Abstract
The morphological characteristics of yardangs are the direct evidence that reveals the wind and fluvial erosion for lacustrine sediments in arid areas. These features can be critical indicators in reconstructing local wind directions and environment conditions. Thus, the fast and accurate extraction of yardangs is key to studying their regional distribution and evolution process. However, the existing automated methods to characterize yardangs are of limited generalization that may only be feasible for specific types of yardangs in certain areas. Deep learning methods, which are superior in representation learning, provide potential solutions for mapping yardangs with complex and variable features. In this study, we apply Mask region-based convolutional neural networks (Mask R-CNN) to automatically delineate and classify yardangs using very high spatial resolution images from Google Earth. The yardang field in the Qaidam Basin, northwestern China is selected to conduct the experiments and the method yields mean average precisions of 0.869 and 0.671 for intersection of union (IoU) thresholds of 0.5 and 0.75, respectively. The manual validation results on images of additional study sites show an overall detection accuracy of 74%, while more than 90% of the detected yardangs can be correctly classified and delineated. We then conclude that Mask R-CNN is a robust model to characterize multi-scale yardangs of various types and allows for the research of the morphological and evolutionary aspects of aeolian landform.
Highlights
Yardangs are wind-eroded ridges carved from bedrock or cohesive sediments, and are found broadly in arid environments on Earth [1,2,3,4], other planets including Mars [5,6,7], Venus [8,9] and Saturn’s largest moon Titan [10]
A true positive (TP) indicates a correctly detected yardang and a false positive (FP) indicates a wrongly detected yardang, which belongs to the background
The experimental results indicate that the Mask R-convolutional neural networks (CNNs) can successfully extract the features of yardangs from the training dataset
Summary
Yardangs are wind-eroded ridges carved from bedrock or cohesive sediments, and are found broadly in arid environments on Earth [1,2,3,4], other planets including Mars [5,6,7], Venus [8,9] and Saturn’s largest moon Titan [10]. Yardangs usually occur in groups and display a wide variety in scales and morphologies in different locations [11]. The morphologies of yardangs are the feedback results of the topographies, wind regimes and sediment types when they formed, which makes them critical paleoclimatic and paleoenvironmental indicators [12,13,14]. Significant work has been done regarding yardang morphologies and their spatial distributions, evolution processes and controlling factors [5,12,15,16,17,18,19,20,21]. The rapid development of remote sensing (RS) technologies has enabled the observation and measurement of yardangs at various spatial scales. Al-Dousari et al [12]
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