A hydrogeological conceptual model of aquifers in catchments headed by temperate glaciers

Abstract

For reliable forecasting of the evolution of critical water resources, as well as of potential flood and landslide hazards and their response to climate change, it is necessary to improve the understanding and quantification of unknown aquifer systems in glacierized catchments. We focus on four southeastern outlet glaciers of the main Icelandic ice cap, Vatnajökull. A multidisciplinary approach is carried out, including the acquisition of new in situ data to characterize aquifers and their groundwater dynamics. Moreover, the recharge to aquifers from glacial melt and effective rainfall is estimated. From a detailed analysis of all available data and the determination of the dynamic characteristics of the aquifers, a hydrogeological conceptual model of glacierized catchments is constructed: (i) two distinct aquifers, their hydraulic conductivities and their hydrodynamic responses to climate forcing are identified; (ii) a comprehensive water balance for the whole catchment is obtained; (iii) the subglacial recharge to the aquifers is shown to be 4 times higher than in the proglacial area; and (v) the importance of the impact of the glacial melt recharge on the groundwater system is demonstrated. Thus, we highlight the major role that the groundwater component has in the hydrodynamic functioning of glacierized catchments.