In order to study the influence of engineering disturbance on the soil anti-erodibility and anti-scourability of loess

taking Beishan

Chengguan District

Lanzhou City as the study area

the undisturbed soils were sampled from four plots: 1-year filled plot (T1a)

5-year filled plot (T5a)

7-year dug plot (W7a) and natural grassland plot (C). In the laboratory

the dry-wet sieve method was used to determine the soil aggregate related indicators to study the soil anti-erodibility

and the anti-scour trough was used to study the soil anti-scourability

and the factors affecting the soil anti-erodibility and anti-scourability were analyzed. The results showed that the mean weight diameter of soil water-stable aggregates (MWDw) and the proportion of aggregates>0.25 mm (w(δ>0.25)w) of the surface layer (0—10 cm) of each sample surface showed C>W7a>T5a>T1a. The soil percentage of aggregates destruction (PAD) showed T1a>T5a>W7a>C. The average of soil water stable aggregates fractal dimension (Dw) in the surface layer of dug and filled plots was 2.82

the Dw of C plot was 2.74. The anti-erodibility of the surface layer soil of the C was significantly stronger than those of the dug and filled sites. The MWDw and w(δ>0.25)w of the middle and lower soil (10—20 cm and 20—30 cm) of the T5a and W7a plots were significantly lower than those of the surface layer soil. The surface soil anti-erosion coefficients of each sample showed W7a>C>T5a>T1a

and the values of W7a and C sample plots were relatively close. Soil electrical conductivity

organic matter and root system were the main factors affecting soil anti-erodibility and soil anti-scourability. In addition

soil biological crusts could also affect soil anti-scourability. These factors are closely related to the shelving years of dug and filled plots. This means

these factors gradually change as the shelving time of dug and filled plots increases

which is beneficial to the increase of MWDw and w(δ>0.25)w

and the decrease of PAD of disturbed soil

and the scouring intensity of surface soil is close to that of natural grassland. Engineering disturbance would significantly reduce the soil anti-erodibility and soil anti-scourability of loess

and necessary water and soil conservation measures should be taken to reduce the risk of soil erosion.