Are kettle lakes good objects to observe groundwater recharge?

English Abstract:

It is known that the mean total annual volume of lacustrine groundwater discharge is closed to the mean total annual groundwater recharge in the whole catchment. All of hydrological interactions are not linear but the signal observed in lakes can be linked to recharge if lakes connections to groundwater are clearly determined. In Canada, the fractionated melting of the Laurentide ice sheet allowed the formation of kettle lakes. These lakes can be either (i) completely disconnected from groundwater, behaving like large rain gauges, or (ii) in direct connection with the underlying aquifer, being thus a opened window on groundwater. Twenty kettle lakes distributed in South Quebec were sampled in June-July and October-November 2014, and their water balances determined by using geochemical tracers. Those balances in conjunction with stable isotope signatures of system end-members allow the determination of the sensibility of lake water budgets regarding all components and thus groundwater discharge. It appears that some lakes can be very sensitive to change in groundwater-lake interactions. The seasonal response of water balance was also analysed to discuss groundwater-lake interaction dynamics and links between recharge dynamics. From these results a sensitive analyse of water budget parameters allow to discuss if kettle lakes may be sensitive systems to monitor recharge changes at the catchment scale.