## 1 Introduction  
Braided rivers are one of the important types of river systems [1], and their deposits serve as high-quality reservoirs for oil, gas, and groundwater, with significant exploration potential. The evolution of such a river system in time and space is primarily controlled by base-level variations, tectonism, and the climate [2, 3, 4]. At the same time, it is also affected by strong erosion during seasonal floods, local sediment supply, and bar form migration [5; 6]. These factors determine the complexity and variability of the sedimentary system and further limit the extensive application of its depositional models, so predicting and reconstructing the braided river alluvial architectural structure is a challenge [7; 8]. One of the major limiting factors for the construction of its alluvial architecture is the paucity of real geological datasets from field observations [9; 10], such as good field outcrop and hydrological and topographic data. In recent years, with the widespread application of technology such as aerial surveys using drone flights [11; 12; 13], three-dimensional (3D) photogrammetric modeling [14], and ground-penetrating radar (GPR) [15] and the deepening of geological research, a large amount of real field data has been obtained, which greatly promotes the quantitative characterization of braided river reservoir scales and tends to provide semi-quantified to quantified reservoir descriptions [16; 17]. Previous studies on the alluvial architectural structure of braided rivers focused on the planimetric characteristics and morphodynamic processes of modern ones [18; 19; 20; 21; 22] and concentrated on detailed sedimentological analysis based on either two-dimensional (2D) or pseudo-three-dimensional (3D) outcrops [23; 24; 25; 26]. However, regarding the description and characterization of modern ones, with the exception of work on the level of bars in the Calamus River [19; 20] and the Jamuna River [21], few studies have examined the formation mechanism, evolution process, nature of accretion, and bedforms to conduct a systematic analysis of the whole braided river alluvial structure. For the present analysis of braided river architectural structure in the field outcrop area, either the 6-order (0 th-5 th) surfaces that bound architectural elements [27; 28] or the \"lithofacies-lithofacies combination\" analysis method [3; 26] is applied to understanding the sandstone geometry and the connection between architectural elements and key surfaces without involving the sedimentary process, scale, and time background [29]. These methods easily oversimplify important details that are difficult to characterize clearly enough in complex braided river architectural structures. For example, downstream accretion and lateral accretion correspond to the early and late stages of flood weakening, respectively. These stages cannot be effectively distinguished, which greatly increases the difficulty of understanding the reservoir characteristics. Another example involves cross-bedding and reactivation surfaces with similar sedimentary characteristics but different time backgrounds. The former indicates deposition within minutes, while the regular spacing between reactivation surfaces represents the periodic oscillations in river discharge during the depositional period [3; 24]. At present, the analytical methods applied in this field have not been applied in diverse environments [10] and structurally complex [27] braided river sedimentation systems to achieve the purpose of alluvial architecture prediction. The proposed and widely used hierarchical analysis approach is precisely in line with the needs of analyzing the architectural structure of complex sedimentary systems. This method was first proposed by [PERSON] [30] for the evaluation of fluvial sedimentation systems and further elaborated in work completed by [PERSON] [31], [PERSON] et al. [32], [PERSON] and [PERSON] [33], [PERSON] and [PERSON] [7], and [PERSON] et al. [8; 34].