Combined effect of rain temperature and antecedent soil moisture on runoff and erosion on Loess

- Loess soil erosion was examined with raindrops temperature of 2, 20 and 35 °C.
- For dry soil, a slight decrease in runoff and erosion was found between 20 and 35 °C.
- For wet soil, runoff yield increased by 27% between 2 and 20 °C.
- For wet soil, sediment yield was three times greater in 20 °C than in 2 °C.
- For cold rain, sediment yield was 5.2 times greater in wet soil than dry one.

The effect of antecedent soil moisture content on runoff and soil erosion was investigated in many previous studies. These studies revealed contradictory findings. The present study investigated the combined effect of raindrop temperatures and antecedent soil moisture on interrill flow generation and erosion of a loamy soil (Loess), using a rotating disk rain simulator. The experiments were applied to soil with two pre-prepared moisture conditions: hygroscopic and field capacity. For each condition, three rainfall temperatures were applied: 2 (cold), 20 (mid-temperature), and 35 °C (hot).The effect of antecedent soil moisture on soil erosion found to be depended on rainfall temperature. For the cold rainfall, the sediment yield of the dry soil was 5.2 times greater than that of the pre-wetted soil, whereas for the mid-temperature and for the hot rainfall it was 1.5 and 1.2, respectively. For the pre-wetted soil, the sediment yield in the mid-temperature rainfall was 3 times greater than in the cold one. In the light of the predicted changes in global climate characteristics, an increase in rainfall temperature might lead to enhanced soil loss in Loess.