Late Quaternary landscape evolution in a small catchment on the Chinese Loess Plateau

Late Quaternary landscape evolution was analysed with reference to a small (0.08 km2) drainage basin system in southeastern Gansu Province, southwestern Chinese Loess Plateau. In this region, V-shaped valleys with broad valley floors are prominent landscape features whose basic shape already existed prior to MIS 2. During MIS 2 the valley bottoms were infilled with fluvially reworked loess, today forming accumulation terraces. Infrared optically stimulated luminescence (IRSL) dating of these loess-like deposits assigned them to the time span ranging from 22.5 to 17.7 ka BP. During the late Holocene, valley fills were partly eroded, and the receiving stream channel was deepened by at least 25 m close to the confluence of the study site's channels. These alternating erosion and accumulation phases were triggered by climatic factors or human impact. In the most recent past, the high landscape sensitivity of the Chinese Loess Plateau has led to increasing soil conservation measures that have effectively confined surface erosion. However, the lack of drainage on the artificial terraces induces piping processes.