## 2 Materials and Methods  
### Study Area and Data  
The study area is situated along the Shihutang navigation power section of the Ganjiang River in Ji'an City, Jiangxi Province, China (Figure 1). This river reach lies within a typical alluvial floodplain, characterized by soft surface sediments and deep fluvial deposits formed through prolonged erosion and deposition processes. The channel exhibitsa pronounced meandering \"S\"-shaped morphology, and the surrounding terrain is predominantly flat. The curved channel geometry induces spatial variability in hydrodynamic conditions. In particular, at meander bends ranging from 30\({}^{\circ}\) to 60\({}^{\circ}\), the flow velocity increases by up to 1.3 times relative to the upstream inflow, resulting in zones of enhanced shear stress. These areas are prone to intensified riverbed erosion, sediment resuspension, and localized siltation. Additionally, the Xiajiang Hydropower Project, situated approximately 95 km downstream, has disrupted the natural flow-sediment equilibrium, altering sediment transport pathways and deposition patterns in the reach.  
Given these geomorphological and hydraulic complexities, the Shihutang section of the Ganjiang River serves as a representative case for investigating sedimentation dynamics in inland waterways. It provides a practical foundation for modeling siltation processes and developing data-driven approaches to support channel maintenance, sediment risk assessment, and navigation safety.  
The spatial extent of the river channel and the study area boundary were delineated using satellite imagery solely for mapping and boundary definition purposes. This study employs three primary categories of data: bathymetric survey data, hydrological observations, and meteorological statistics. A comprehensive overview of all the data types, their sources, collection periods, and analytical applications is provided in Table 1.  
Bathymetric surveys were conducted using single-beam echo sounding on three occasions--1 April, 17 May, and 3 July 2024. High-density point measurements were systematically collected across the study area to capture detailed riverbed morphology. The raw depth data were subsequently resampled into a 30 m \(\times\) 30 m grid, generating gridded-scale bathymetric maps. By combining these measurements with concurrent water level observations from the Shihutang hub, grid-based water depth maps were derived. These datasets enabled a spatially explicit assessment of riverbed elevation and its temporal evolution (see Figure 2).  
The hydrological data consist of daily measurements aggregated at the reach scale, with one value per day for the entire study area. The variables include upstream and downstream water levels, threshold depths at both lock gates, inflow and outflow discharges, and navigational clearance heights. These parameters jointly characterize the hydraulic conditions governing sediment entrainment, transport, and deposition processes. The meteorological data were manually collected from publicly available weather websites  
Figure 1: Geographic location of the study area along the Ganjiang River, satellite image of the river channel, and structural schematic of the Shihutang navigation power hub.  
based on the geographic location of the study area. Four variables--maximum temperature, minimum temperature, wind speed, and sunshine duration--were compiled at a daily resolution, with one observation per variable per day for the entire reach. These factors influence river discharge and sediment dynamics by modulating evapotranspiration, runoff, and atmospheric forcing.