratory analyses, the satellite images processing and in the integration of the various data sources. A Geographical Information System, a software package to process and analyze maps in digital form, play a key role in the final analyses.
The DeMon project is concentrating its research on three European Mediterranean sites with varying degradation processes:
The location of the research areas of the DeMon project.
1. Guadalantin, Spain.
2. La Peyne, France
3. Asteroussia, Crete
Or Send your mail to:
s.dejong@geog.uu.nl
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