Morphological and hydrogeological controls of groundwater flows and water age distribution in mountain aquifers and streams

Mountainous regions encompass a substantial portion of the Earth's landmass, spanning a variety of latitudes and climates. They hold the source of the hydrological cycle, supplying high-quality water to the floodplains downstream, where the majority of the human population dwells. Mountains generate a notably large amount of water compared to surrounding floodplains, and their capacity to store large volumes of water for extended periods is crucial for mitigating climatic variability and providing downstream ecosystems with persistent water resources. Traditionally, hydrological research in mountains has focused on surface and shallow processes, neglecting the role of deep-seated rock formations. However, recent field studies have revealed that fractured rock formations are ubiquitous and, despite their low permeability, can harbor aquifers and groundwater flow systems. Nonetheless, it is still unclear how deep subsurface flows interact with the overall hydrological functioning of mountain areas, how significant is their contribution in the long-term water budgets, and how they are jointly controlled by critical climatic, morphological and geological factors. These questions are here investigated with a simplified, yet effective, numerical conceptualization of mountain reliefs retaining the most relevant hydrogeological processes controlling water storage and transfer in the mountain environment. New insights are provided on, for example: i) how geomorphoclimatic factors modulate the contrasting ages and amounts of subsurface flows as compared to streamflows; ii) how much water can be stored in mountain aquifers and how sensitive it can be to climatic alterations; iii) how climate change can impact the extent of the permanently active drainage network under different morphological and geological settings. This study aims to provide a systematic view on the coupled hydrological and hydrogeological functioning of mountain regions and can ultimately help in quantifying the susceptibility of this precious environment to climate change and water use.

BETTERLE Andrea;  BELLIN Alberto; 

2024-12-13

AMER GEOPHYSICAL UNION

JRC136954

0043-1397 (online),   

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2024WR037407,    https://publications.jrc.ec.europa.eu/repository/handle/JRC136954,   

10.1029/2024WR037407 (online),