Background The Xingjiaba Hydropower Station is situated in the arid and semi-arid valley region of the lower Jinsha River, which is characterized by rugged terrain and a high concentration of rainfall. These conditions contribute to increased soil erosion and degradation. This study aims to investigate the impact of slope ecological restoration on soil aggregate stability and to uncover the primary mechanisms behind soil aggregate destabilization in arid valley regions, thereby providing a deeper understanding of the processes involved.

Methods Soils on 6 slopes with vegetated concrete (CBS), frame lattice beam mulching (FB), guest soil spraying (SS), thick layer substrate spraying (TBS), natural forest (NF), and disposal site (AS) of Xiangjiaba Hydropower Station were subjected to three treatments of pre-wetting and post-disturbance (WS), fast wetting (FW), and slow wetting (SW) by using the dry sieving method and the Le Bissonnais (LB) method, and the distribution of agglomerates, average weight, diameter, geometric mean diameter, and erodibility K characteristics were comparatively analyzed for the soils of each slope under different treatments.

Results 1) After dry sieving, the percentage of aggregates with a particle size > 0.25 mm was > 90.00% for CBS, SS and AS, higher than 85.00% for TBS and FB, and lower than 75.78% for NF. The percentage of large aggregates was higher for CBS, SS and AS after the LB method, with the percentages of aggregates with a particle size of 2.00 mm under the three treatments being 55.53%, 60.96% and 56.15%, respectively. 55.53%, 60.96% and 56.15% > 2.00 mm particle size, respectively; the proportions of aggregates in TBS and FB were 40.03% and 46.24%, respectively, while NF was only 75.24%. The percentage of aggregates in TBS and FB was 40.03% and 46.24%, respectively; NF was only 75.24% and 46.24%; and NF was the smallest, only 36.84%. 2) Under the LB method, the MWD values except AS were SW > WS > FW, and the MSW values were distributed in the range of 2.16 – 3.26 mm. the MFW values were distributed in the range of 1.56–2.71 mm. the MWS values were distributed in the range of 2.10 – 3.03 mm. the GMD behaved similarly to the MWD. GMD behaved similarly to MWD values, with values ranging from 1.15 – 2.38, 1.10 – 2.07, and 0.73 – 1.85, respectively. 3) The K values under the three treatments ranged from 0.0190 – 0.0330, 0.0220 – 0.0480, and 0.0200 – 0.0333, with the overall performance of FW > WS > SW, and the K values of the NF under the three treatments being the largest. RSI (28.11 – 2.25) exhibited all were much larger than RMI (10.92 – 0.40).

Conclusions The dissipation effect of bubble bursting in the soil pores produced by heavy rain or torrential rainfall has the greatest damage to the ecological restoration of the soil aggregates on the side slopes; due to the special topography of the site and the rainfall conditions, the LB method is not completely applicable to this site, and the experimental results should be considered in conjunction with the field conditions.