Modeling system for canyon river and alluvial fan interaction

Abstract

The application relates to a simulation experiment system of canyon river and alluvial fan interaction, which comprises a groundwater reservoir, a water inlet pool, a water and sand mixing narrow slot, a sediment deposition pool and a water outlet pool. The simulation experiment system can meet the research needs of river and alluvial fan interaction, can inversely analyze the process of alluvial fan development forming an alluvial plain, and has the advantages of simple operation, precise control, convenient measurement, low cost and the like.

Description

Technical Field

[0001] This invention relates to the field of river dynamics technology, and in particular to a simulation experimental system for the interaction between canyon rivers and alluvial fans. Background Technology

[0002] After flowing water enters a relatively open canyon area from a mountainous region, the sediment it carries is deposited, forming fan-shaped alluvial fans. The siltation and development of alluvial fans simultaneously shapes river morphology, and rivers, in turn, profoundly influence the development of alluvial fans. Under this interaction, the silt deposits continuously grow, eventually developing into river valley alluvial plains under the constraint of the mountains on both sides of the canyon. With continuous socio-economic development, human activities in river valley plains have increased significantly, and the connection between regional geomorphological evolution and human production and life has become closer. More frequent human alteration of the landforms disrupts the normal evolutionary process of alluvial fans, increasing the probability of natural disasters. Therefore, studying the development process of alluvial fans into plains and analyzing the interaction between rivers and alluvial fans not only helps to understand the geomorphological evolution process and patterns in plain areas but also provides guidance for the rational utilization of river and lake shoreline sandbars and the prevention and control of flood disaster risks.

[0003] Physical model experiments are an effective means of studying geomorphic evolution and water-sediment interaction. Due to their advantages such as high timeliness, intuitive results, ease of operation, and convenient measurement, they have been widely used in the field of geomorphology in recent years. Domestic and international scholars have conducted numerous physical model experiments to study the formation mechanism and development patterns of alluvial fans. However, most of these studies focus solely on the sedimentary structure within the alluvial fan, emphasizing the continuous deposition of sediment in the model experiments, with the results applied to geology and oil and gas resource exploration; or they focus solely on the evolution of river morphology, emphasizing the development of river types under certain flow conditions, with the results applied to river dynamics and river flood control engineering. Few model experiments combine sediment deposition with river evolution to analyze the interaction between rivers and alluvial fans, and to study the symbiotic development process of alluvial fans gradually developing into alluvial plains. Summary of the Invention

[0004] To address the above problems, this invention provides a simulation experimental system for the interaction between canyon rivers and alluvial fans, which can meet the research needs of river-alluvial fan interaction and invert the process of alluvial fan development to form alluvial plains.

[0005] The technical solution adopted in this invention is: a simulation experimental system for the interaction between canyon rivers and alluvial fans, characterized in that: it includes an underground reservoir, an inlet pool, a water-sediment mixing trough, a sedimentation pool, and an outlet pool. The underground reservoir is installed below the base plate of the experimental system, and a water pump is installed at the bottom. The water pump is connected to the inlet pool through a water supply pipe. The downstream section of the inlet pool gradually narrows and connects to the water-sediment mixing trough. The water-sediment mixing trough is long and narrow, and a sand feeder is installed on top. The sedimentation pool is located downstream of the water-sediment mixing trough and is planar. The structure is rectangular in shape, simulating the narrow and elongated landform of a natural canyon, and emphasizing the influence of lateral constraints on the development of alluvial fans. Above the sedimentation pond, there is a topographic surveying instrument for measuring the cross-sectional topography of the alluvial fan and a camera for recording the evolution of river landforms during the experiment. A tailrace weir is located at the downstream end of the sedimentation pond, and the outlet pond is located downstream of the tailrace weir. The outlet pond is equipped with a sand-blocking grid, an outlet control gate, and a return water pipe. Downstream of the sand-blocking grid, an outlet control gate is installed, and downstream of the outlet control gate, a return water pipe is connected to an underground reservoir.

