Multivariate probabilistic characterization of drought events

In the present study a methodology for the analytical derivation of the multivariate cumulative probability distribution (cdf) of drought characteristics based on the stochastic structure of the underlying water supply series and a threshold describing the water demand level is presented. The derived cdf’s are then applied to determine the return period of critical droughts by considering jointly two characteristics, e.g. droughts with accumulated deficit greater than a given value and fixed duration. By considering different combinations of drought characteristics, several types of critical droughts can be identified.