RESUMO
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 to 70%]. Intensive agriculture, urban expansion and industrial activity have been increasingly stressing the limited soil and water resources. In the Central Bekaa, farmers are enforced to use contaminated water to recompense water shortage during the peak crop demands. Water scarcity and mismanagement increased contagion hazards and pressure on soil and groundwater quality. The objective of this study was to provide a synopsis of the assessment methodologies and analyze the soil-groundwater vulnerability to contamination by heavy metals as based on the risks of metal transfer and the degree of protection offered by the soil cover and soil-metal interaction. The soils of the area are distinguished by a high content of clay and relatively high pH that would reduce the danger of heavy metals transfer and mobility. However, throughout the study area, the perched groundwater table is relatively high 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 low soil and groundwater table vulnerability were determined and spatially located according to international standards. Referring to the German Concept on soil protection effectiveness, the residence time of percolating water carrying soluble pollutants in the unsaturated soil zone was assessed. It varied between several months and 10 years. Zones of high soil and ground water vulnerability risk require special management to establish pollution prevention programs. Results can help land use planning oriented to the choice of suitable crops, promulgate sustainable use of natural resources and environmental preservation