Determining Erosion Types Contributions to the Sediment Yield Using Sediment Fingerprinting Method (Case study: Margan watershed, Makoo)

Because of many problems associated with traditional procedures for identifying sediment sources, fingerprinting techniques, based on physical, chemical and organic properties of sediment and source materials, are increasingly being used as a valuable and effective alternative approach to assembling such information. In this method, a suitable composite (set) of diagnostic properties and a multivariate mixing model are employed to estimate the relative contribution of sediment sources to the sediments transported to basin outlet. In this study, using suitable composites of geochemical elements, radionuclides, organic carbon, nitrogen and phosphorous, capable of discriminating surface and subsurface erosions of the study basin, and a multivariate mixing model were used to determine contributions of those erosion types to the sediment yield. The suitable composite fingerprints (elements) were obtained using discriminant analysis. The study basin is Margan watershed of Pouldasht, located in Makoo township, West Azarbaijan province. The suitable composite fingerprints having capability to distinguish the above mentioned erosion types include OC, Cr, 137Cs and P. Mean contributions from the two main erosion types, namely surface erosions (sheet and rill erosions) and subsurface erosions (gully, channel and river bank erosions) were estimated as 30.65% and 69.35% respectively. Low mean absolute errors (less than 13%) show high degree of agreement between measured and predicted properties. High model efficiencies (greater than 0.99) confirm the goodness of fit of the mixing models. Also it is argued that fingerprinting estimates for sediment sources are consistent with field observations. Although a number of limitations must be recognized, the fingerprinting approach to source ascription has high efficiency to determine relative importance of sediment sources (surface and subsurface erosions) in the study basin.