The hydrological response of melting ephemeral snowpacks compared to winter rainfall events in a mid-mountainous Pyrenean catchment

Abstract

AbstractThe hydrological role of ephemeral snowpacks and their differences in stormflow and sediment transport characteristics compared to events triggered by winter rainfall conditions have received limited attention. This study aims to analyze the hydrological and sediment transport responses to rain-on-snow (ROS), melt, mixed, and rainfall events in the Araguás Catchment, situated in a mid-mountain site of the Central Spanish Pyrenees, with a climate strongly influenced by Mediterranean conditions. This catchment represents the transition from a winter ephemeral snow environment to a fully rainfall-dominated site. Results indicate that snowmelt has a modest yet measurable impact on the annual water balance, averaging 10% and rising to 30% during winter (December to February). ROS and melt events consistently exhibited higher mean and maximum discharge and elevated stormflow coefficients compared to mixed and rainfall events. The lowest water infiltration into the soil was observed during melt events, attributed to the potential for frequent freezing soils, specific poor edaphic conditions, and the rapid snowmelt in the area. Consequently, melting events displayed the shortest flood hydrographs among the four analyzed events. The study also underscores precipitation’s almost negligible erodibility capacity in the solid phase and emphasizes the protective role of snow cover in preventing soil erosion. It is important to note that the presented results are significantly influenced by the physiographic, lithological, and edaphic characteristics of the Araguás Catchment. This highlights the importance of conducting more detailed analyses of ephemeral snowpacks in experimental sites under a broader range of environmental conditions for a comprehensive understanding.