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Salinization refers to the accumulation of easily dissolved salts in the water unsaturated soil. These salts are derived from brackish/saline groundwater and irrigation water and pose a problem, in particular if leaching of salts to ground water is limited or prevented due to e.g. large evapotranspiration and shallow groundwater levels. Associated problems relate to the composition of salts (Bresler et al., 1982). Salinity poses problems in many Mediterranean countries (Spain, Portugal, S.-France, Italy, Greece, Balkan countries) and is expected to increase if climate changes due to larger extremes in droughts and rainfall. Sodification is somewhat more restricted as it only occurs if sodium (Na) is the dominant cation and for loamy/clayey soils, but is a major problem in semi-humid/semi-arid Europe. The Carpathian Basin and several South-East European alluvial plains have large areas of sodic soils that are unsuitable for agriculture. Due to their poor structure, soil surface processes and shallow groundwater are in poor hydrological contact. This opposes natural regeneration of such soils, whereas active remediation is very costly, if at all possible. However, also in regions with sea water intrusion (coastal plains, as in France, Netherlands, Belgium), agriculture is only feasible if a delicate balance is maintained between fresh water lenses, and the brackish ground water on which they float. Decreasing river water flow and sea water level rise, both caused by climate change, worsen the situation and require the investigation of adaptation management options (NEAA/NMP, 2005; Metzger, 2005).
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