Dr. Kendall et Ja. Dracup, ON THE GENERATION OF DROUGHT EVENTS USING AN ALTERNATING RENEWAL-REWARD MODEL, Stochastic hydrology and hydraulics, 6(1), 1992, pp. 55-68
This research study focused on the hypothesis that extreme drought and
high streamflow events come from different independent populations wi
th different probability distributions which need to be studied separa
tely, rather than considering the streamflow population as a whole. Th
e inability of traditional streamflow generator models to consistently
reproduce the frequency of occurrence of severe droughts observed in
the historical record has been questioned by many researchers. Our stu
dy focused on the development of a stochastic event generator model wh
ich would be capable of doing so. This was accomplished in a two-step
process by first generating the drought event, and then deriving the s
treamflows which comprised that event. The model considered for this a
nalysis was an alternating renewal-reward procedure that cycles betwee
n event on and off times, and is representative of drought or high str
eamflow event duration. The reward gained while the event is on or off
represents drought severity or high streamflow surplus. Geometric and
gamma distributions were considered for drought duration and deficit
respectively. Model validation was performed using calculated required
capacities from the sequent peak algorithm.