Scope

Abstract

Ground water originates from the infiltration of atmospheric precipitation and, where a landward gradient of the water table occurs, of surface water, too. After flowing underground for varying distances it feeds the surface water systems, rivers and lakes. Only a small proportion flows directly into the sea or evaporates where the water table comes close to the ground surface. During its movement from the surface of the ground through the soil, the water-unsaturated and the water-saturated zone to the points where it re-emerges, water is subject to numerous interactions between the aqueous and the solid phases through physical, chemical and microbial processes such as dissolution, precipitation, oxidation and reduction, complexation, ad-and desorption, filtration, gas exchange, evaporation, biological metabolism, isotopic redistribution and anthropogenic influences, which lend it its typical properties.