scholarly journals A semi-automated method for extracting channels and channel profiles from lidar-derived digital elevation models

Geosphere ◽  
2020 ◽  
Vol 16 (3) ◽  
pp. 806-816
Author(s):  
Pinliang Dong ◽  
Ruofei Zhong ◽  
Jisheng Xia ◽  
Shucheng Tan
Keyword(s):  
High Resolution ◽  
Accuracy Assessment ◽  
Digital Elevation Models ◽  
Stream Channels ◽  
Channel Detection ◽  
Automated Method ◽  
San Andreas ◽  
Digital Elevation ◽  
Processing Techniques ◽  
User Friendly

Abstract With the advent of digital elevation models (DEMs) and geographic information systems (GIS), several methods have been proposed to extract channels from raster DEMs. Light detection and ranging (lidar) can produce high-resolution DEMs and poses new challenges to existing methods for channel extraction. This paper introduces a semi-automated method for extracting stream channels and channel profiles from high-resolution DEMs using image processing techniques. Based on user-specified approximate locations of start and end points and a few simple parameters, the method implements five automated steps: (1) channel detection using a local minimum value search; (2) channel delineation using Bresenham’s line algorithm and mathematical morphological operation; (3) vectorization; (4) profile generation; and (5) accuracy assessment. The method is implemented as an ArcGIS Python add-in toolbar named Channel Extraction. The application of the toolbar is demonstrated using a lidar-derived DEM in a study area along the San Andreas fault in California, USA. The software and test data are freely available for download (see Supplemental Files1). The demonstrated samples suggest that this new semi-automated method for extracting channels and channel profiles is flexible and user-friendly and can produce accurate results to support geomorphic studies.

scholarly journals Improving forest operations planning through high-resolution flow-channel and wet-areas mapping

2008 ◽  
Vol 84 (4) ◽  
pp. 568-574 ◽  
Author(s):  
Paul N.C. Murphy ◽  
Jae Ogilvie ◽  
Mark Castonguay ◽  
Cheng-fu Zhang ◽  
Fan-Rui Meng ◽  
...  
Keyword(s):  
Surface Water ◽  
High Resolution ◽  
Digital Elevation Models ◽  
Flow Channel ◽  
Tree Planting ◽  
Gps Tracking ◽  
Stream Channels ◽  
Forest Operations ◽  
Operations Planning ◽  
Digital Elevation

This article describes a mapping process designed to provide forest management with high-resolution flow-channel and wet-area maps for forest operations planning. The process requires digital elevation models (DEMs) and hydrographic data, and also portrays the likely depth to surface water across forested terrains away from any nearest surface-water features such as streams, rivers, lakes, and wetlands. Map applications involve layout of roads and trails, automated selection of best road–stream crossings, minimizing earth-moving operations during road construction, detailing in-block plans for temporary roads and channel crossings, and delineating habitats, machine-free zones and blocks for harvesting, tree planting, site preparation, and stand thinning. Map verifications centre on visual comparisons of map features with land-surface images, and these can be coupled with GPS tracking of wetland and wet-area borders, stream channels, and road-stream crossings. Further developments involve increasing the wet-areas map resolution and accuracy with LiDAR (Light Detection and Ranging) bare-ground DEMs and other fine-gridded DEMs, and expanding the applications to mapping of soils, soil properties and tree and crop productivity, to watershed and road-network management, to off-road trafficability, and to impact evaluations dealing with hydrological sensitivities and risks. Key words: forest operations planning, geographic information systems, digital elevation models, flow-channels, wet areas and depth-to-water maps, hydrological risks

scholarly journals Accuracy Assessment of Digital Elevation Models Produced From Different Geomatics Data

2020 ◽  
Vol 38 (11A) ◽  
pp. 1580-1592
Author(s):  
Imzahim A. Alwan ◽  
Zina W. Samueel ◽  
Qassim K. Abdullah
Keyword(s):  
High Resolution ◽  
Open Source ◽  
Accuracy Assessment ◽  
Digital Elevation Models ◽  
Ground Cover ◽  
Interferometric Synthetic Aperture Radar ◽  
Sensing Applications ◽  
Digital Elevation ◽  
Source Models ◽  
Remote Sensing Applications

Digital Elevation Models (DEM) are now being used in several geospatial applications. DEMs play an important role in the preliminary surveys for constructing dams and reservoirs, highways, canals, and projects in which earth work is essential. In many remote sensing applications, DEMs have become a significant tool for InSAR (Interferometric Synthetic Aperture Radar) processing, ground cover classification and images ortho-rectification. In this study, the accuracy of DEMs obtained from ALOS V1.1, ASTER V2, SRTM V3 and other obtained from a pair of Pleiades high-resolution (PHR) 1B satellites in a study area were evaluated after comparing them with high accuracy GNSS/RTK checkpoints. The SRTM3, ALOS V1.1, ASTER V2 DEM revealed a Root Mean Square Error (RMSE) of 2.234m, 0.838m, and 15.116m respectively; while the DEM which is produced from a 0.5m resolution of Pleiades 0.5m shows an RMSE of 0.642m. The correct bias Linear transformation algorithm was used and the RMSE results were: SRTM V3 (1.319m), ALOS V1.1 (0.830m), ASTER V2 (3.815m), and PHR (0.433m). The results showed that the ALOS V1.1 model is the most accurate of the open source models followed by the SRTM V3 model and then followed by ASTER V2. The results obtained from a pair by Pleiades high-resolution (PHR) 1B satellites show a higher accuracy than the results obtained from the open source models.

scholarly journals Glacier elevation and mass changes over the central Karakoram region estimated from TanDEM-X and SRTM/X-SAR digital elevation models

2016 ◽  
Vol 57 (71) ◽  
pp. 273-281 ◽  
Author(s):  
Melanie Rankl ◽  
Matthias Braun
Keyword(s):  
High Resolution ◽  
Snow Cover ◽  
Digital Elevation Models ◽  
Mass Balances ◽  
Freshwater Resources ◽  
Digital Elevation ◽  
Glacier Changes ◽  
Kinematic Waves ◽  
Elevation Changes ◽  
River Communities

AbstractSnow cover and glaciers in the Karakoram region are important freshwater resources for many down-river communities as they provide water for irrigation and hydropower. A better understanding of current glacier changes is hence an important informational baseline. We present glacier elevation changes in the central Karakoram region using TanDEM-X and SRTM/X-SAR DEM differences between 2000 and 2012. We calculated elevation differences for glaciers with advancing and stable termini or surge-type glaciers separately using an inventory from a previous study. Glaciers with stable and advancing termini since the 1970s showed nearly balanced elevation changes of -0.09 ±0.12 m a-1 on average or mass budgets of -0.01 ±0.02Gt a-1 (using a density of 850 kg m-3). Our findings are in accordance with previous studies indicating stable or only slightly negative glacier mass balances during recent years in the Karakoram. The high-resolution elevation changes revealed distinct patterns of mass relocation at glacier surfaces during active surge cycles. The formation of kinematic waves at quiescent surge-type glaciers could be observed and points towards future active surge behaviour. Our study reveals the potential of the TanDEM-X mission to estimate geodetic glacier mass balances, but also points to still existing uncertainties induced by the geodetic method.

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