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Environmental Applications of Digital Terrain Modeling von Wilson, John P. (eBook)

  • Verlag: Wiley-Blackwell
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Environmental Applications of Digital Terrain Modeling

A digital elevation model (DEM) is a digital representation of ground surface topography or terrain. It is also widely known as a digital terrain model (DTM). A DEM can be represented as a raster (a grid of squares) or as a vector based triangular irregular network (TIN). DEMs are commonly built using remote sensing techniques, but they may also be built from land surveying. DEMs are used often in geographic information systems, and are the most common basis for digitally-produced relief maps. The terrain surface can be described as compromising of two different elements; random and systematic. The random (stochastic) elements are the continuous surfaces with continuously varying relief. It would take an endless number of points to describe exactly the random terrain shapes, but these can be described in practice with a network of point. It is usual to use a network that creates sloping triangles or regular quadrants. This book examines how the methods and data sources used to generate DEMs and calculate land surface parameters have changed over the past 25 years. The primary goal is to describe the state-of-the-art for a typical digital terrain modeling workflow that starts with data capture, continues with data preprocessing and DEM generation, and concludes with the calculation of one or more primary and secondary land surface parameters. Taken as a whole, this book covers the basic theory behind the methods, the instrumentation, analysis and interpretation that are embedded in the modern digital terrain modeling workflow, the strengths and weaknesses of the various methods that the terrain analyst must choose among, typical applications of the results emanating from these terrain modeling workflows, and future directions. This book is intended for researchers and practitioners who wish to use DEMs, land surface parameters, land surface objects and landforms in environmental projects. The book will also be valuable as a reference text for environmental scientists who are specialists in related fields and wish to integrate these kinds of digital terrain workflows and outputs into their own specialized work environments. Dr. John P. Wilson is Professor of Spatial Sciences in the Dana and David Dornsife College of Letters, Arts and Sciences at the University of Southern California (USC) where he directs the Spatial Sciences Institute as well as the Geographic Information Science & Technology (GIST) Graduate Programs and GIS Research Laboratory, and also holds adjunct appointments as Professor in the School of Architecture and in the Viterbi School of Engineering???s Departments of Computer Science and Civil & Environmental Engineering.

Produktinformationen

    Format: ePUB
    Kopierschutz: AdobeDRM
    Seitenzahl: 360
    Sprache: Englisch
    ISBN: 9781118938171
    Verlag: Wiley-Blackwell
    Größe: 10364 kBytes
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Environmental Applications of Digital Terrain Modeling

List of Figures

1.1 Scales at which various biophysical processes dominate calculation of primary environmental regimes. 1.2 Map of Cottonwood Creek, MT study site. 1.3 NED 10-m contour and NHD-Plus streamline data for the Cottonwood Creek, MT study site, with the catchment boundary overlaid. 2.1 The main tasks associated with digital terrain modeling. 2.2 The three principal methods of structuring an elevation data network: (a) a contour-based network; (b) a square-grid network showing a 3×3 moving window; and (c) a triangulated irregular network (TIN). 2.3 Streamline data in green and (a) initial gridded streamlines at 1-second resolution in red and (b) adjusted gridded streamlines at 1-second resolution in red. 3.1 Schematic showing site-specific, local, and regional interactions as a function of time. 3.2 A 3×3 moving grid used to calculate selected local land surface parameters. 3.3 Node numbering convention used for calculation of local land surface parameters. 3.4 Percent slope grid derived for Cottonwood Creek, MT study site using the finite difference equation, with the catchment boundary overlaid. 3.5 Aspect in degrees from north derived for Cottonwood Creek, MT study site using the finite difference equation, with the catchment boundary overlaid. 3.6 Northness derived for Cottonwood Creek, MT study site, with the catchment boundary overlaid. 3.7 Eastness derived for Cottonwood Creek, MT study site, with the catchment boundary overlaid. 3.8 Profile curvature (radians per 100m, convex curvatures are positive) derived for Cottonwood Creek, MT study site using the finite difference formula, with the catchment boundary overlaid. 3.9 Plan curvature (radians per 100m, convex curvatures are positive) derived for Cottonwood Creek, MT study site using the finite difference formula, with the catchment boundary overlaid. 3.10 Single- and multiple-flow directions assigned to the central grid cell in a 3×3 moving window using the D8 and FMFD flow-direction algorithms. Gray shading represents elevation decreasing with the darkness of the cell. Multiple-flow directions are assigned in (b) and a fraction of the flow of the central cell is distributed to each of the three cells that the arrows point to. 3.11 Concept of flow apportioning in D. 3.12 Upslope contributing area (ha) derived for Cottonwood Creek, MT study site using the D8 single-flow direction algorithm, with the catchment boundary overlaid. 3.13 Upslope contributing area (ha) derived for Cottonwood Creek, MT study site using the D single-flow direction algorithm, with the catchment boundary overlaid./

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