Determining Geological Formation Contribution in Suspended Sediment Yield Using Sediment Fingerprinting Technique (Ziarat Drainage Basin, Golestan Province)

Sediment tracing method has been proven as a successful and effective method to determining sediment sources contribution in sediment yield in recent two decades. Ziarat drainage basin in Golestan province is one of the water supply resources in Gorgan city. The main lithological formations in the study area are Gorgan Schists, Quaternary alluvial deposits, Shemshak and Khosh yeylagh Formation which could have an important role in erosion and sediment yield. For tracing sediment, 14 samples of suspended sediment from catchment outlet during precipitation events and 43 representative samples of geologic formations (as sediment sources) from the soil surface (depth of 0-5 cm) were collected and geochemical elements, 137Cs and organic carbon were measured in the samples as tracers. The optimum set of tracers was selected by using Kruskal-Wallis test and discriminate function analysis. The results of this study indicate that the tracers including OC, 137Cs and Cu have the most potential to discriminate the sediment sources. The result of the sediment fingerprinting mixing model showed that Shemshak formation, fluvial deposition, Khosh yeylagh and Shist formation have 42, 31/9 and 23/7, 1.6% of the sediment contributions in sediment yield, respectively.