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Abstract

Climate change is increasing the magnitude and frequency of extreme hydrological phenomena, such as droughts and floods, throughout the planet. Given its geographic characteristics, Chile is one of the most vulnerable countries in the world to climate change. Observed rainfall and river flow series show statistically significant trends of change and a notable non-stationarity. Given the above, the assumption of stationarity of the series widely used in the estimation of peak flows with different return periods, would no longer be fulfilled. The objective of this work is to evaluate if there are significant differences in peak flow values obtained for different return periods when using the classical statistical method (steady state) and methods that consider the non-stationarity of these. For this purpose, 14 representative stations located between the Maule Region and the Araucanía Region will be analyzed. Stations were selected considering a record of more than 30 years of data, in addition to presenting a positive and significant trend in the series of maximum flows.The study area includes characteristics of Mediterranean and temperate climates of the south, which is determined by a variation in the pluviometry regimes with an increase in precipitation from north to south. The results, when estimating peak flows with different return periods, show that for 50% of the stations analyzed there is a statistically significant difference between the application of statistical methods that consider a stationary versus non-stationary state, expressed in p-values less than 0.025.