Interpolation of Precipitation Extremes on a Large Domain Toward IDF Curve Construction at Unmonitored Locations

Código

I-EBHE0063

Autores

Jonathan Jalbert, Luc Perreault, Christian Genest

Tema

WG 1.06: Water for biodiversity in a changing world

Resumo

Intensity-duration-frequency (IDF) curves for extreme precipitation events are widely used to design civil infrastructures like sewers and dikes. In Canada, those curves are provided by Environment Canada for every meteorological station under their authority. An important issue raised by the Canadian Standards Association concerns the sparsity of the stations network. For example, in the province of Québec, the large majority of the stations are located in the south, where most of the inhabitant lives but many important hydrological structures are located in the North. Generally, for designing purposes, the IDF curve from the closest station is used, even if it is located hundreds of kilometers away. The uncertainty according to the spatial variability of extreme precipitation is then not accounted for. The goal of the present work consists in properly interpolating the extreme precipitation of several durations to compute the IDF curves everywhere in Eastern Canada. In order to gather physical information where no observation is available, a reconstruction of the historical meteorology is used as the covariate for interpolating extreme precipitation characteristics. Such a covariate is included in a hierarchical Bayesian spatial for the extreme precipitation. This spatial model is especially suited for the covariate gridded structure, hence enabling fast and precise computations. This model provides reliable IDF curves over the whole spatial domain. Hydro-Québec, which is the principal electricity producer in the province of Québec, is now considering these IDF curves to revise their design criteria of different hydraulic structures and other assets managed by the company. We will also provide some guidance on adapting our approach to climate change.