# The Influence of Glacier Mass Balance on River Runoff in the Typical Alpine Basin
## 1 Introduction
InSAR (Interferometric Synthetic Aperture Radar), with its capability for all-weather, all-climate, and nighttime observations, has facilitated the generation of a global high-resolution DEM [22; 23]. The SRTM (Shuttle Radar Topography Mission) DEM is a typical representation of InSAR-derived elevation products. Depending on the resolution, it is available in both the 90 m and 30 m versions. The NASA(National Aeronautics and Space Administration) DEM was created by reprocessing the SRTMGL1V003 radar data and the modernization of the digital elevation model with improved accuracy by incorporating auxiliary data from the ASTER GDEM(Advanced Spaceborne Thermal Emission and Reflection Radiometer Global Digital Elevation Model), ICESat/GLAS, and PRISM(Panchromatic Remote-sensing Instrument for Stereo Mapping) datasets [24]. It can be stated that the NASA DEM is a further improvement of the SRTM DEM, particularly in high mountain regions, where the overall accuracy and quality of the NASA DEM surpasses that of the SRTM DEM. The ALOS-PALSAR (Advanced Land Observing Satellite--Phased Array type L-band Synthetic Aperture Radar) DEM data, with a resolution of 12.5 m, possess multiple characteristics, including high resolution, detailed terrain, and minimal influence from surface coverage. It has been widely applied in various fields [25]. The HMA (High Mountain Asia Digital Elevation Model) DEM also has a high resolution, but its coverage in the Pamir Plateau region is not comprehensive [26]. The TanDEM-X DEM has a resolution of 90 m and is generated from X-band interferometric radar data collected by the TanDEM-X and TerraSAR-X satellite constellation. On the other hand, ASTER GDEM is derived from more than 1.5 million scenes of ASTER optical images using stereo-correlation techniques, with a spatial resolution of 30 m [27]. DEM data generated by stereophotogrammetry also include the SPOT (Systeme Pour l'Observation de la Terre) DEM, ZY-3, and Gaofen-7. Because photogrammetry is susceptible to the influence of natural factors, while SAR, relying on its radar advantages, has a certain ability to penetrate through clouds and snow, InSAR has been widely applied for monitoring surface elevation changes in high-altitude or polar glacier areas [28; 29]. The emergence of high-resolution SAR has filled the gaps in monitoring GSE changes that were limited by laser altimetry satellites. The multi-source DEM differencing method utilizes traditional geodetic surveying techniques to compare DEM data from different time periods, thereby obtaining changes in GSE. By combining glacier area data, the method also estimates change in glacier volume, leading to the determination of GMB. GMB is an important aspect of glacier climate change research [30; 31]. To accurately assess the change in GMB, parameters such as snow density and ice density are often incorporated to estimate the glacier runoff. Glacier runoff and GMB are inherently connected, with the former defined as the impact on basin hydrology through the temporary storage and release of water at different time scales [32]. The latter reflects the response of glaciers to climate change and controls changes in the runoff and glacier [33]. Currently, various methods and techniques, including ground observations, remote-sensing technology, and model predictions, are widely employed for monitoring and analyzing GMB and glacier runoff [34]. These methods provide valuable data on the spatiotemporal variations of glacier runoff, enabling a better understanding of the relationship between them. GMB and glacier runoff are influenced by multiple factors, including climate change, precipitation, temperature, and more. To better predict future changes in glacier mass balance and glacier runoff, the use of climate models, hydrological models, and biophysical models for simulation and prediction is a valuable approach for studying hydrological changes [35; 36; 37].