Quantifying provenance of reservoir sediment using multiple composite fingerprints in an arid region experiencing both wind and water erosion

Abstract

Quantitative information on sediment sources is useful for developing targeted protection measures that effectively control soil erosion in a watershed. In this study, a multiple composite fingerprints method was tested and used for quantifying the sediment provenance of the Danghe River, and for providing effective sediment control strategies for the watershed in an arid region experiencing both wind and water erosion. Surface samples were taken from three geomorphic source areas of dunes, gobi, and upstream mountains; and sediment samples from the watercourses near the reservoir. To accommodate the wide range of sediment size distributions resulting from the fluvial and aeolian processes, sediment contributions from each source were estimated for each of six particle size groups. The results showed that the proportional contributions from each source to the reservoir sediments were 56.73% from upstream mountains, 26.36% from gobi, and 16.91% from dunes, with the relative contributions in each size group following a similar trend. The largest fraction of the sediment was from the 0.063–0.1 mm particle size group, accounting for about 37.09% of the total, in which 4%, 7.59%, and 25.50% were from dunes, gobi, and upstream mountains. Our results also indicated that selective erosion existed in both erosion processes, especially in wind erosion process, and multiple particle size tracking should be used in the cases of severe selective erosion to improve the accuracy of estimation. Also, the sediment contribution rate per unit area was the largest from dunes; thus, controlling wind-blown sand to the river by stabilizing the dunes is recommended to reduce the reservoir siltation.