[0006] Preferably, a regulating pool is provided in the narrow section downstream of the inlet pool, and the upstream side and left and right side walls of the regulating pool are overflow weirs, with the weir crest height lower than the side wall height of the inlet pool and the narrow water-sand mixing channel.

[0007] Preferably, the top of the sidewall of the water-sand mixing narrow channel is provided with a longitudinal slide rail, a transverse slide rail is mounted on the longitudinal slide rail, and a topographic surveying instrument for measuring the cross-sectional topography of the alluvial fan is installed on the transverse slide rail.

[0008] Preferably, the topographic surveying instrument is connected to a computer via a connecting cable and can move autonomously along a transverse slide rail according to computer instructions to measure the topography of the alluvial fan cross section; the camera is connected to the computer via a wireless signal.

[0009] Preferably, a camera bracket is erected above the sedimentation pond, and a camera is mounted on the top of the camera bracket for capturing and recording the evolution of the river landform during the experiment.

[0010] Preferably, the underground reservoir is 3m long, 4m wide, and 3m deep.

[0011] Preferably, the water supply pipe outlet is fixed to the bottom of the front wall of the water inlet pool, and the water supply pipe is equipped with an inlet control valve and a flow meter.

[0012] Preferably, the narrow water-sand mixing trough is 1m long, 0.13m wide, and 0.3m high.

[0013] Preferably, the sedimentation pond is 18m long and 2.7m wide, with a solid foundation at the bottom and a bottom slope of 0.001.

[0014] Preferably, the sand adding rate of the sand adder is adjusted by the sand adder controller.

[0015] The beneficial effects achieved by this invention are: the simulation experimental system of this invention can not only meet the research needs of the interaction between rivers and alluvial fans and invert the process of alluvial fan development to form alluvial plains, but also has the advantages of simple operation, precise control, convenient measurement and low cost.

[0016] The present invention has the following advantages:

[0017] 1. It can simulate the interaction between water and sediment in the process of alluvial fan developing into alluvial plain, and can simultaneously observe the sediment deposition of alluvial fan and the periodic evolution of rivers. The experimental system has a simple structure, convenient operation, low cost, and significant experimental results, making it suitable for widespread use.

[0018] 2. By adding a regulating tank at the tail end of the inlet pool, the upstream flow was effectively stabilized, solving the problem of difficult flow control in the narrow water-sand mixing channel during the initial and final stages of the experiment. Since the entire sediment deposition process is lengthy and needs to be divided into several sub-experiments, the addition of the regulating tank ensures that the water flow and sediment conditions are essentially the same as in the previous sub-experiment at the start of each sub-experiment, thus maintaining consistent experimental conditions and environment throughout the entire experiment.

[0019] 3. It effectively fills the gap in previous experiments on the interaction between alluvial fan sediment deposition and river periodic evolution, improves the limitations of previous experiments that focused solely on river evolution or sediment deposition, and successfully simulates the formation process of alluvial plains, providing an effective research method for exploring the origin of canyon-type alluvial plains and the origin of rivers in the plains.

[0020] 4. The sedimentation pond is designed with a relatively long and narrow rectangle shape, rather than the square or fan shape commonly used in previous experiments. This experimental environment is closer to the natural narrow canyon landform, which can effectively simulate the constraint effect of the canyon mountains on the deposition of alluvial fans and the evolution of rivers. The experimental system does not focus on the initial formation stage of alluvial fans, but rather on the development and transformation process of alluvial fans into canyon-type alluvial plains under the constraint of the mountains on both sides.

[0021] 5. By selecting experimental sediments with different particle size distributions and specific gravities, adjusting different sediment addition rates, setting different water flow rates, or combining the above-mentioned different experimental water and sediment conditions, the effects of different influencing factors such as sediment, water flow, and sediment content on the interaction between rivers and alluvial fans can be systematically studied. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the overall structure of the simulation experiment system of the present invention;

[0023] Figure 2 for Figure 1 Top view;

[0024] Figure 3 This is a schematic diagram of the cross-section;

[0025] Figure 4 These are experimental photos taken during the early stages of alluvial fan development (the two edges of the alluvial fan have not yet contacted the lateral walls);

[0026] Figure 5 These are experimental photos taken during the later stages of alluvial fan development (the two edges of the alluvial fan have already contacted the lateral walls);

[0027] Figure 6 This describes the evolution of the longitudinal profile of the alluvial fan over time.

