Geravand, Fatemeh ， Hossein-Panahi, Bahareh ， Hosseini, Seiyed Mossa
2025-10-02 JOURNAL OF APPLIED WATER ENGINEERING AND RESEARCH 2025 13(卷), 4(期), (383-392页)
This study investigates streamflow components (baseflow and surface flow) during the recession period using the classical hydrograph recession technique and a two-component mixing model (salinograph and hydrograph). The methodologies were applied to the Mahabad and Zarrinehroud Rivers in northwestern Iran, using data on streamflow and salinity in 2016. Results indicated that baseflow indices from the mixing model (0.945 for Mahabad, 0.978 for Zarrinehroud) were higher than those from the hydrograph recession method (0.811 and 0.960, respectively), suggesting greater accuracy in capturing groundwater influence. While the classical hydrograph recession method yielded a constant groundwater recession coefficient (alpha g) of 0.006 d-1, the mixing model estimated a variable alpha g range of 0.004 to 0.010 d-1. Incorporating salinity into hydrograph analysis improved baseflow separation and captured the interaction between flow and water quality, enhancing estimates of groundwater contributions. These findings support improved hydrological modeling in semi-arid regions and underscore groundwater's role in sustaining streamflow.