مرکز منطقه ای اطلاع رساني علوم و فناوري - PRELIMINARY CONTAMINATION HAZARDASSESSMENT OF LAND RESOURCES INCENTRAL BEKAA PLAIN OF LEBANON

Abstract :

The Central Bekaa plain constitutes the main region with prime agricultural land in Lebanon. The agricultural sector is the main consumer of available water resources (up to70%). Intensive agriculture, urban expansion and industrial activity have been increasinglystressing the limited soil and water resources. In the Central Bekaa, farmers are enforced touse contaminated water to recompense water shortage during the peak crop demands. Waterscarcity and mismanagement increased contagion hazards and pressure on soil andgroundwater quality. The objective of this study was to provide a synopsis of the assessmentmethodologies and analyze the soil-groundwater vulnerability to contamination by heavymetals as based on the risks of metal transfer and the degree of protection offered by the soilcover and soil-metal interaction. The soils of the area are distinguished by a high content ofclay and relatively high pH that would reduce the danger of heavy metals transfer andmobility. However, throughout the study area, the perched groundwater table is relativelyhigh with a depth varying between 60 and 500 cm making it highly vulnerable to pollution.Metals might be more mobile under reducing conditions. The area of high, medium and lowsoil and groundwater table vulnerability were determined and spatially located according tointernational standards. Referring to the German Concept on soil protection effectiveness, theresidence time of percolating water carrying soluble pollutants in the unsaturated soil zonewas assessed. It varied between several months and 10 years. Zones of high soil and groundwater vulnerability risk require special management to establish pollution preventionprograms. Results can help land use planning oriented to the choice of suitable crops,promulgate sustainable use of natural resources and environmental preservation.