Changes in base flow indices and flow duration curves of rivers originated from Sabalan Mountain under the influence of climatic variables

Rainfall and discharge components are important parameters among climatic and hydrological parameters that identifying their behavior for water resources management is of particular importance. The aim of this study was to analyze the changes in river flow indicators in quantifying Basal Flow Index (BFI) and Flow Duration Curve (FDC) in the Sabalan mountain rivers. Therefore, first, the daily flow discharge in river gauge stations were divided into two periods pre and post the change based on changes in flow indicators or climatic components. Then, general statistics, BFI and FDC were calculated using River Analysis Package (RAP) software. The results showed that the maximum statistical values of river flow in Lay, Nir and Pol-e-Soltani stations have significantly decreased. BFI in most stations had an increasing trend, which can be related to the possible continuation of snowmelt in the foothills of Sabalan. In Ahl-e-Iman, Lay, Nir, Pol-e-Soltani and Viladaraq stations in the periods pre- and post-change, flow discharge in 50% of the days of the year was equal to or more than 0.081 and 0.108, 0.1 and 0.125, 1.3 and 0.884, 0.71 and 0.372, 0.07 and 0.055 cms were estimated. In general, the change in river flow indicators has been affected by the occurrence of significant changes in rainfall and temperature components