RETURN PERIOD AND RISK OF HYDROLOGIC EVENTS. II: APPLICATIONS

Abstract

A mathematical formulation to estimate return periods and risks of failure of complex hydrologic events such as those arising from dependent floods and droughts have been examined in the first part of this paper. Specifically, some relationships and algorithms for computing return periods and associated risks for runs arising from independent and dependent events assuming that dependence is represented by a two-state Markov chain have been proposed. The applicability of these procedures is illustrated herein, considering several types of hydrological events with emphasis on those where dependence is important. First, meteorological droughts based on annual precipitation are considered as examples of events consisting of runs in independent trials. Then, minimum streamflows and maximum annual lake outflows are included as examples of dependent events, assuming that dependence is represented by a simple Markov chain. Also, hydrological droughts based on annual streamflow series are considered. In addition, the estimation of return period and risk are illustrated by data generation.