Determining the Contributions of River Flow Hydrograph Components in some River Gauge Stations of Ardabil Province

Separation of flow hydrograph components can be used to analysis of base flow, flood runoff amount and contribution of groundwater flow in sustaining river flow regime. Flow recession analysis method is acceptable and widely used in separation of river hydrograph and extraction of the master recession curve in the separation of hydrograph components allows for the estimation of the contribution of different flow components. The simple method of separating hydrograph components based on the analysis of the recession curve of the flow time series can be used to determine the ratio of each component of the flow hydrograph. This study aimed to determine the contribution of surface, sub-surface and base flow and assessing their temporal changes in some river stations of Ardabil province. Thus, the daily discharge data and HydroOffice software packages were used through RC and FlowComp programs to recession curve analysis and hydrograph separation, respectively. According to the results, the average values of surface, sub-surface and base flow components over the studied stations were 20.41, 29.45, and 50.14 percent, respectively. The results showed that the highest percentage of base flow component is determined in Viladaragh station (79%) and lowest base flow amount was observed in Kozetopraghi station (34%). The highest and lowest percentage of subsurface runoff component were calculated for Nanekran and Arbabkandi with 40% and 10%, respectively. The maximum amount of surface runoff component is related to Kozetopraghi (33%) and Hir (6%) stations. Identifying a dominant increase or decrease pattern in flow components is not possible according to the results of temporal changes in the contribution of hydrograph components. Also, the highest amount and contribution of flow hydrograph is related to base flow, sub-surface flow, and surface runoff components.