Mid-infrared spectroscopy tracing of sediment sources in highly erosive catchments on the Chinese Loess Plateau

Abstract

<p>Identification of the sediment sources is the key to control soil erosion in the Chinese Loess Plateau (CLP), which is helpful to understand the process of erosion, transport and deposition, and is of great significance to formulate soil conservation measures according to the local conditions. The current research attempted to use the mid-infrared (MIR) spectroscopy fingerprinting method to trace sediment sources within nine small catchments in the hilly-gully region of the CLP. Two major categories of sediment sources were identified: gully and topsoil. Sediments trapped by check dams were collected as the final sediment transferred by soil erosion. The two types of sediment sources could be discriminated by MIR spectroscopy. The partial least squares regression (PLSR) analyses was applied to quantify the contributions of gully and topsoil to the total final sediment. The MIR-PLSR results showed that gully contributed 19% to 66% of the total sediment with an average of 33 ± 16% in the nine small catchments. A comparison between the MIR spectroscopy method and the geochemical fingerprinting method in one catchment revealed that although the two methods agreed well on the gully contributions, the two methods produced a significant difference (R<sup>2</sup>=0.4). The analyses further suggested that although gully accounted for relative large proportions of final sediment, topsoil erosion was the predominant process in small dam controlled catchments on the CLP.</p>