Complex high- and low-flow networks differ in their spatial correlation characteristics, drivers, and changes

However, these spatial relationships in high and low flows are often overlooked in risk assessments and we know little about their differences and origins. Here, we ask how spatial relationships of both types of hydrologic extremes and their potential hydro-meteorological drivers differ and vary by season.

We propose lagged upper- and lower-tail correlation as a measure of extremal dependence for temporally ordered events to build complex networks of high and low flows. We compare complex networks of overall, low and high flows, determine hydro-meteorological drivers of these networks, and map past changes in spatial relationships using a large-sample data set in Central Europe. Our network comparison shows that low flows are correlated more strongly and over longer distances than high flows and high- and low-flow networks are strongest in spring and weakest in summer.