On the statistical characteristics of drought events

Several statistical tests are performed on streamflow series for purposes of analyzing multiyear drought events. These statistical tests on both high‐flow and drought event parameters include (1) stationarity in terms of their linear trend; (2) randomness in terms of lag‐l serial correlation; (3) correlation and cross correlation between these parameters (duration, magnitude and severity). The test results and their implications are discussed in relation with the characterization of high‐flow and drought event series. Two types of envelopes for drought duration and severity are presented which use Tschebycheff's inequality. These envelopes give an excellent indication of the maximum response of a watershed in terms of drought duration and severity during the period of record.