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Water balance in Alpine catchments by Sentinel data
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  • Roberta Perico,
  • Philip Brunner,
  • Paolo Frattini,
  • Giovanni Battista Crosta
Roberta Perico
University of Milano-Bicocca

Corresponding Author:r.perico@campus.unimib.it

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Philip Brunner
University of Neuchatel
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Paolo Frattini
Universita' degli Studi di Milano - Bicocca
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Giovanni Battista Crosta
Università degli studi di Milano Bicocca
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Attaining a comprehensive and reliable water balance of snow-dominated alpine catchments is fundamental for a holistic representation of the hydrological and hydrogeological processes. A major limitation to the elaboration of this balance in alpine terrain is the difficultly of data acquisition as well as the limited presence of meteorological stations. Remotely sensed data can provide valuable information for the balance elaboration at a regional scale. We exploited Sentinel-satellite data to estimate the groundwater storage for one hydrologic year in an extensive Alpine catchment located in northern Italy. Evapotranspiration (ET) and Snow Water Equivalent (SWE) were estimated once weekly with the combined use of Sentinel data, at a spatial resolution of 20 m and 30 m, respectively. Finally, the groundwater storage was estimated by means of the residual water balance approach. The results show that the adopted satellite-based methods allow obtaining consistent and physically realistic values to describe the groundwater storage dynamics, with a relatively low uncertainty (36%). For the studied hydrologic year, a positive storage occurred only in the snowmelt period and the overall storage was negative, leading to a lowering of the groundwater level in the floodplain. In addition, the influence of physiographic parameters (altitude, slope, and aspect) and the seasonal conditions on the estimates of ET and snow-depth were investigated. For SWE estimates, an altitude-dependent effect and a lower accuracy in the snowmelt phase were observed. Finally, the estimated values of ET and the SWE-linked components were verified for a gauged tributary valley with negligible groundwater storage.