[0028] Figure 7 This describes the evolution of the cross-sectional topography of the alluvial fan over time.

[0029] Figure 8 This refers to the interaction between alluvial fans and rivers during their development.

[0030] In the diagram: 1. Underground reservoir; 2. Water pump; 3. Water supply pipe; 4. Inlet control valve; 5. Flow meter; 6. Inlet pool; 7. Regulating pool; 8. Sand feeder; 9. Water-sand mixing trough; 10. Sedimentation pool; 11. Tailwater weir; 12. Outlet pool; 13. Sand barrier; 14. Outlet control gate; 15. Tailwall of the flume; 16. Return pipe; 17. Topographic surveying instrument; 18. Camera; 19. Inlet pool guide wall; 20. Regulating pool overflow weir; 21. Sand feeder controller; 2. Sidewall; 23. Lateral slide rail; 24. Camera bracket; 25. Flume bottom plate; 26. Sidewall longitudinal slide rail; 27. Computer; 28. Mobile water supply hose; A. Sedimentation body. Detailed Implementation

[0031] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] like Figure 1-3As shown, the present invention provides a simulation experimental system for the interaction between canyon rivers and alluvial fans, comprising an underground reservoir 1, an inlet pool 6, a water-sediment mixing trough 9, a sedimentation pool 10, and an outlet pool 12. The underground reservoir 1 is installed below the base plate of the experimental system, and a water pump 2 is installed at the bottom. The water pump 2 is connected to the inlet pool 6 through a water supply pipe 3. The downstream section of the inlet pool 6 gradually narrows and connects to the water-sediment mixing trough 9. The water-sediment mixing trough 9 is elongated and narrow, with a sand feeder 8 installed on top. The sedimentation pool 10 is located downstream of the water-sediment mixing trough 9 and has a rectangular planar shape, simulating a natural canyon. The narrow and elongated landform strengthens the influence of the lateral constraints of the sidewall 22 on the development of the alluvial fan; a topographic surveying instrument 17 for measuring the cross-sectional topography of the alluvial fan and a camera 18 for recording the evolution of the river landform during the experiment are installed above the sedimentation pond 10; a tailrace weir 11 is provided at the downstream end of the sedimentation pond 10, and the outlet pond 12 is located downstream of the tailrace weir 11. The outlet pond 12 is equipped with a sand-blocking grid 13, an outlet control gate 14 and a return water pipe 16; an outlet control gate 14 is installed downstream of the sand-blocking grid 13, and a return water pipe 16 is provided downstream of the outlet control gate 14 to connect with the underground reservoir 1.

[0033] In this embodiment, a regulating pool 7 is provided in the narrow section downstream of the inlet pool 6. The upstream side and the left and right side walls of the regulating pool 7 are overflow weirs, and the height of the weir crest is lower than the height of the side walls of the inlet pool 6 and the water-sand mixing narrow channel 9.

[0034] The inlet pool 6, regulating pool 7, water-sand mixing narrow channel 9, and sedimentation pool 10 are all located on the same foundation surface, which has a certain slope to facilitate the downstream movement of water carrying sediment. The underground reservoir 1, outlet pool 12, and return water pipe 10 are all located below the aforementioned foundation surface.

[0035] To ensure the effectiveness of the experiment on the interaction between the river and the alluvial fan and to reduce the adverse effects of an excessively large scale, the experimental setup is relatively large, and the weight of the water and sediment is also substantial. To ensure the structural strength of the experimental system, the side walls, bottom plate, and underground structure are made of reinforced concrete, while the longitudinal sliding rails 26 on the side walls and the outlet control gate 14 are made of steel.

[0036] The regulating pool 7 is located at the tail end of the inlet pool 6. Its area is significantly smaller than that of the inlet pool 6. The top elevation of the overflow weir of the regulating pool 7 is slightly lower than the height of the side wall of the inlet pool 6. This can stabilize the water flow, reduce the impact of water flow fluctuations in the inlet pool 6 on the water and sediment environment in the sedimentation pool 10, and help control the water flow conditions when the experiment starts and stops, preventing the experiment from being affected by the excessively long lag time of water level changes in the inlet pool 6.

