Climatological parameters fluctuations in the watershed of Haft-Barm Wetland complex and their ecological water requirement

Haft- Barm wetland complex has been the only permanent freshwater wetland in Fars province from a dacede ago. Considering the ecological and tourism importance of this complex, the goals of this research were to study the long-term changes of climatological factors in wetland watershed and to estimate its ecological water requirement. For this purpose, the changes of precipitation, temperature, evaporation as well as drought condition were investigated during the last three decades. Also, the volume of runoff in the watershed was calculated by Justin's method. In order to estimate the ecological water requirement of the wetland, the surface changes of wetland and the permanent and temporary water bodies of wetland during the past three decades were investigated using satellite images. Finally, by exploring the relationship between the abundance of migratory birds as well as the selected species with changes in water surface areas of wetlands, the ecological water requirement of wetland was determined.  The results showed a significant decrease in rainfall and an increase in temperature and severity of drought during last decade in comparison to long condition. Also, a 40% decrease in runoff and significant decrease in lakes volume were observed in recent years compared to the long-term average. The ecological water requirement was estimated as 1.500, 2.100 and 2.800 Mcm for drought, normal and wet seasons, respectively. Considering the high degredation rate in the area, it is necessary to seriously protect the surface and underground water resources in the wetland and its watershed in order to guarantee the ecological water flow requirement of wetland.