عنوان مقاله [English]
Monitoring systems and definition of mitigation actions are two of the main components of every drought management plan. Appropriate link between these two can help the timely and effective implementation of a management program. So, in this study it is attempted to design a probabilistic system as based on the risk to manage the Zarrineh-rood basin. Within this approach, drought alert thresholds are defined in probabilistic terms and based on reservoir storage volume. Short term simulations are carried out using the software package WEAP and four scenarios (normal, pre-alert, alert and emergency) associated with different levels of severity of drought defined. Then threshold values and coefficients of decreasing demand are identified, considering the probability of existence of a certain deficit of demand in a certain time horizon using Genetic Algorithm Optimization Model. These coefficients for crop production, horticulture, and environmental needs were estimated as follows: The coefficients at pre-alert level are equal to 31.30%, 7.30% and 47.8%, at the alert level equal to 33.60%, 9.2% and 50.60% and at the emergency level they amount to 35.5%, 11.10% and 52.20%, respectively. Considering the fact that the coefficients of decreasing demand had a significant impact on the reduction of the indicators of deficit, especially during the crisis period of 1999 to 2001, this resulted in the prevention of the complete emptying of the reservoir during the mentioned period.