[0037] The sand feeder 8 is installed above the narrow water-sand mixing trough 9. The sand and gravel in the sand feeder 8 can be manually sieved to control the particle size distribution and specific gravity. The sand feeding rate of the sand feeder 8 can be adjusted. After the sand and gravel fall into the narrow water-sand mixing trough 9 below at a certain rate, they are fully mixed with the water flowing through the narrow water-sand mixing trough 9 to form a sand-laden water flow that enters the downstream sediment deposition pond 10. Different sand feeding rates, different sediment types, and different water flow rates can create different experimental water-sand conditions.

[0038] Camera 18 is connected to computer 27 via wireless signal. Multiple cameras 18 can be controlled by computer 27 to take pictures synchronously. The complete image of the water tank experiment can be obtained by stitching together the pictures taken by multiple cameras 18. When measuring the water flow velocity during the experiment, tracer particles need to be released at the inlet of sedimentation tank 10. At the same time, the camera 18 is used to take pictures continuously. The water flow velocity is calculated by the time interval of the pictures and the distance of the tracer particles moving measured in the pictures. The camera bracket 24 is a movable aluminum alloy structure, and the number and installation position of the cameras 18 can be determined according to different experimental needs.

[0039] The topographic surveying instrument 17 is connected to the computer 27 via a connecting cable. Mounted on the transverse slide rail 23, the instrument can automatically move along it to measure the cross-sectional topographic data of the sedimentary body and transmit and save it to the computer 27. The transverse slide rail 23 can move freely along the longitudinal slide rail 26 along the side wall. The transverse slide rail 23 and the longitudinal slide rail 26 should maintain a perpendicular relationship. Each time the transverse slide rail 23 moves to a new position, the topographic surveying instrument 17 can measure a new cross-sectional topography. After integrating and processing the cross-sectional topography data from multiple measurements, a three-dimensional topography of the sedimentary body A can be generated. When measuring the topography, the topographic surveying instrument 17 needs to ensure that there is a certain depth of water above the sedimentary body A. Therefore, the experiment must be stopped, the outlet control gate 14 closed, and water added to the sedimentary sedimentation tank 10 until the sedimentary body A is submerged. To prevent damage to the topography of the sedimentary body A during the water addition process, a mobile water addition hose 28 is used to add water to the outlet tank 12.

[0040] A sand-blocking grid 13 is installed in the outlet pool 12 to intercept the silt entering the outlet pool and prevent fine silt from returning to the underground reservoir 1 with the return water pipe 16 and clogging the water pump 2. Experimenters need to clean the sand and gravel in front of the sand-blocking grid 13 regularly to prevent the water from flowing out of the outlet pool 12 from being obstructed.

