Based on hyperchaos and discrete fractional Fourier transform (DFRFT) algorithm, a digital image watermarking algorithm based on hyperchaos sequence and the discrete fractional Fourier is presented in this paper. First, the original image and the watermarking image are transformed, respectively. At the same time, according to cipher sequence generated by the hyperchaotic array, the watermarking image's real part and imaginary part are encrypted, respectively. Second, the encryption watermark image's real part and imaginary part alternative embedded into the host FRFT coefficients. Then, the watermarking image is obtained after Fourier inversely transformed. Moreover, different attacks such as noise, JPEG compression and the cropping have been analyzed for the robustness of the watermark image. The results of the experiment have shown that the proposed algorithm is robust against common image manipulations.

Channel erosion and sediment entrainment amplify rainstorm-triggered debris flows, but their interaction with topographic constraints remains poorly quantified. To reveal the controlling mechanism of erosion amplification on the disaster-forming process of rainstorm-type debris flows, using the 2016 Zhangba Xiaosha River event in Yunnan, China, we reconstructed debris-flow motion, erosion, and deposition with RAMMS::DEBRISFLOW. Five bed-erosion scenarios (0, 0.25, 0.50, 0.75 and 1.0 m) were used to assess changes in deposit thickness, runout, velocity, impact pressure, and volume amplification. The 1.0 m baseline scenario successfully reproduced the observed path, depositional extent, and representative deposit thickness. Increasing the equivalent erosion depth from 0 to 1.0 m increased the total debris-flow volume from 2.0 × 10⁴ to 4.27 × 10⁴ m³, yielding an amplification factor of 2.14; without erosion, maximum runout was 44.2% shorter. Along-channel erosion supply increases the mass, flow depth and momentum of the moving mass, forming an amplification chain of “sediment supply−scale amplification−momentum maintenance−frontal propagation”. Feedback may exist between actual erosion intensity, flow velocity and flow depth, but the equivalent erosion depth in RAMMS scenarios in this study is a predefined parameter. Topography exerted reach-specific controls: steep upstream channels promoted initiation and acceleration, the middle reach dominated erosional bulking, and the wider, gentler downstream reach enhanced dissipation and deposition. Within the erosion scenarios of 0.75–1.0 m set in this study, when the equivalent erosion depth increased further, the newly entrained sediment mainly increased deposit thickness and inundation extent, while the increment of maximum runout distance was limited. The event disaster scale resulted from coupled erosion-induced amplification and longitudinal topographic constraints. Hazard assessments should integrate initial initiation volume, erodible channel sediment, and local reach-scale topography.

Deep excavation reduces lateral confinement and can increase tangential stress, promoting brittle failure in highly stressed rock. However, the effects of bolt number and spacing on mechanical response and damage evolution under this stress path remain insufficiently understood. In this study, parallel RFPA^3D simulations were conducted for true-triaxial single-face unloading followed by continued axial loading, assuming perfect bonding at the bolt–rock interface. Two parameter series examined bolt numbers from zero to four (M0–M4) and bolt spacings from 10 to 80 mm. Stress–strain response, acoustic emission activity, failure morphology, damage area ratio (A_d), and box-counting fractal dimension (D_f) were analysed. Bolt reinforcement increased post-unloading peak stress and restricted the inward extent of damage, while damage persisted near the unloaded face and within the inter-bolt regions. Peak stress increased from approximately 345 MPa in M0 to 363 MPa in M3, then decreased slightly to 358 MPa in M4, showing that reinforcement gains were not proportional to bolt number. Bolt spacing had a modest effect on peak stress but a clearer influence on damage continuity and inward extent. Among the tested spacings, the 40 mm case (D40) achieved the highest peak stress of 370.0 MPa and the lowest A_d of 23.85%, with a low D_f of 1.431. In contrast, the 80 mm case (D80) exhibited more extensive and spatially complex damage (A_d = 30.78%, D_f = 1.677). A_d and D_f provided complementary descriptions of damage extent and spatial complexity. These numerical results provide a quantitative basis for comparing reinforcement configurations under the investigated specimen-scale conditions.

The Yizhong River Basin, located in an alpine gorge on the southeastern Tibetan Plateau, experiences recurrent landslide-derived debris flows originating from moraine-covered source areas. This study integrates unmanned aerial vehicle (UAV)-based geomorphic interpretation, field geological profiling, laboratory direct shear tests, rainfall analysis, and sequential SEEP/W–FLAC3D modeling to examine source-area preconditioning and rainfall-related slope response. Present-day UAV-derived profiles and field observations support a two-layer configuration in which unconsolidated moraine deposits overlie fractured bedrock and are consistent with an inferred sequence of headward incision, gully deepening, and lateral expansion; this sequence is interpreted conceptually rather than as a chronologically resolved reconstruction. The moraine cover represents a substantial high-elevation sediment source, with an approximate potential volume on the order of 3.9 × 10⁵ m³. Laboratory wetting from the natural state (6.3% water content) to a controlled wet state (16.8%) reduced cohesion from 24.5 to 15.3 kPa and the internal friction angle from 30.2° to 26.4°. Under an idealized 8 h equal-total rainfall scenario, the sequential seepage–stability model yielded a factor-of-safety decrease from 1.33 to 0.92 and a maximum downward displacement of 22.3 cm, with deformation concentrated near the mapped collapse–slide zone. The recurrent activity is therefore interpreted as a feedback pathway linking moraine-slope instability, gully erosion, sediment recharge, and renewed failure. The results provide a case-based assessment of how moraine–bedrock preconditioning and rainfall-related weakening may jointly contribute to recurrent source-area instability, highlighting the combined roles of geological structure, sediment supply, and hydrological weakening in debris-flow initiation and recurrence.