Snowmelt Contribution to Seasonal Baseflow Dynamics in Mountain Catchments

Understanding runoff processes in mountain catchments is pivotal in hydrology. Elevated temperatures reducing snow water equivalent (SWE) significantly impact runoff dynamics and may reduce groundwater recharge. While snow is more effective in generating runoff compared to liquid precipitation, diminished snow accumulation and earlier snowmelt further exacerbate these impacts. Recent mesoscale studies challenge conventional notions of baseflow, revealing diverse landscape roles, yet linking baseflow to catchment attributes remains fragmented. This research delves into how snowmelt influences both baseflow and catchment runoff dynamics. Employing an "effect-tracking" algorithm, we analyse the distinct impacts of individual water sources, examining the variability of annual runoff. Utilizing the HBV model on a catchment scale for 59 mountain catchments located in six mountain regions in Czechia for the period 1980-2014 showed decreasing snow storage in some of the mountain regions and an overall shortening of the snow cover period. Our investigation revealed elevation-related rises in annual and summer baseflow fractions. These increases are notably heightened during periods of increased snowfall. Snow accumulation emerges as an important factor shaping baseflow dynamics, emphasizing elevation-dependent baseflow increments in snow-rich conditions. The findings not only highlight the critical influence of factors such as elevation, snowmelt, and altered snow accumulation patterns on baseflow dynamics but also underscore their broader implications. Understanding these intricate mechanisms holds promise for better water resource management and forecasting in mountainous catchments.