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
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. Original data have been transformed to make the time series more
An interactive app to explore world floods
The Global Streamflow Indices and Metadata Archive describes hydrological regimes all over the World. A subset of around 2000 stations over the period 1903-2016 is used in the HEGS project to study floods at the global scale. In order to
Transforming a distance matrix into a map
The map in the figure below shows the location of 195 hydrologic stations, which can be used to explore the hydrologic regimes of Australian rivers. The hydrologic regime is characterized by the flow seasonality, as shown for three particular stations
El NiñOz
The Pacific Ocean sometimes catches a fever in its Eastern tropical part (off the coasts between Central America and Peru): for extended periods of time, its surface waters are abnormally warm. These are known as El Niño episodes. Sometimes the
How Australian rivers can be grouped into 4 main hydrologic regimes
Investigating the hydrologic regime of 195 rivers in Australia revealed three types of flow seasonality. At some stations, the wettest period occurs during one particular season (winter or summer), whereas at others, similar flows are observed all year round. How
Exploring the hydrologic regime of 195 rivers in Australia
Plotting hydrologic regimes Most hydrologic studies start by determining the average quantity of water in rivers and how it is distributed throughout the year. Let’s consider the Australian reference dataset provided by the Bureau of Meteorology, with daily runoff data