Hydrology basics, episode 2: the rhythm of flood occurrences
“This was a 100-year event”. This type of sentence is often heard in the news after a flood or a storm hits somewhere, as it does a good job at carrying the rarity of what happened.
Revealing Hidden Climate Indices
In a previous post, we illustrated a widely used method called principal component analysis (PCA). This method can be used as an exploratory tool to summarise a dataset made of hundreds or thousands of time series into just a few ‘summary’ time series called principal components.
Finding hidden patterns in the data using principal components analysis
In hydrology, it is frequent to analyse long time series coming from many sites. The figure below shows monthly streamflows at 207 sites in France for the period 1969-2014.