ABSTRACT
Water is a mobile medium within any landscape, and, as such, it comes into contact with many parts of a catchment that do not themselves directly interact with one another, for instance humus and till, or the atmosphere and buried bedrock. Thus, one of the most fundamental driving mechanisms for geochemical and hydrological processes in a catchment is the global water cycle: precipitation, which falls as rain, snow, fog, etc., is partly evaporated, partly stored in living organisms and soil, partly recharged into the groundwater, and partly transferred to surface water streams by surface runoff. Areas along the stream bed often are natural discharge zones for groundwater, as are the occasional springs and seeps within the catchment. Groundwater movement in such zones has a vertical upward component. Because all infiltrated water must at some point resurface, and because discharge areas commonly are much smaller than recharge areas, groundwater flows vigorously out of the soil in discharge zones.