[0041] This invention discloses a simulation experimental system for the interaction between a canyon river and an alluvial fan, comprising an underground reservoir 1, an inlet pool 6, a water-sediment mixing trough 9, a sedimentation pool 10, and an outlet pool 12. The underground reservoir 1 is 3m long, 4m wide, and 3m deep, installed below the base plate of the experimental system. The reservoir stores water and supplies water to the entire experimental system. A water pump 2 is installed at the bottom, connected to the inlet pool 6 via a water supply pipe 3. The water supply pipe 3 is a steel structure, with its outlet fixed to the bottom of the front wall of the inlet pool 6. An inlet control valve 4 and a flow meter 5 are installed on the water supply pipe 3. The inlet pool 6 is 3m long and 2.7m wide, gradually narrowing downstream before connecting to the water-sediment mixing trough 9. The downstream section of the inlet pool 6... The narrow section is equipped with a regulating pool 7. The upstream side and left and right sidewalls of the regulating pool 7 are overflow weirs, with the weir crest height lower than the sidewall heights of the inlet pool 6 and the water-sediment mixing trough 9. The water-sediment mixing trough 9 is 1m long, 0.13m wide, and 0.3m high, with a long and narrow shape to facilitate thorough mixing of water and sediment. A sand feeder 8 is installed above the water-sediment mixing trough 9, and the sand feeder rate is adjusted by a sand feeder controller 21. The sediment deposition pool 10 is the main area of ​​interaction between the river and the alluvial fan, 18m long and 2.7m wide, with a solid foundation and a bottom slope of 0.001. The sediment deposition pool 10 has a rectangular plan shape to simulate the narrow and elongated landform of a natural canyon, strengthening the sidewalls. Factors influencing the development of alluvial fans: A longitudinal sliding rail 26, made of steel, is laid on the top of the sidewall 22 of the sedimentation pond. A transverse sliding rail 23 is mounted on the longitudinal sliding rail 26. A topographic surveying instrument 17 is installed on the transverse sliding rail 23, connected to a computer via a connecting cable. The instrument can move autonomously along the transverse sliding rail 23 according to computer instructions to measure the cross-sectional topography of the alluvial fan. A camera bracket 24, made of movable aluminum alloy, is mounted above the sedimentation pond 10. The number and installation position of cameras can be determined according to different experimental needs. A camera 18 is installed on the top of the bracket to record the evolution of river landforms during the experiment. The camera 18 is connected to the computer via a wireless signal. The number of camera brackets 24 and cameras 18 can be set according to experimental requirements; a tailrace weir 11 is provided at the downstream end of the sedimentation pond 10 to control the water depth of the sedimentation pond 10 during the experiment, simulating the alluvial fan deposition environment under natural conditions; the effluent pond 12 is located downstream of the tailrace weir 11; the effluent pond 12 is equipped with a sand-blocking grid 13, an effluent control gate 14, and a return water pipe 16; the sand-blocking grid 13 is used to intercept excess sediment from the sedimentation pond 10, preventing sediment from returning to the underground reservoir 1 with the return water pipe 16 and clogging the water pump 2; the effluent control gate 14 is installed downstream of the sand-blocking grid 13 to control the outlet water level and flow rate of the experimental system; the return water pipe 16 is connected to the underground reservoir 1 downstream of the effluent control gate 14.

[0042] The process and operation steps of conducting simulation experiments using the simulation experiment system of this invention are as follows:

[0043] according to Figures 1-3 The experimental system structure shown is configured with all instruments and components connected. The outlet control gate 14 is opened, the sand mixer controller 21 is set to the designated position, and the water pump 2 is started. Water flows from the underground reservoir 1 into the inlet pool 6. The inlet control valve 4 is adjusted so that the flow meter 5 reading reaches the experimental set value. The water level in the inlet pool 6 gradually rises. When the water level exceeds the overflow weir height of the regulating pool 7, the water flows into the regulating pool 7 and the water-sand mixing narrow channel 9. At this time, the sand mixer 8 is started, and the sediment in the sand mixer 8 falls into the water-sand mixing narrow channel 9, mixing thoroughly with the water to form a sediment-laden flow. The sediment-laden flow simulates the interaction between a canyon river and an alluvial fan in the sediment deposition pool 10. During this process, most of the sediment settles in the sediment deposition pool 10, while a small portion flows with the water into the outlet pool 12 and is intercepted by the sand barrier 13. After entering the outlet pool 12, the water flows back to the underground reservoir 1 via the return pipe 16, and is then pumped back into the inlet pool by the water pump 2.

[0044] During the experiment, multiple cameras 18 were controlled by computer 27 to take pictures synchronously at regular or irregular intervals to record the experimental phenomena. The pictures taken by multiple cameras were then stitched together to obtain a complete image of the water tank experiment. When measuring the water flow velocity during the experiment, tracer particles were artificially released into the narrow water-sand mixing tank 9, and the camera 18 was used to take continuous pictures at the same time. The water flow velocity was then calculated by the time interval between the pictures and the distance the tracer particles moved measured in the pictures.

