Hydrogeological Issues of Riverbank Filtration — A Review

Engineers and scientists are faced with the problem of the behavior and fate of contaminants during the infiltration of river waters to groundwater. Sontheimer [1], e.g., found that induced bank filtration resulted in the elimination of some of the contaminants and could thus be considered as the first treatment step for the production of drinking water from river water. If rivers that naturally lose water to aquifers are contaminated, e.g., from outlets of sewage treatment plants, then the groundwater may become contaminated, too (e.g., Schwarzenbach et al. [2]). The quality of the water, which is freshly infiltrated from the river, revealed to be strongly dependent on the residence time and the mixing rate of river water and deeper groundwater. In a few infiltration systems, some contaminant compounds could partly be eliminated from the aquatic environment, and the quality of river water has somewhat improved (e.g., von Gunten and Lienert [3]). Today’s concerns are broader than looking at the water quality. The state of the groundwater/surface water ecosystem and its evolution in the future is of interest. In many floodplains, the state of riverbeds and banks is far from being natural (e.g., Brunke and Gonser [4]; Bencala [5]). Various forms of land use, such as hydropower generation, flood prevention, or the need of arable land, require a safe and defined bank line and a channeled riverbed. These requirements are in conflict with the needs of the vegetation and animals at the bank and in the bed of rivers (riparian zone).