Abstract
High-resolution digital elevation models (HR-DEMs) originating from airborne laser scanning (ALS) point clouds must be transformed into Culvert-modified DEMs for hydrological and geomorphological analysis. To produce a culvert-modified DEM, information on the locations of drainage structures (DSs) (e.g., bridges and culverts) is essential. Nevertheless, DS mapping techniques, whether in connection with the development of new methods or an application setting of existing methods, have always been complicated. Consequently, wide area DS data are rare, making it challenging to produce a culvert-modified DEM in a wide area capacity. Alternatively, the breach algorithm (BA) method is a standard procedure to obtain culvert-modified DEMs in the absence of DS data, solving the problem to some extent. This paper addresses this shortcoming using a newly developed drainage structure mapping algorithm (DSMA) for obtaining a culvert-modified DEM for an area of 36 km2 in Vermont, USA. Benchmark DS data are used as a standard reference to assess the performance of the DSMA method compared to the BA method. A consistent methodological framework is formulated to obtain a culvert-modified DEM using DS data, mapped using the DSMA and resultant culvert-modified DEM is then compared with BA method respectively. The DSs found from the culvert-modified DEMs were reported as true positive (TP), false positive (FP), and false negative (FN). Based on TP, FP, and FN originating from the culvert-modified DEMs of both methods, the evaluation metrics of the false positive rate (FPR) (i.e., the commission error) and false negative rate (FNR) (i.e., the omission error) were computed. Our evaluation showed that the newly developed DSMA-based DS data resulted in an FPR of 0.05 with federal highway authorities (FHWA) roads and 0.12 with non-FHWA roads. The FNR with FHWA roads was 0.07, and with non-FHWA roads, it was 0.38. The BA method showed an FPR of 0.28 with FHWA roads and 0.62 with non-FHWA roads. Similarly, the FNR for the BA method was 0.32 with FHWA roads and 0.61 with non-FHWA roads. The statistics based on the FPR and FNR showed that the DSMA-based culvert-modified DEM was more accurate compared with the BA method, and the formulated framework for producing culvert-modified DEMs using DSMA-based DS data was robust.
Highlights
High-resolution (HR) digital elevation models (DEMs) deciphering the fundamental earth surface processes are in frequent use and obtained from three-dimensional (3D) clouds of laser point measurements, comprising dense sampling rates (e.g., 230 laser return from a1 m2 area) [1,2]
federal highway authorities (FHWA) and non-FHWA roads were combined into single-road centerline data at the preprocessing stage. (b) the breaching algorithm (BA) method was applied to the High-resolution digital elevation models (HR-DEMs) for creating a culvert-modified DEM. (c) The drainage structure mapping algorithm (DSMA) method was applied to the HR-DEM for creating a culvert-modified DEM. (d) The total number of drainage structures (DSs) in terms of true positive (TP), false positive (FP), and false negative (FN), originating from the culvert-modified DEMs of (b) and (c), was calculated using the benchmark DS dataset as a standard reference
A newly developed DSMA0 s performance was assessed in the context of producing a culvert-modified DEM compared to the breaching algorithm (BA) method
Summary
High-resolution (HR) digital elevation models (DEMs) deciphering the fundamental earth surface processes are in frequent use and obtained from three-dimensional (3D) clouds of laser point measurements, comprising dense sampling rates (e.g., 230 laser return from a1 m2 area) [1,2]. High-resolution (HR) digital elevation models (DEMs) deciphering the fundamental earth surface processes are in frequent use and obtained from three-dimensional (3D) clouds of laser point measurements, comprising dense sampling rates An HR-DEM could adopt certain variants where each variant serves a different purpose in a particular application setting [7]. Airborne laser scanning (ALS) ground points are interpolated to create an HR-DEM, deciphering the Earth’s surface for cartographic purposes (e.g., urban planning and making contour maps) [8]. In the application setting of hydrology and geomorphology, HR-DEM processing must be done by incorporating some additional yet important data such as drainage structures (DSs) (e.g., bridges and culverts) so that watercourses (e.g., rivers and streams) and watershed areas can be delineated accurately [9]
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