Use of caesium-137 measurements to investigate erosion and sediment sources within a small drainage basin in the loess plateau of China

The contributions of sediment from different geomorpholigical units within a small basin in the Loess Plateau have been determined using caesium‐137 as a tracer. The mean caesium‐137 content of sediment originating from the hill area, where sheet and rill erosion are predominant, was 3–37 Bq kg‐1, whereas no caesium‐137 was detected in the sediment originating from the gully area where gullying and gravitational erosion are predominant. The mean caesium‐137 content of sediment from two flood deposits was 0–23 Bq kg‐1 and 0–89 Bq kg‐1. The relative contribution from the hill area in the two floods was 7 per cent and 26 per cent, whilst that from the gully area was 93 per cent and 74 per cent.