## 5 Conclusions  
Large amounts of sediment deposition are one of the main causes of the lake water environment destruction, and permeable dams have been shown to be an effective way of controlling sediment and purifying water. This paper proposes a cascade permeable dam with two sets of dam materials of different particle sizes, and the variation in hydraulic parameters, turbidity, and sediment interception efficiency under different sediment concentrations and discharges are obtained by physical experiments, and the following conclusions are drawn:  
1. Cascade permeable dams can effectively reduce the amount of sediment entering the lake. When D = 1-2 mm, the percentage of intercepted sediment mass in the Dam zone ranged from 75% to 89%, which was significantly greater than that in the Stagnant zone (\(\leq\)3%) and Deposition zone (9-21%). When D = 3-5 mm, the percentage of intercepted sediment mass in the Dam zone ranged from 53% to 70%, which was also greater than that in the Stagnant zone (\(\leq\)3%) and Deposition zone (29-45%), indicating that the Dam zone has a better sediment interception performance.
2. The cascade permeable dam with a small particle size has larger water level differences and weaker discharge capacity. The sediment interception rate (\(\eta\)) of the cascade permeable dam with a small particle size is much higher than that with a large particle size, and is positively correlated with the sediment concentration. As the upstream dam reduces the sediment supply to the subsequent dams, the \(\eta\) of the dams in the same group of experiments is \(\eta_{1}>\eta_{2}>\eta_{3}>\eta_{4}\), indicating that 1# dam has the best sediment interception efficiency.
3. As the pores of the dam bodies are continuously blocked by sediment particles, the permeability coefficient (\(k\)) of the dam body gradually decreases with time. The smaller the particle size of the dam material, the smaller the permeability coefficient of the dam body. The permeability coefficient of the dam body with large and small particle sizes shows a variation of \(\Delta k_{1}>\Delta k_{2}>\Delta k_{3}\) overall, indicating that the discharge capacity of the cascade permeable dam gradually decreases.
4. Both the turbidity removal rate and the intercepted sediment mass in the cascade permeable dam are positively correlated with the number of dams. For 4# dam, the lower the water level in front of the dam, the smaller the effective volume of the dam body, and the less optimistic sediment interception efficiency. The percentage of the sediment interception mass of the cascade permeable dam is only 3.6-7.7%. Therefore, in the actual engineering application, the number of dam bodies of the cascade permeable dam should be reasonably designed.  
In this study, only the effect of the sediment concentration and discharge were considered. In fact, the spacing, thickness, and number of the dams in a cascade permeable dam can also affect the sediment deposition rate and infiltration pattern. The effect of dam thickness and spacing on the sediment interception efficiency of cascade permeable dams should be further explored.  
Conceptualization, J.L. and H.Z.; methodology, J.L., H.Z. and L.P.; validation, J.C.; formal analysis, J.L.; investigation, N.L. and M.W.; resources, H.Z.; data curation, J.C.; writing--original draft preparation, J.L.; writing--review and editing, H.Z. and L.P.; visualization, J.L.; supervision, H.Z.; software, J.L.; project administration, H.Z.; funding acquisition, H.Z. All authors have read and agreed to the published version of the manuscript.  
This work was supported by Key R&D Program of Sichuan Provincial Science and Technology Department (2022 YFG0016).  
Not applicable.  
The data in figures and tables used to support the findings of this study are included herein.  
We thank [PERSON] of Xihua University and [PERSON] of Sichuan Water Conservancy College for providing us with helpful discussion and instruction on topics related to this work.  
The authors declare no conflict of interest.