Globally, at each river mouth freshwater is discharged to coastal waters. At each river mouth a freshwater plume is formed. These fresh water plumes are also known as the regions of freshwater influence (or ROFI’s). Furthermore, the freshwater plume will affect local coastal water levels. In order to improve global flood forecasting, research on this topic has been conducted. Through a combination of numerical (DFlow-fm) and probabilistic (vine copula) models predictions can be made for the size- and hydraulic effect of these river plumes.