Sediment provenance in the Shudu Lake basin, northwest Yunnan Province, China, as revealed by composite fingerprinting

Abstract

Composite fingerprinting represents an effective method of reconstructing sediment-source changes in remote areas where long-term hydrological and sediment accretion records do not exist. A ca. 50-year record of sediment deposition was determined for a small catchment at Shudu, situated in northwest Yunnan Province, China. Woodland, pasture, shrubland and channel bank material are identified as the most likely sediment sources and this was confirmed using a composite sediment fingerprinting approach. Based on the findings of the fingerprinting technique, variations in the geochemical signature associated with lacustrine sediment deposits indicate that 49.2 % of the total catchment sediment yield over an approximate 50-year period originated from channel banks. In contrast, 19.2 % originated from pasture, 18.6 % originated from shrubland, and 13 % from woodland. The relative contributions of eroded sediment from both woodland and shrubland have generally remained stable over the period investigated, whereas the contribution of material from pasture has increased over recent decades. This is tentatively attributed to increased grazing pressure, which is probably due to increased stocking densities which have gradually exceeded the carrying capacity and regenerative capabilities of the available grassland.