## 6 Conclusions  
To assess the safety of EDFs in the stilling basin after technical reconstruction at the downstream side of the sluice, corresponding HPO tests were conducted to investigate the operational behavior and hydrodynamic characteristics during flood discharge in the open channel. Based on these tests, the following conclusions were drawn:1. HPO tests provide a more accurate and reliable assessment of the effectiveness of reconstructed EDFs in open channels at hydropower stations;
2. The results of HPO tests can be used to improve the design and operation of EDFs by providing detailed information on the characteristics of discharge flow and the dynamic response of hydraulic structures during sluice opening periods;
3. Several suggestions are provided for improving the flood discharge mode at hydropower stations based on the results of the HPO tests to ensure safe operation of open channels during flood discharge;
4. The importance of studying HPO tests on reconstructed EDFs is highlighted to ensure their safe and efficient operation in open channels at hydropower stations and to advance our understanding of complex hydraulic phenomena.  
This article offers insights into the effectiveness of reconstructed energy dissipation facilities in open channels at hydropower stations through HPO tests. However, there remains considerable scope for further research in this domain. Future investigations could concentrate on enhancing the HPO test methodology and devising more sophisticated techniques for measuring and analyzing flow patterns, free water surface fluctuations, air entrainment in air-water flows, and pulsating pressure changes in open channels under various flood discharge conditions. A thorough examination of scale effects between HPO and HMT is also warranted. The ultimate objective is to explore the complex characteristics of two-phase air-water fluid dynamics and substantial energy dissipation rates, ensuring the safe and efficient operation of open channels at hydropower stations while advancing our knowledge in this field.  
[PERSON], [PERSON], [PERSON], [PERSON], [PERSON] and [PERSON] designed the analysis, developed the software, wrote the original and revised manuscript, and conducted data analysis and details of the work. [PERSON] and [PERSON] conceptualized and designed the research experiment, wrote the original/revised drafts, designed, re-designed, and verified image data analysis, and guided the direction of the work. All authors have read and agreed to the published version of the manuscript.  
This research was financially supported by the Yunnan Natural Science Foundation of China (Grant No. KKZ3202004052), Anhui International Joint Research Center of Data Diagnosis and Smart Maintenance on Bridge Structures (Grant No. 2021 AHGHZD02), and the Open Foundation for Key Laboratory of Yunnan University (Grant No. KKZ6202104005).  
Not applicable.  
The data presented in this study are available on request from the corresponding author.  
The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.