Assessing sediment yield and sources using fingerprinting method in a representative catchment of the Loess Plateau, China

摘要

Quantitative assessment of sediment yield and sources is of great importance for future soil and water conservation and watershed management in erosion-prone areas. This study investigated sediment yield and sources by using a simple fingerprinting method in a dam-controlled watershed on the northern Loess Plateau. The sampling sediment profile exhibited 24 flood couplets corresponding to rainfall storms from 2001 to 2014. A total of 2.05 x 10(5) t sediment was trapped during the period. The annual sediment yield varied from 0 to 430 t ha(-1) year(-1), with an average annual sediment yield of 146.1 t ha(-1) year(-1). Ten sediment properties (i.e., sigma C-13, sigma N-15, TOC, TN, C/N, X-lf, X-hf, X-fd, Cs-137, Pb-210) were potentially selected to identify the sediment sources. The multivariate discriminant function analysis (DFA) test suggested that three soil properties (X-hf, TN, and Cs-137) comprised the optimum composite fingerprinting. The results demonstrated that sandstone contributed nearly 90% of sediment in 2012 and 56.1% in 2003. The contribution from arable land varied from 5.2% in 2005 to 44.6% within the period of 2013-2014. On average, approximately 74.06% of sediment originated from the weathered sandstone, followed by 15.67% from arable land, and the remaining 10.27% from uncultivated land. Our finding indicated that bare sandstone was the main sediment source, leading to relatively high sediment yield in the study area. This study provides a method with great potential for sediment yields assessment and sediment source identification in ungauged watersheds on the Loess Plateau.