[0045] When measuring the topography of the sedimentary body, the experiment needs to be stopped. The specific operating steps are as follows: turn off water pump 2, and then, when no water flows into the regulating tank 7, turn off the sand feeder 8. Close the outlet control gate 14, and inject water into the outlet tank 12 through the movable water injection hose 28. When the water depth above the sedimentary body in the sedimentary tank 10 reaches 10cm, stop injecting water. At this time, move the topographic measuring instrument 17 together with the transverse slide rail 23 to the upstream edge of the sedimentary tank. According to the experimental requirements, measure the cross-sectional topography of the sedimentary body at certain intervals (10cm-50cm recommended) downstream, and finally integrate all the cross-sectional topography to form a three-dimensional topography of the sedimentary body. The topographic measurement of each cross-section is automatically completed by the computer-controlled topographic measuring instrument. Throughout the measurement process, the transverse slide rail 23 should be kept perpendicular to the longitudinal slide rail 26 on the side wall. The process of moving the transverse slide rail 23 along the longitudinal slide rail 26 on the side wall can be manually completed by the experimenter.

[0046] The timing for topographic measurements should be chosen when representative landforms appear at different stages of the sedimentary body, such as the elongated lobe stage, the fan-shaped sedimentary body stage, the moment when a clear river morphology appears, or the moment when the alluvial fan contacts the two sidewalls, etc. After each topographic measurement, the experiment should be restarted at an appropriate time based on the sedimentary body formed in the previous experiment, until the predetermined experimental objective is achieved, thus formally completing a complete simulation experiment of the interaction between canyon river and alluvial fan. Before restarting the experiment, the topographic measuring instrument 17 and the transverse slide rail 23 should be reset, the water outlet control gate 14 should be opened to drain the water in the sedimentary sedimentation pool 10, and then the water pump 2 should be restarted, repeating the previous operating procedure.

[0047] During the experiment, it was observed that as time progressed, sediment gradually accumulated, alluvial fans gradually developed, and river morphology exhibited periodic changes. In the early stages of the experiment, the alluvial fan area was small and not yet affected by the lateral walls; its planar shape was symmetrical, elliptical or fan-shaped, and the river morphology on its surface was mostly radial or dendritic (e.g., Figure 4 As shown in the diagram, over time, the alluvial fan area increases, and sediment gradually fills the canyon space between the two side walls. The alluvial fan is laterally constrained, and the river morphology on its surface becomes more complex and more concentrated under the constraint of the side walls, causing the alluvial fan to develop forward more rapidly (as shown in the diagram). Figure 5 As shown in the figure, during the development of alluvial fans, their cross-sectional and longitudinal profiles gradually rise and advance, exhibiting similar overall morphology, but the longitudinal slope tends to gradually slow down (e.g., Figure 6 and Figure 7 As the alluvial fan gradually develops, the river morphology on its surface exhibits periodic changes, revealing the interaction mechanism between the alluvial fan and the river: Just before the alluvial fan surface is about to break through and straighten the river channel, the water flow is scattered and in a thin layer; when the sediment accumulation at the downstream end of the river channel reaches a certain extent, it begins to affect the downstream flow of the upstream water; after the alluvial fan reaches a certain scale, it gradually emerges from the water surface, and the water flow is gradually divided into several distributaries; as the alluvial fan continues to expand, the two separated distributaries, due to their large angle of divergence, ram against the sidewalls; as the divergence point continues to move upward and the angle of divergence continues to increase, the ramming position of the distributary and the sidewalls moves upstream, causing their convergence point near the axis to gradually move upstream as well; when a large amount of sediment backfills and fills most of the river section, the upstream water level is finally significantly raised due to backfilling, and the water flow overflows the natural dikes on both banks, restoring the scattered sheet-like flow morphology on the flat sand surface, thus completing one evolutionary cycle (as shown in the image). Figure 8 (As shown).

[0048] It should be noted that the above description of the technical solutions is exemplary, and this specification may be embodied in different forms and should not be construed as limiting it to the technical solutions set forth herein. Rather, providing these descriptions will ensure that the disclosure of this invention is thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Furthermore, the technical solutions of this invention are defined only by the scope of the claims.

[0049] Finally, it should be noted that the above embodiments are merely representative examples of the present invention. Obviously, the present invention is not limited to the above embodiments and many variations are possible. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention should be considered within the protection scope of the present invention.

