The composite imagery dataset of Landsat in Nepal and Gyirong County

To support disaster assessment and post‑event research, this dataset comprises pre‑event composite images generated from Landsat satellite imagery, covering the entire territory of Nepal and the Gyirong County area in Tibet, China. These composites clearly depict the land surface conditions before the disaster (i.e., prior to 26 August 2026). The Landsat satellite carries the Operational Land Imager (OLI) sensor, which offers a spatial resolution of 30 metres and a revisit cycle of 16 days. The Landsat series of satellites has accumulated over 50 years of Earth observation data, making it one of the longest time‑series and most widely used medium‑resolution remote sensing data sources globally. Its multispectral bands cover visible, near‑infrared, and shortwave infrared wavelengths, providing excellent capabilities for identifying vegetation cover, soil moisture, lithological characteristics, and water body distribution. It can effectively reflect the land cover types, vegetation conditions, and topographic features prior to the debris flow event, thus serving as critical data support for disaster background analysis.