Estimation of ecological water flow requirements of Bakhtegan and Tashk internationally important wetlands and contribution of climatic and anthropogenic factors in their drought

Bakhtegan and Tashk internationally important Wetland is one of the largest wetland sites in Iran that has dried up in recent years. This study was conducted to estimate the ecological water requirements of this wetland site. For this purpose, first the basic data including long term trend of rainfall, SPI and flow rates of Kor and Sivand rivers as the main feeding sources of wetlands were analysed. Then, to estimate the ecological water requirement, changes in the wetland area in the long run were investigated. Also, changes in Flamingo species as an ecologic index were studied in line with wetlands surface changes. The results showed that the amount of ecological water required to maintain the ecological functions of Bakhtegan and Tashk wetland from the Kor-Sivand River at the entrance of the wetland in dry, normal and wet yearsare 700, 826 and 1037 million cubic meters, respectively. The best times to release the water from upstream sources are February, March and April, respectively. The most important factors contributing in the drought of wetlands include   increase of agrilands to fed excessive increase of the basin population, non-sustainable management of water resources, construction of new dams in watershed, significant reduction of rainfall and increasing of dry seasons during last two decades.