## 1 Introduction  
With the rapid development of the global economy and the gradual growth of the demand for mineral resources, mining activities are becoming more and more frequent [1, 2, 3]. Tailings refer to the \"waste residue\" discharged after the valuable concentrate is selected by the concentrator during the mining process. These tailings are produced in large quantities and contain favorable and harmful components that cannot be treated temporarily. The indiscriminate discharge will cause resource loss, farmland coverage, river siltation, and environmental pollution [4, 5]. In order to prevent pollution, a tailings pond must be built to store the tailings. Tailing reservoirs are dangerous sources of man-made debris flow with high potential energy, which has the risk of dam break. The influence of hydraulic forces, sedimentation, and geological activities may further destabilize the structure of the tailing reservoir, leading to serious accidents and posing a significant long-term environmental and safety threat [6, 7, 8, 9]. In recent years, tailings dam accidents have occurred in many countries around the world, resulting in a large number of casualties and environmental disasters [10]. In 2015, Brazil's Mariana Dam collapsed, killing 19 people, injuring hundreds more, and releasing toxic heavy metals into downstream rivers, causing untold damage to local water supplies and ecosystems [11]. In 2019, a massive collapse of the Brumadinho Dam killed 259 people and heavily polluted the nearby Paraopeba River [12]. In 2020, a leak at the Luming Mining tailings pond in China polluted parts of the river, farmland, and forest land. Strengthening the safety monitoring and management of tailings ponds and discovering potential safety hazards in time can effectively prevent the occurrence of tailings dam failure accidents and reduce the risk of casualties and environmental damage. The monitoring content of the tailings reservoir mainly includes the dam stability, seepage, reservoir water level, and dry beach monitoring. The tailings and water are mixed into a slurry in the concentrator and discharged into the tailing reservoir for storage through drainage pipes. With the gradual discharge of the tailing slurry, the water in the tailings slurry gradually settles and gathers, while the solid tailings form a sedimentation body on the intercepting surface of the tailings dam. The tailings dry beach refers to the sedimentation surface extending from the tailings dam to the waterline (Figure 1a). The dry beach length and slope ratio are important indicators for assessing the safe operation of tailings ponds [13]. The traditional monitoring methods of the tailings pond dry beach include laser measurement and slope estimation methods. The laser measurement method (Figure 1b) uses a laser rangefinder and an angle meter to measure the distance L and the angle \(\alpha\) of the beam. Multiple groups of \(\alpha\) and L can be obtained by performing repeated scanning measurements on the dry beach of the tailings pond. The slope of the dry beach can be measured based on the geometric relationship, and the length of the dry beach can be measured by combining the elevation difference between the top of the beach and the water surface. The laser measurement method is vulnerable to the limitation of the laser range, especially in complex terrains or long distances, where it may not fully cover the entire dry beach area. The slope estimation method (Figure 1c) uses two radar level gauges along a dry beach profile: one at the top near the dam and the other toward the water level. The slope is calculated from the elevation difference and horizontal distance between the level gauges. The dry beach length is then determined by combining the slope with the height difference between the beach top and the water surface. The disadvantage of this method is that it requires frequent calibration of the instrument to prevent flooding of the  
Figure 1: Schematic diagram of tailings pond and dry beach monitoring.