Predicting peakflows in mountain river basins and data-scarce areas: a case study in northeastern Italy

We present a procedure to predict peakflows in mountain and ungauged basins, by addressing two challenges: fine temporal-resolution required to capture intense storms; scarcity of streamflow measurements needed to calibrate hydrological models. The study area is the Fella river basin at Pontebba and its upstream Uque sub-basin, northeastern Italian Julian-Alps. A non-stationary hydraulic model is combined with field measurements to derive rating curves at the downstream outlet which lacks discharge data. 5-minute rainfall series are exploited to predict hydrographs through a semi-distributed hydrological model, at continuous and event scales. The hydrological modelling on an ungauged basin is verified at the inner upstream outlet. Results indicated that the predictability of intense events is improved when a single storm is evaluated compared to a continuous hydrograph; event-based hydrographs at upstream outlet are well reproduced by the model calibrated with downstream data, thus allowing the use of the parameters in an ungauged basin.