water Article Introducing Non-Stationarity Into the Development of Intensity-Duration-Frequency Curves under a Changing Climate Daniele Feitoza Silva 1,* , Slobodan P. Simonovic 2,3 , Andre Schardong 2,3 and Joel Avruch Goldenfum 1 1 Institute of Hydraulic Research (IPH), Federal University of Rio Grande do Sul, Porto Alegre, RS 15029, Brazil;
[email protected] 2 Department of Civil and Environmental Engineering, Western University, London, ON N6G 1G8, Canada;
[email protected] (S.P.S.);
[email protected] (A.S.) 3 Institute for Catastrophic Loss Reduction, Toronto, ON M5C 2R9, Canada * Correspondence:
[email protected]; Tel.: +55-51-982-104-261 Abstract: Intensity-duration-frequency (IDF) relationships are traditional tools in water infrastructure planning and design. IDFs are developed under a stationarity assumption which may not be realistic, neither in the present nor in the future, under a changing climatic condition. This paper introduces a framework for generating non-stationary IDFs under climate change, assuming that probability of occurrence of quantiles changes over time. Using Extreme Value Theory, eight trend combinations in Generalized Extreme Value (GEV) parameters using time as covariate are compared with a stationary GEV, to identify the best alternative. Additionally, a modified Equidistance Quantile Matching (EQMNS) method is implemented to develop IDFs for future conditions, introducing non-stationarity Citation: Silva, D.F.; Simonovic, S.P.; where justified, based on the Global Climate Models (GCM). The methodology is applied for Moncton Schardong, A.; Goldenfum, J.A. and Shearwater gauges in Northeast Canada. From the results, it is observed that EQMNS is able Introducing Non-Stationarity Into the to capture the trends in the present and to translate them to estimated future rainfall intensities.