{"title":"Delineating individual alluvial fans and morphological analysis based on digital elevation models","authors":"Xingyu Zhou, Yang Chen, Wenjie Sun, Xin Yang, Yanxiang Wang, Chenrui Li, Guoan Tang","doi":"10.1016/j.geomorph.2025.109629","DOIUrl":null,"url":null,"abstract":"<div><div>Alluvial fans are common landforms deposited by streams and/or debris flows. Multiple fans can overlap and connect with each other, developing a bajada. Currently, studies about the evolutionary process of alluvial landscapes and environmental changes in arid areas urgently need clear, detailed and object-based evaluation within bajadas. However, existing methods still struggle to divide these alluvial slopes into individual fans. Accordingly, we proposed a novel method for delineating individual alluvial fans based on free digital elevation models. This method incorporated multi-directional hillshades to accurately extract alluvial slopes, and two flow direction algorithms to support the delineation of individual fans. The method was tested in Death Valley, where a total of 89 individual fans were delineated for morphological analysis. Our result demonstrated high accuracy validated by a Landset-9 L2 satellite image, with an intersection over union (IoU) of 95.51 % for alluvial slopes and a mean IoU of 86.19 % for individual fans, and it also aligned well with the geological map. Additionally, based on the delineated individual fans, we computed morphological features, distinguished the surface differences of both sides and analyzed the feature correlations. Overall, this study accomplished the delineation of individual fans and provided a viable solution for the automated and large-scale mapping of arid alluvial landscapes. The delineated results can act as the foundation for research about the evolutionary process and genetic mechanisms of alluvial fans, and provide opportunities for understanding the tectonic activities, sediment deposition and erosion process and environmental changes in arid regions.</div></div>","PeriodicalId":55115,"journal":{"name":"Geomorphology","volume":"473 ","pages":"Article 109629"},"PeriodicalIF":3.1000,"publicationDate":"2025-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Geomorphology","FirstCategoryId":"89","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0169555X2500039X","RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"GEOGRAPHY, PHYSICAL","Score":null,"Total":0}
引用次数: 0
Abstract
Alluvial fans are common landforms deposited by streams and/or debris flows. Multiple fans can overlap and connect with each other, developing a bajada. Currently, studies about the evolutionary process of alluvial landscapes and environmental changes in arid areas urgently need clear, detailed and object-based evaluation within bajadas. However, existing methods still struggle to divide these alluvial slopes into individual fans. Accordingly, we proposed a novel method for delineating individual alluvial fans based on free digital elevation models. This method incorporated multi-directional hillshades to accurately extract alluvial slopes, and two flow direction algorithms to support the delineation of individual fans. The method was tested in Death Valley, where a total of 89 individual fans were delineated for morphological analysis. Our result demonstrated high accuracy validated by a Landset-9 L2 satellite image, with an intersection over union (IoU) of 95.51 % for alluvial slopes and a mean IoU of 86.19 % for individual fans, and it also aligned well with the geological map. Additionally, based on the delineated individual fans, we computed morphological features, distinguished the surface differences of both sides and analyzed the feature correlations. Overall, this study accomplished the delineation of individual fans and provided a viable solution for the automated and large-scale mapping of arid alluvial landscapes. The delineated results can act as the foundation for research about the evolutionary process and genetic mechanisms of alluvial fans, and provide opportunities for understanding the tectonic activities, sediment deposition and erosion process and environmental changes in arid regions.
期刊介绍:
Our journal''s scope includes geomorphic themes of: tectonics and regional structure; glacial processes and landforms; fluvial sequences, Quaternary environmental change and dating; fluvial processes and landforms; mass movement, slopes and periglacial processes; hillslopes and soil erosion; weathering, karst and soils; aeolian processes and landforms, coastal dunes and arid environments; coastal and marine processes, estuaries and lakes; modelling, theoretical and quantitative geomorphology; DEM, GIS and remote sensing methods and applications; hazards, applied and planetary geomorphology; and volcanics.