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Mediterranean desertification and land use Project 1: core project

Exploitable results

A set of methods and procedures to create GIS raster layers that provide land managers, researchers, or consultants, with an environmental database of a given study area. The minimum input data is a Digital Elevation Model (DEM). Addition of further data is minimized by:- deriving a comprehensive set of topographic variables from the DEM;- optimizing sampling designs by applying numerical taxonomy to generate sampling strata; and 3) using spatial induction to generate layers of complex, high level variables such as vegetation or soil types. Many of the specific procedures have been developed under this Project. The whole assembly is intended to be a tool box for technicians who are not necessarily experts on the area. Procedures are objective and repeatable, and underlying assumptions are explicit. Scale of application and errors are assessed. To certain extent, the methods and procedures are independent from specific software.
These data (climate parameters, surface runoff and sediment yield) are the result of a 6 years observation period. Their processing quantifies soil erosion. Monitoring has been conducted in three areas with different' land use (area burned in 1991, abandoned grazing land, area afforested with exotic species), common to many parts of the Mediterranean, in order to assess which situation is more vulnerable to desertification processes. The results provide useful indications for land planning.
Data on physical and ecological processes in two sets of hilislopes, at the plot and first order catchment are available. They include rainfall rates, global and net radiation, air temperature and moisture, wind speed and direction, runoff, sediment and total dissolved matter discharge, soil volumetric moisture, depth of water table, plant biomass and net primary productivity, leaf area index, actual evapotranspiration. Additional parameters, such as soil characteristics, DEMS, high resolution thematic maps, and specific information about physiology of the main species are also available. These data may be useful for developing and testing models and global change research.
Land degradation in Mediterranean regions following desertification processes have attracted wide scientific attention due to its climatic, geomorphic and antropgenic consequences. However, there is relatively little empirical evidence regarding patterns of eco-geomorphic changes taking place during degradation and recovery processes. Black and white air photographs provide one of the few data sources for investigating erosion and recovery processes at a regional scale during the last 50 or 70 years. However, there are severe obstacles on their use for that purpose due to limitations on photographs viability in terms of illumination geometry and their radiometric properties. Relative calibration methods were then developed allowing for detection of significant between photographs changes. Image processing and Geographical Information (GIS) techniques were then developed for studying corresponding changes in soil erodibility and landscape fragmentation. The second research avenue was concerned with developing multi-spectral techniques for detecting soil erodibility, its bio-chemical properties and its multi-spectral reflectance distribution were assessed. A new model was then developed allowing prediction of soil erodibility potential from Landsat TM data.
Human activities in the Mediterranean basin, especially in marginal and artificial lands, increase in many cases land degradation and desertification, mainly by accelerating soil erosion from hilislopes. Combating soil erosion, using different stabilization methods is expensive and involve disturbances to the eco-geomorphological systems. The results of the present research suggest that in marginal areas, management of natural degraded areas andlor artificial non-stabilized hilislopes (such as road banks and dams) must involve means of planting of specific local shrubs in a specific spatial pattern. This method which combines local natural resource and simple planning express financial and environmental advantages as follow: high efficiency in preventing soil erosion, low expenses, friendly relationships with the environment and aesthetic contribution to the landscape.
Semi and landscapes are by definition water limited, therefore potentially sensitive to environmental change and to plant growth. The proposed study presents a methodology to define threshold soil characteristics that impose the change of the present land use. A dominant soil characteristic that reflects the potential land use is soil depth. The terms crucial and critical soil depths are introduced for the determination of the ability of a land resource to sustain a certain land use. The methodology of threshold soil characteristics can be used for land use planning and remove agricultural land for protection of the environment.
Within the work carded out in MEDALUS projects a database was created, that contains data on soil erosion, vegetation and climate of a field site in Greece (Spata). The database contains data from 1991-1999 on; - climate such as dry and wet temperature, soil temperature, precipitation, evaporation, relative humidity, solar radiation, net radiation, wind speed, wind direction, - soil erosion such as water runoff and sediment loss measurements under different land use types of the same area, - soil such as soil characteristic properties, soil moisture content, - vegetation such as vegetation cover, biomass production, growth rate, species composition. This database can be used for control and prediction of desertification through modelling development.
This is the basic field data collected by the partners during the duration of this project and earlier ones. The data and information documents the changing conditions at key sites across southern Europe from Portugal to Israel where desertification relevant biophysical data have been measured. The data and information is a unique resource collected according to commom protocols and could be used for various scientific or business purposes. One way of applying it is through the functional approach described for topics that form part of Medalus Project 2.
The GIS-based evaluation model deals with the impact of mechanical practices for the creation and management of pastures (tillages. stone and brush removal. seeding), and classifies the land into five land suitability classes as defined in the Guidelines of Land Evaluation (highly suitable. moderately suitable. marginally suitable. currently not suitable, permanently. unsuitable). The model can be a useful tool for land planning and management in agropastoral regions of the Mediterranean basin, especially where agropastoral environments have been subjected to complex land use changes leading to both land abandonment and to local increases in agropastoral pressure in unsuitable areas. These dynamics often cause widespread land degradation phenomena. The main innovative aspect is the use of information deriving from different layers (land cover. soil. aspect. slope, elevation) allowing the maximization of available information. This constitutes an alternative approach to the FAO Framework for Land evaluation (1976) based on the identification of land units to which a suitability class is assigned. From an operational point of view, the parametric approach proposed bypasses the problems related to the limiting , pa factor approach often used in land evaluation. With the proposed model the cumulative suitability index is always a weighted average of all variable values. Further more GIS technology, allows the application of the model at regional scale. The model has been successfully, and applied to the Baronic Region. over an area of about 2 1,000 ha. The results obtained are contributing to the implementation of a land conservation programme.
The MEDRUSH model is a forecasting model for hydrology, soil erosion and sediment yield in catchments of up to 2000 km'. The model is designed to be set up, as far, as possible, with existing or readily available data. Its main purpose is to provide estimates of changes in water and sediment yield and loss, both at whole catchment and sub-catchment scale within an area of up to 2000 kM2, in areas subject to global changes through climate or land use change. It therefore contains components which explicitly forecast changes in vegetation cover and soil properties which are relevant over periods of decades. Validation of the model is largely internal, with respect to the operation of the component sub-models for evapotranspiration, runoff, vegetation growth and soil erosion. The model has been produced as a collaboration of Leeds, Newcastle and Sheffield, and has been applied to all or parts of the Guadalentin (SE Spain), Agri (Basilicata) and to 2 small catchments in Hungary, in collaboration with other named partners above. For each application, it is recommended that potential users collaborate with the Leeds group in setting up and applying the model, as code is still available primarily as a research tool rather than as commercially developed software.
The results have been collected during 3 years of studies. The research had the purpose of identify indicators of desertification in different areas establishing relationships with land resources management, and to study and map environmentally sensitive areas. Studies has been carried out in urbanized and rural areas, in mining and industrial areas, in semi-natural and agricultural-wooded areas, investigating irrational agricultural practices, degradation in common land, soils consumption due to urbanization, heavy metal contamination of soils and water in mining areas, state of preservation of soils and vegetation on karst areas, effects of exotic tree plantations on soil degradation, causes and processes of degradation in cork-oak forests. These results enable to evaluate the onset and or trend of desertification processes in the different realities considered , and are useful to drawing up guidelines for strategies aimed at combating the phenomenon.

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