Claims

1. A simulation experimental system for the interaction between canyon rivers and alluvial fans, characterized in that: The system includes an underground reservoir, an intake pool, a narrow water-sediment mixing channel, a sedimentation pool, and an outlet pool. The underground reservoir is installed below the base plate of the experimental system, with a water pump at its bottom. The water pump is connected to the intake pool via a water supply pipe. The downstream section of the intake pool gradually narrows and connects to the narrow water-sediment mixing channel. The narrow water-sediment mixing channel is elongated and narrow, with a sand feeder installed above it. The sedimentation pool is located downstream of the narrow water-sediment mixing channel and has a rectangular planar shape, simulating the elongated landform of a natural canyon to enhance the influence of lateral constraints on alluvial fan development. Above the sedimentation pool, there is a topographic surveying instrument for measuring the cross-sectional topography of the alluvial fan and a camera for recording the evolution of river landforms during the experiment. A tailrace weir is located at the downstream end of the sedimentation pool, and the outlet pool is located downstream of the tailrace weir. The outlet pool contains a sand-trapping grid, an outlet control gate, and a return water pipe. The outlet control gate is installed downstream of the sand-trapping grid, and a return water pipe is connected to the underground reservoir downstream of the outlet control gate. A regulating pool is provided in the narrow section downstream of the inlet pool. The upstream side and the left and right side walls of the regulating pool are overflow weirs, and the height of the weir crest is lower than the height of the side walls of the inlet pool and the narrow water-sand mixing channel. The top of the sidewall of the sedimentation pond is covered with a longitudinal sliding rail, and a transverse sliding rail is mounted on the longitudinal sliding rail. A topographic measuring instrument for measuring the cross-sectional topography of the alluvial fan is installed on the transverse sliding rail. The transverse sliding rail can move freely along the longitudinal sliding rail of the sidewall and remains perpendicular to the longitudinal sliding rail of the sidewall. Each time the transverse sliding rail moves to a new position, the topographic measuring instrument measures a new cross-sectional topography. After integrating and processing the cross-sectional topography of multiple measurements, a three-dimensional topography of sedimentary body A is generated. When the topographic measuring instrument is measuring the topography, it is necessary to ensure that there is a certain depth of water above sedimentary body A. Therefore, the experiment needs to be stopped, the water outlet control gate closed, and water added to the sedimentation pond until sedimentary body A is submerged. A camera bracket is erected above the sedimentation tank, and a camera is installed on the top of the camera bracket to record the evolution of the river landform during the experiment. When measuring the water flow velocity during the experiment, tracer particles need to be released at the inlet of the sedimentation tank, and the camera is used to take continuous pictures. The water flow velocity is estimated by the time interval between the pictures and the distance the tracer particles move in the pictures.

2. The simulation experimental system for the interaction between canyon rivers and alluvial fans according to claim 1, characterized in that: The topographic surveying instrument is connected to the computer via a connecting cable and can move along the transverse slide rail according to computer instructions to measure the topography of the alluvial fan cross section; the camera is connected to the computer via a wireless signal.

3. The simulation experimental system for the interaction between canyon rivers and alluvial fans according to claim 1, characterized in that: The underground reservoir is 3m long, 4m wide, and 3m deep.

4. The simulation experimental system for the interaction between canyon rivers and alluvial fans according to claim 1, characterized in that: The water supply pipe outlet is fixed to the bottom of the front wall of the water inlet pool, and the water supply pipe is equipped with an inlet control valve and a flow meter.

5. The simulation experimental system for the interaction between canyon rivers and alluvial fans according to claim 1, characterized in that: The narrow water-sand mixing channel is 1m long, 0.13m wide, and 0.3m high.

6. The simulation experimental system for the interaction between canyon rivers and alluvial fans according to claim 1, characterized in that: The sedimentation pond is 18m long and 2.7m wide, with a solid foundation at the bottom and a bottom slope of 0.

001.

7. The simulation experimental system for the interaction between canyon rivers and alluvial fans according to claim 1, characterized in that: The sand adding rate of the sand adder is adjusted by the sand adder controller.

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