The Role of Snowmelt on the Spatio-Temporal Variability of Spring Recharge in a Dolomitic Mountain Group, Italian Alps

Abstract

Springs play a key role in the hydrology of mountain catchments and their water supply has a considerable impact on regional livelihood, biodiversity, tourism, and power generation. However, there is still limited knowledge of how rain and snow contribute to the recharge of Alpine springs. This study presents a four-year investigation of stable isotopes in precipitation and spring water at the scale of a 240 km2 wide dolomitic massif (Dolomites, Italian Alps) with the aim of determining the proportions of snowmelt and rain in spring water and to provide insights on the variability of these contributions in space and time. Four precipitation sampling devices were installed along a strong elevation gradient (from 725 to 2660 m a.s.l.) and nine major springs were monitored seasonally. The monitoring period comprised three extreme weather conditions, i.e., an exceptional snowpack melting period following the highest snowfall in 30 years, an intense precipitation event (386.4 mm of rain in 48 hours), and one of the driest periods ever observed in the region. Isotope-based mixing analysis revealed that rain and snowmelt contributions to spring water were noticeably variable, with two main recharge time windows: a late spring–summer snowmelt recharge period with an average snowmelt fraction in spring water up to 94 ± 9%, and a late autumn–early winter period with a rain fraction in spring water up to 68 ± 17%. Overall, during the monitoring period, snowmelt produced high-flow conditions and sustained baseflow more than rain. We argue that the seasonal variability of the snowmelt and rain fractions during the monitoring period reflects the relatively rapid and climate-dependent storage processes occurring in the aquifer. Our results also showed that snowmelt fractions in spring water vary in space around the mountain group as a function of the elevation of their recharge areas. High-altitude recharge areas, above 2500 m a.s.l., are characterized by a predominance of the snowmelt fraction (72% ± 29%) over the rain contribution. Recharge altitudes of approximately 2400 m a.s.l. also show a snow predominance (65 ± 31%), while springs recharged below 2000 m a.s.l. are recharged mostly from rain (snowmelt fraction of 46 ± 26%). Results from this study may be used to develop more accurate water management strategies in mountain catchments and to cope with future climate-change predictions that indicate a decline in the snow volume and duration in Alpine regions.

Hydrometeorological factors determining the development of water table cave patterns in high alpine zones. The Ordesa and Monte Perdido National Park, NE Spain

“…The recharge variations depend on the infiltration rate of the meteoric water. In high mountain zones, the proportion of snowmelt and rainfall integrating the aquifer recharge highly depends on the elevation of the recharge zone (Lucianetti et al, 2020). In the recharge zone of the Garcés karst system, the snowmelt flows diffusely through the snowpack, minimizing surface runoff.…”

Variation Characteristics of Stable Isotopes in Precipitation and Response to Regional Climate Conditions during Pre-monsoon, Monsoon and Post-monsoon Periods in the Tianshui Area

“…Affected by ground weather conditions, different regions have local meteoric water lines (LMWL) that reflect their precipitation patterns. Analyzing the local meteoric water line can provide a reference for the study of the local water cycle process [33][34][35].…”

Studying the dynamic of a high alpine catchment based on multiple natural tracers

“…Existing field-based studies can be classified according to their focus: i) understanding dominant runoff generation mechanisms during rainfall and snowmelt events (Penna et al, 2016;Engel et al, 2016), including small-scale studies of snowpack flow paths (Webb et al, 2020), ii) understanding the origin of winter low flow (Floriancic et al, 2018), iii) quantification of groundwater or spring recharge (Lucianetti et al, 2020) and seasonal groundwater storage (Arnoux et al, 2020) or iv) understanding the role of glaciers and rock-glaciers in the hydrological response of high elevation catchments (Brighenti et al, 2019;Zuecco et al, 2019;Ohlanders et al, 2013;Penna et al, 2014). A common feature of these studies is the use of natural tracers, such as electric conductivity and/or stable isotope composition of water, for example, to gain new insights into the fate of rainfall and snowfall and related water flow paths and to formulate hypotheses about dominant runoff drivers at specific times of the year, or about the hydrologic response of selected landscape units.…”