Comparison of base flow separation techniques and its seasonal variations in some watersheds of Ardabil Province

Base flow is an important component of flow hydrograph which originated from groundwater flow reserves. The aim of this study was to compare graphically and recursive digital filtering techniques in base flow separation and selection of appropriate methods to estimate the base flow contribution in number of rivers over Ardebil Province. Also, temporal changes of base flow and surface runoff through months of the year were analyzed in a 22-year period from 1389 to 1368 over 22 watersheds in the Ardabil Province is another aim of this study. Therefore, the performance graphical methods, and digital filtering techniques, were evaluated in base flow separation. The comparison of separated base flow amounts with recession analysis method indicates that the One-parameter algorithm was the best method in separation of base flow, was used to estimate the base flow contribution through the studied stations. Then the average values of total runoff and base flow were calculated in different seasonal changes of base flow were prepared.The low amount of base flow were observed in the Eastern part of the study area, while the West and Southwest parts of the Ardabil Provinces had the highest base flow component, as well as the maximum amount of the base flow is related to the three months of the spring season. It should be noted that the highest base flow amount were observed in summer season in the Hir, Sola, and Iril stations, the potential variations in the surface runoff and base flow components through seasons in different watersheds.