Top-kriging interpolation for stream flow extremes estimation in ungauged catchments

The top-kriging interpolation technique is applied over the geographical space of Tuscany Region, in Central Italy, on a territory of about 23.000 km2. The analysis is carried out on the discharge data of 50 consistent hydrometric stations, recorded from 1923 to 2011. The results are validated using a cross-validation procedure. A multivariate regression technique and a classical interpolation technique, i.e. the ordinary kriging, are also used to assess the proposed methodology. With the aim to define the most suitable procedure for streamflow extremes regionalization, the results are compared through different error measurement methods (mean square error, mean relative error, etc.).