Discharge assessment in ungauged river sites by using satellite altimetry data: the case study of the Po River (Italy)

River discharge estimate at ungauged sites is addressed by using water level data acquired by radar altimeter which represent the input for the Rating Curve Model (RCM). This simple approach is able to assess discharge at a downstream section where only stage is monitored while the flow is recorded at an upstream site and significant lateral inflows can occur along the branch. The analysis is done for a reach of the Po River (northern Italy) using both mimicked and actual altimetry satellite data. Results show that RCM provides accurate discharge estimates when the flow is in the main channel, while underestimation occurs when it spills to the floodplains for an erroneous assessment of the upstream effective flow area. The proposed procedure is appealing for river sites when hydrometric information are absent or limited to low flow, as it might occur in the most of the developing countries