Regional Frequency Analysis of extremes flows in Northern of Spain

This paper presents a study of regional frequency analysis of peak flows in Cantabrian and North Atlantic basins of Spain, based on the index-flood procedure with estimated parameters by L-moments approach (Hosking and Wallis, 1997). Observed annual maximum flow series of 85 gauged catchment areas in natural regime with records from 15 to 72 years were analyzed. The discordancy and heterogeneity measures based on the L-moments suggest 9 statistical homogeneous regions in which the same frequency distribution function is shared except for a scale factor. The main contribution of the study is the distinction of the regions according to their pluvial or snow character and the model capacity to estimate extreme peak flows with greater robustness than other methodologies.