1 23 Hydrogeology Journal Official Journal of the International Association of Hydrogeologists ISSN 1431-2174 Hydrogeol J DOI 10.1007/s10040-012-0909-4 Impact of permafrost development on groundwater flow patterns: a numerical study considering freezing cycles on a two- dimensional vertical cut through a generic river-plain system Christophe Grenier, Damien Régnier, Emmanuel Mouche, Hakim Benabderrahmane, François Costard & Philippe Davy