干旱区生态环境知识资源中心

One of the most acute problems facing water resources in semi-arid regions is the ongoing salinization of groundwater. The example discussed in the paper is from the Coastal Plain aquifer of Israel where most attention has been given until recently to salinization due to seawater encroachment. The present study revealed that large amounts of salt have been added to this aquifer along its eastern boundary which is in close proximity to a syncline filled by Tertiary chalks and marl. The saline water is characterized by high tritium levels and a stable isotope composition which differs from that of local rains. It is suggested that intensive irrigation with water imported from the Sea of Galilee induced flow in old fractures and in solution channels developed in the underlying chalks. These channels are filled with soluble salts which accumulated during the Holocene in the Tertiary aquitard and were mobilized as a result of increased irrigation of overlying soils. The soluble salts reached groundwater and ultimately flowed into the adjacent sandy Coastal Plain aquifer. Overpumping of the Coastal Plain aquifer caused continuous lowering of the groundwater table enhancing flow and considerable transport of solutes from the adjacent aquitard.