Document Type : Research Paper
Department of Natural Resources and Environmental Engineering, School of Agriculture, Shiraz University, Shiraz 71441-65186, Iran
Fars Department of Environment, Shiraz, Iran.
Bakhtegan and Tashk internationally important Wetlands 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 these wetlands. To this end, 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 wetlands 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 wetlands from the Kor-Sivand River at the entrance of the wetland in minimum, optimal and maximum conditions are 700, 826 and 1037 million cubic meters, respectively. The best time to release the water from upstream sources is February, March and April, respectively. The most important factors contributing in the drying up of wetlands include the excessive increase of the basin population and the increase of agrilands and non-sustainable management of water resources, construction of new dams in watershed and significant reduction of rainfall and increasing of drying seasons during last two decades.