Assessment of climate change impacts on river hydrology and habitat suitability of 'Oxynoemacheilus bergianus'. Case study: Kordan River, Iran

Iran is located in a geographical location that is not immune from climate change effects. Therefore, it is necessary to assess the influence of climate change on water resources since this part of the ecosystem is the first component that will be affected by climate change. The main purpose of this study is to assess climate change impacts on environmental flows by using hydrological indicators in Kordan River, Iran. In this regard, at first, the future climate change in the region was projected by using HadCM3 general circulation model in three 30-year periods, 2011-2040, 2041-2070, and 2071-2099, considering the A2 and B1 emission scenarios. Afterwards, Kordan River streamflow was simulated by using the SWAT model for the baseline period (1985-2010) and the future and hydrological indicators, such as magnitude, duration, timing, and frequency of extreme flows, were analyzed. Results showed a reduction in discharge. Under the A2 scenario, discharge decreased from 3.31 to 2.66 m³/s, while under the B1 scenario, this reduction was up to 2.86 m³/s for 100 years into the future. In addition to reduction of discharge, the occurrence time of maximum and minimum flows is projected to change as well. This phenomenon will change the habitat suitability and introduce some risks for aquatic life. Finally, in order to analyze Kordan River habitat suitability, we chose 'Oxynoemacheilus bergianus', which can be a suitable index for the ecosystem. In this regard, Habitat Suitability Index (HSI) was used, which is obtained based on river characteristics such as water depth, velocity, and water temperature. According to the results, the percentage of time that HSI is at a rate between 0.4 and 0.6 is expected to decrease from 100-70% to 80-60% under both scenarios by 2071-2099.