Snow Cover Area and Snow Water Equivalent Relation in Estonia to Model Surface Water-Groundwater Interactions

Hydrological processes, especially snowmelt-related ones, are crucial in water resource management in cold climate regions. Process-based hydrological models, such as the Precipitation-Runoff Modeling System (PRMS), commonly utilize snow depletion curves to describe snowmelt dynamics. Understanding the seasonal variability of snowmelt processes and accurately simulating them through models is essential for assessing water resource sensitivity to various environmental changes in our climate. This study elucidates the relationship between normalized snow water equivalent (SWE) and snow cover area (SCA) in Estonia, northeastern Europe. The snow depletion curves were constructed for 40 gauged river catchments using SWE measurements from the eleven meteorological stations throughout Estonia and SCA data derived from Sentinel-1 and Sentinel-2 satellite imagery from 2016–2022. The resulting snow depletion curve provides valuable insights into the connection between SWE and SCA, allowing for estimating snow water equivalent using remote sensing data in regions lacking on-site measurements. This approach enables the assessment of snowmelt processes in these areas, contributing to improved streamflow and groundwater level forecasts through hydro(geo)logical models. Ultimately, integrating remotely sensed and in-situ data enhances our ability to understand and model the complex interactions between surface water and groundwater at regional and local scales. This research contributes to advancing the field of hydrology and supports informed water resource management decisions.