Accurately predicting ski-jump flood discharge atomization is crucial for designing effective disaster-mitigation measures, particularly because low ambient pressure increases the risk of atomized protection in high-altitude regions. However, owing to the complex effects of low ambient pressure on strongly coupled atomized field sources, it is difficult to fully describe the comprehensive behaviour of such sources theoretically, which limits the further development of random splashing numerical models. In this paper, a refined random splashing numerical model characterized by low ambient pressure is developed based on experimental results and applied to high-altitude earth–rockfill dam projects. Compared with the reference ambient pressure condition ( P ₀ = 101.457 kPa), which corresponds to the same flood discharge flow, a decrease in ambient pressure by 0.1P ₀ leads to a maximum change rate not exceeding 10 m for the characteristic boundary of the 10 mm/h atomized rain intensity line at the QX Hydropower Station. This observation also applies to both the 40 mm/h and 10 mm/h atomized rain intensity lines at the RM Hydropower Station. For the two groups of flip bucket types designed for the RM Hydropower station, the loads associated with atomized protection are predominantly concentrated on the left bank. The maximum height of the 10 mm/h atomized rain intensity line affected by atomized rain ranges from 0.83 to 0.85 times the maximum dam height of 315 m. The distance between the farthest downstream boundary and the Spillway No. 3 outlet is between 666.80 and 692.40 metres. Since the flip bucket shape variations only slightly affect the atomization zone extent, further optimization is needed. The study can provide valuable methodological and decision-making support for safeguarding against existing and potential impacts within areas affected by flood discharge atomization from high-altitude hydropower stations.

A better understanding of the atomized rain characteristics in low ambient pressure areas is beneficial in reducing the jeopardizing effect of flood discharge atomization on high-altitude hydropower stations. A random splash experiment is designed with two measurement planes to investigate the effects of low ambient pressure on downstream atomized rain under the complicated conditions of low ambient pressure (within 0.60P₀~1.00P₀) and high waterjet velocity (at a magnitude of 10 m/s). The results demonstrate that the atomized rain (rain intensity ≥ 2 mm/h) downstream, characterized by two-dimensional distribution, can be enhanced by decreasing the ambient pressure and by increasing the inflow discharge. When the ambient pressure decreases at the same inflow discharge, both the distance of the rain intensity lines (40 mm/h, 10 mm/h, 2 mm/h) in the horizontal plane from the constricted nozzle outlet and the average rain amount in the inclined plane within the atomized source ratio of ((0~30) × 10⁻³)% appear as “linear” growth. With the ambient pressure decreasing by 0.10P₀, the range of those characteristic rain intensity lines is expanded by 0.68%~1.37%, and the average rain amount is enlarged by 11.06%~20.48%. When keeping the low ambient pressure unchanged, both the point average rain intensity reduction along the releasing centerline and the surface average rain amount growth with increased inflow discharge all follow an exponential function. The aeration reduction in the waterjet boundary and the resistance reduction in atomized water-droplets are contributing factors for the enhancement effect of low ambient pressure. This study can enable the establishment of a foundation to further predict flood discharge atomization in a high-altitude environment.

The construction and operation of high dam projects at high altitudes have led to concerns about the effectiveness of flood discharge security predictions resulting from the greater flood discharge atomized rain caused by ambient pressure reduction. In this study, self-similar characteristics and variation in atomized raindrop size distributions are analyzed to understand the phenomenon of increased atomized rain intensity under low ambient pressure from a mesoscopic scale. The monographic experiments are characterized by a low ambient pressure range (0.66P₀–1.02P₀) and a high waterjet velocity range (13.89–15.74 m/s). When the ambient pressure decreases by 0.10P₀ (P₀ = 101.325 kPa) from the reference atmospheric pressure condition as the other conditions remain fixed, the total number concentration in a two-dimensional atomized raindrop spectrum (number/(54 cm²)) and the peak value of the individual three-dimensional number concentration (number/(m³·mm) increase, which can lead to the required industry standard protective level of atomized zones increasing by one level in some cases. In addition, the spectrum trend and typical particle size ranges of the atomized raindrop size distributions present self-similarity as the ambient pressure decreases. The above studies further confirm the effects of low-ambient pressure enhancement on flood discharge atomized rain intensity, which can provide a theoretical basis for the development of random splash simulation models characterized by low pressure for high-altitude hydropower stations.

The creation of innovative learning environments in courses to provide sustained talent support has long remained a central research concern for high-quality social development. Neglected foundational skills in professional course clusters are often a hidden barrier to higher education for sustainable development (HESD). To close five persistent foundational skill gaps across improper citation (J1), ineffective figure use (J2), poor analysis (J3), irresponsible AI use (J4), and comprehensive application (J5) within the hydraulic engineering course cluster, a four-stage deliberate practice module (5Di-40Pr-5Tr-3Cm) has been embedded into a two-week hydraulic model experiment course, and its learning outcomes are systematically evaluated. A systematic analysis of its achievement levels across neglected foundational skill indicators of J1~J5 at each stage was conducted, stratified by the overall cohort and subgroups (P: objective demand, T: behavior type, G: optimization methods). The key findings include: ① deliberate practice demonstrates better teaching outcomes than lecture-based instruction, which can be evidenced in 2026, when J5’s achievement levels at the 3Cm stage yielded a moderate effect size relative to the 2025 lecture-based condition (d = 0.42); compared with the 2024 no-intervention baseline, the cumulative effect is a obvious increasing trend (d = 1.43); ② In far-transfer subgroup diagnosis, P2 (medium objective demand) shows a rank-order reversal, low at 40Pr but higher at 3Cm, and is identified as the “partial understanding” group and providing a diagnostic anchor for tiered intervention; ③ In near-transfer pathway diagnosis, J5’s low performance in 5Tr (65.35%, below overall mean of 83.09%; CV = 7%) stems from two distinct pathways: a “knowledge-deficit pathway” (max-decay subgroups) and a “processing-load pathway” (subgroups where J1, J2 do not exhibit max decay). In addition, stage-specific thresholds (40Pr: 90%, range 60~99%; 5Tr and 3Cm: 83% ± 3%, range of for 40Pr, mean = 90%, recommended range = 60~99%; for 5Tr, mean = 83% ± 3%, range = 65~96% and 75~90%) provide quantitative benchmarks for targeted intervention. These cumulative findings are intended to advance the evaluation paradigm of engineering practice courses from “total score attainment” toward “structural diagnosis” and align with the competency-oriented philosophy of higher education for sustainable development (HESD).