On the joint use of SAR and meteo-climatological information to monitor the Po River under nominal and drought conditions

This study addresses the drought phenomenon that affected the Po River, north of Italy, by jointly exploiting methods based on measurements remotely sensed by the European Sentinel-1 C-band Synthetic Aperture Radar (SAR) and meteo-climatological information derived from both in situ and satellite datasets. The SAR methods consist of a baseline approach, which estimates the water-covered area from dual-polarized SAR imagery using a constant false alarm rate (CFAR) approach, augmented with ancillary vertical ground displacement information derived from SAR interferometry (InSAR). The meteo-climatological information includes hydrometric water level, rainfall data, and the Standard Precipitation Evapotranspiration Index (SPEI). Experimental results, obtained using a seven-year time series of SAR scenes collected over the Po River close to the city of Piacenza and contrasted with ancillary external information, demonstrate the soundness of the proposed SAR-based added-value products and their satisfactory accuracy in emphasizing both seasonal trends and the drought phenomena occurred in the area. This paves the way for an operational use of SAR measurements to monitor the water-covered area of the Po River and potentially other similar environments.