Effect of snowmelt on the dynamics, isotopic and chemical composition of runoff in mature and regenerated forested catchments

Using isotopic and hydrochemical tools, we focused our study on water and element fluxes with snowmelt in two headwater catchments with different forest stands. One catchment is with mature, and the other catchment is with forest regenerating after a tree dieback. Sampling and analysis of the surface water and precipitation throughout one hydrological year, and of snowpack in snow season, enabled us to estimate the isotopic balance and chemical snowpack evolution, but also the snowmelt contribution to inlets and outlets of lakes. Stable isotope values varied from snowpack formation to snowmelt with delta H-2 amplitudes of -25 parts per thousand in the mature and -17 parts per thousand in the regenerating forest catchments over the duration of the snowpack persistence. The mature forest had one month longer duration of snow cover and higher concentration of solutes in the throughfall and snowpack. In both catchments, heavier isotopes of the water molecule (O-18 and H-2) preferentially left the snowpack, which stored considerable amount of rainwater and snowmelt. This resulted in heavy isotopes depletion in the end of the spring snowmelt. Ions were also eluted from the snowpack during rain events and partial snow melting throughout the winter, causing fluxes of diluted water at the end of the snowmelt. Our results demonstrate the hydrological and hydrochemical variability of the snowpack, which in the future may even increase with rising temperatures and changes of precipitation patterns.

Automated summary

Using isotopic and hydrochemical tools, this study focused on water and element fluxes with snowmelt in different forest stands. The research found fluctuations in isotopic values in different forest catchments, and highlighted the impact of stored rainwater and snowmelt in the snowpack on water isotopes.