# Study on Temporal and Spatial Distribution of Landslides in the Upper Reaches of the Yellow River
## 3 Temporal and Spatial Distribution of Landslides in the Upper Reaches of the Yellow River  
### Material and Methods  
The process of remote sensing interpretation and recognition of regional landslide disasters mainly includes five parts: image preprocessing, establishment of interpretation \begin{table}
\begin{tabular}{c c c c} \hline \hline
**System** & **Series** & **Sign** & **Sedimentary Facies and Material Composition** \\ \hline \multirow{6}{*}{Holocene} & & & Wind phase \\  & & & It is composed of beige medium and fine quartz sand (more than \\  & \(\mathrm{Q_{4}}^{\mathrm{eol}}\) & 80\%) and a small amount of dark minerals. The gravel is round and \\  & & the particle size is generally greater than 0.5 mm. The thickness is \\  & & & generally 20–40 m. \\ \cline{2-4}  & & & Pluvial phase \\  & & & The lithology is mainly breccia, gravel and sand, with sub-sand lens. \\  & & & The sorting and roundness are poor, and the thickness is 12–30 m. \\ \cline{2-4}  & & & Alluvial-diluvial facies \\  & & & The lithology is gray and soil gray sand gravel layer with sand lens, \\  & & & and the upper part is fine sand. The structure is loose and the \\  & & & thick-ness changes greatly, generally 10–30 m. \\ \cline{2-4}  & & & Alluvial phase \\  & & & It is mainly composed of riverbed sand gravel pebble layer and \\  & & & floodplain silty sand, fine sand, sandy soil, clay and so on. Gravel \\  & & & sorting, roundness is better, generally 5–10 cm. The thickness is \\  & & & generally 10–20 m. \\ \hline \multirow{6}{*}{Quaternary} & & & Wind phase \\  & & & Earthy yellow, light grayish yellow silt. The silt content is more than \\  & & & 70\%, with macropores and vertical joints. The thickness is 50–260 m. \\ \cline{2-4}  & & & Alluvial-diluvial facies \\  & & & Gray gravel, sand and sub-clay layers. The sorting and roundness are \\  & & & poor, the gravel composition varies from place to place, and the \\  & & & thickness is generally greater than 30 m. \\ \cline{2-4}  & & & Pluvial phase \\  & & & The gray-soil gray sand-gravel layer is sandwiched with gravel-sand \\  & & & lens. The gravel composition is complex, mostly angular, \\  & & & sub-angular, muddy and sandy filling, 30–60 m thick, medium \\  & & & density. The thickness is generally greater than 30 m. \\ \cline{2-4}  & & & Alluvial phase \\  & & & It is composed of a set of alluvial facies, the lower part is gravel layer, \\  & & & and the upper part is fine sand and silt, loess, loess-like clay layer, \\  & & & with a thickness of 5–30 m. \\ \hline \multirow{6}{*}{Middle Pleistocene} & & & Ice-water phase accumulation \\  & & & The lithology is gray-yellow sandstone, slate, granite, etc., which are \\  & & & poorly sorted and rounded. The mud gravel and sand gravel layer \\  & & & composed of gravel and sand, with a layer of yellow sandy soil, \\  & & & 5–15 m thick. \\ \hline \multirow{6}{*}{Lower Pleistocene} & & & The Gonghe Basin is a set of yellow and grayish yellow silty \\  & & & mud-stone, siltstone mixed with colored fine sandstone and \\ \cline{1-1}  & & & sand-containing gravel lens. \\ \cline{1-1}  & & & The area of Yezangcaotan and Yelangtan in Guide Basin is a set of \\ \cline{1-1}  & & & conglomerate and fine siltstone with sandstone, which is generally \\ \cline{1-1}  & & & exposed at an altitude of 2800–3300 m. \\ \cline{1-1}  & & & Leyangang in Hualong Basin is a set of gray-white-light \\ \cline{1-1}  & & & orange-yellow conglomerate, glutenite with thin sandstone and \\ \cline{1-1}  & & & mudstone. The thickness is 206–405 m. \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Quaternary strata and lithology in the study area. marks, image segmentation, image classification, and accuracy evaluation. The image preprocessing of this study is carried out in the environment for visualizing images (ENVI) 5.3 software, and the image segmentation, classification, and accuracy evaluation are completed in the e-Cogniton 9.0 software.