## 1 Introduction  
Saline soil is a collective term that encompasses various types of soils, including salinized soils and alkaline soils. These soils are characterized by a high concentration of soluble salt ions, which adversely affect their physical, chemical, and biological properties, as well as plant growth [1]. Soil salinization, on the other hand, refers to the process by which soluble salts accumulate in the soil, leading to a deterioration of its fundamental characteristics and quality. As integral components of the ecosystem, the unique physico-chemical and biological properties of saline soils often result in atypical material and energy cycling processes, ultimately causing the wastage of agricultural resources, the fragility of ecosystems, economic losses, and secondary hazards [2]. Various methods and platforms have been employed to quantify salt content at different soil depth intervals. Traditional field investigations involve soil sampling and laboratory analysis. Additionally, near-end sensing electromagnetic techniques are widely utilized for soil salinity characterization at the field scale, significantly reducing the time required for field sampling [3]. However, these techniques are limited in their ability to map soil salinity across large areas and over time. In contrast, satellite remote sensing methods can provide extensive information about soils and offer notable advantages over traditional field surveys or near-end soil sensing surveys, including wide spatial coverage, high resolution, and periodic measurements [4; 5]. Saline soils typically exhibit higher reflectance than non-saline soils [6], and the accumulation of salt on the soil surface can theoretically be detected using remote sensing images [7]. Different saline soil minerals exhibit varying binding properties regarding moisture retention and lattice structure, resulting in distinct degrees and types of salinization that demonstrate different reflection and absorption characteristics. Studies have shown that saline soils possess significant absorption properties within the VNIR (400-1000 nm) and SWIR (900-1700/2500 nm) spectral range [8]. Additionally, soil salinity alters both soil color and surface roughness, with reflectance generally increasing as salt content rises. This spectral representation of saline soils facilitates monitoring through in situ and indoor VNIR techniques [9]. Furthermore, soils with varying salinity levels exhibit different thermal infrared emission properties influenced by soil moisture, fundamental harmonic vibrations of saline minerals, and ionic absorption characteristics. Existing research has confirmed a positive correlation between salt content and soil emissivity, with FTIR thermal infrared emission spectra in the range of 8-11 \(\upmu\)m recognized for their ability to identify salts and their concentrations [1]. Monitoring soil salinity using aerial photographs typically involves combining regional geomorphological characterization with color and textures, effectively identifying surface salt crusts and cracking through simple band reorganization and in situ work [10]. Multispectral sensors are predominantly utilized in airborne and satellite-based remote sensing platforms. These sensors enable the acquisition of soil reflectance across various spectral channels (e.g., blue, green, red, red-edge, near-infrared, short-wave infrared, and other bands), thereby facilitating statistical characterization of the relationship between soil salinity and spectral data [11]. Salinity-affected soils exhibit a stronger spectral response in the VNIR region compared to non-saline soils. Given their wide field of view, real-time information acquisition, and periodic surface coverage capabilities, multispectral remote sensing represents the most widely utilized technological tool for large-scale soil salinity monitoring today [12]. Over the past decade, remote sensing has proven effective in monitoring soil salinization through surface features at various scales.