2003): Runoff measurements and hydrological modelling for the estimation of rainfall volumes in an Alpine basin

Stream ow data and water levels in reservoirs have been collected at 30 recording sites in the Toce river basin and its surroundings, upstream of Lago Maggiore, one of the target areas of the Mesoscale Alpine Programme (MAP) experiment. These data have been used for two purposes: rstly, the veri cation of a hydrological model, forced by rain-gauge data and the output of a mesoscale meteorological model, for ood simulation and forecasting; secondly, to solve an inverse problem—to estimate rainfall volumes from the runoff data in mountain areas where the in uence of orography and the limits of actual monitoring systems prevent accurate measurement of precipitation. The methods are illustrated for 19–20 September 1999, MAP Intensive Observing Period 2b, an event with a 4-year return period for the Toce river basin. Uncertainties in the estimates of the areal rainfall volumes based on rain-gauge data and via the inverse solution are assessed