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235
A New Method For The Determination Of Flow Directions And Upslope Areas In Grid Digital Elevation Models
 Water Resources Research
, 1997
"... A new procedure for the representation of flow directions and calculation of upslope areas using rectangular grid digital elevation models is presented. The procedure is based on representing flow direction as a single angle taken as the steepest downwards slope on the eight triangular facets center ..."
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Cited by 159 (2 self)
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A new procedure for the representation of flow directions and calculation of upslope areas using rectangular grid digital elevation models is presented. The procedure is based on representing flow direction as a single angle taken as the steepest downwards slope on the eight triangular facets centered at each grid point. Upslope area is then calculated by proportioning flow between two downslope pixels according to how close this flow direction is to the direct angle to the downslope pixel. This procedure offers improvements over prior procedures that have restricted flow to eight possible directions (introducing grid bias) or proportioned flow according to slope (introducing unrealistic dispersion). The new procedure is more robust than prior procedures based on fitting local planes while retaining a simple grid based structure. Detailed algorithms are presented and results are demonstrated through test examples and application to digital elevation data sets. Introduction Flow direct...
Mineral dust entrainment and deposition (DEAD) model: Description and 1990s dust climatology
 J. Geophys. Res
"... Abstract. We describe a model for predicting the sizeresolved distribution of atmospheric dust for climate and chemistryrelated studies. The dust distribution from 1990–1999 is simulated with our mineral aerosol entrainment and deposition module embedded in a chemical transport model. Mobilization ..."
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Cited by 125 (16 self)
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Abstract. We describe a model for predicting the sizeresolved distribution of atmospheric dust for climate and chemistryrelated studies. The dust distribution from 1990–1999 is simulated with our mineral aerosol entrainment and deposition module embedded in a chemical transport model. Mobilization processes include entrainment thresholds, moisture inhibition, drag partitioning, and saltation feedback. Soil erodibility is prescribed by a new physically based geomorphological index which is proportional to the runoff area upstream of each source region. Dry deposition processes include sedimentation and turbulent mixout. Nucleation scavenging and sizeresolved washout in both stratiform and convective cloud types are represented. Simulations of the 1990s broadly agree with station observations and satelliteinferred dust distributions. Without invoking anthropogenic mechanisms, the model captures the seasonal migration of the transAtlantic African dust plume, and the spring maximum in Asian dust outflow and concentration over the Pacific. We estimate the 1990s global annual mean and variability of m dust to be: Emissions, Tg yr; Burden, Tg; Optical depth at 0.63 m,. This emission, burden, and optical depth are significantly lower than some recent estimates. The model underestimates transport and deposition of East Asian and Australian dust to some regions of the Pacific Ocean. An underestimate of long range transport of particles larger than 3 m contributes to this bias. Our experiments support the hypothesis that dust emission “hot spots” exist in regions where alluvial sediments have accumulated and may be disturbed. 1.
D.,“Digital elevation model grid size,landscape representation, and hydrologic simulations”,
 Water Resour. Res.,
, 1994
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Modeling topographic potential for erosion and deposition using GIS
, 1996
"... . Modeling of erosion and deposition in complex terrain within a geographic information system (GIS) requires a high resolution digital elevation model (DEM), reliable estimation of topographic parameters, and formulation of erosion models adequate for digital representation of spatially distributed ..."
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Cited by 51 (3 self)
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. Modeling of erosion and deposition in complex terrain within a geographic information system (GIS) requires a high resolution digital elevation model (DEM), reliable estimation of topographic parameters, and formulation of erosion models adequate for digital representation of spatially distributed parameters. Regularized spline with tension was integrated within a GIS for computation of DEMs and topographic parameters from digitized contours or other point elevation data. For construction of flow lines and computation of upslope contributing areas an algorithm based on vectorgrid approach was developed. The spatial distribution of areas with topographic potential for erosion or deposition was then modeled using the approach based on the unit stream power and directional derivatives of surface representing the sediment transport capacity. Presented methods are illustrated on study areas in central Illinois and the Yakima Ridge, Washington. 1. Introduction Several erosion models ha...
Drainage Queries in TINs: From local to global and back again
 In Proc. 7th Int. Symp. on Spatial Data Handling
, 1996
"... This paper considers the cost of preprocessing a digital terrain model (DTM) represented as a triangulated irregular network (TIN) so that drainage queriese.g., what is the watershed of a query point, or how much water passes through a point given that rain is falling at a known ratecan be ans ..."
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Cited by 30 (6 self)
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This paper considers the cost of preprocessing a digital terrain model (DTM) represented as a triangulated irregular network (TIN) so that drainage queriese.g., what is the watershed of a query point, or how much water passes through a point given that rain is falling at a known ratecan be answered by simply evaluating a summary function. Although the worstcase storage and preprocessing costs are high, the experimentallyobserved costs are reasonable. In order to compute a compact and consistent summary function, the drainage network needs a rigorous definition. This paper, therefore, also surveys some of the previous definitions, extends them, and establishes a number of properties of drainage networks with a focus on TINs. 1 Introduction Terrain drainage characteristics provide important information on water resources, possible flood areas, erosion and other natural processes. In natural resource management, for example, the basic management unit is the watershed, the area a...
An ObjectOriented Framework for Distributed Hydrologic and Geomorphic Modeling Using Triangulated Irregular Networks
 Computers and Geosciences
, 1999
"... We describe a new set of data structures and algorithms for dynamic terrain modeling using a triangulated irregular networks (TINs). The framework provides an efficient method for storing, accessing, and updating a Delaunay triangulation and its associated Voronoi diagram. The basic data structure c ..."
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Cited by 30 (9 self)
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We describe a new set of data structures and algorithms for dynamic terrain modeling using a triangulated irregular networks (TINs). The framework provides an efficient method for storing, accessing, and updating a Delaunay triangulation and its associated Voronoi diagram. The basic data structure consists of three interconnected data objects: triangles, nodes, and directed edges. Encapsulating each of these geometric elements within a single data object makes it possible to essentially decouple the TIN representation from the modeling applications that make use of it. Both the triangulation and its corresponding Voronoi diagram can be rapidly retrieved or updated, making these methods well suited to adaptive remeshing schemes. We develop a set of algorithms for defining drainage networks and identifying closed depressions (e.g., lakes) for hydrologic and geomorphic modeling applications. We also outline simple numerical algorithms for solving networkrouting and 2D transport equations...
A fast, simple and versatile algorithm to fill the depressions of digital elevation models.
 Catena,
, 2002
"... Abstract The usual numerical methods for removing the depressions of a Digital Elevation Model Ž . DEM gradually fill the depressions and merge the embedded ones. These methods are complex to implement and need large computation time, particularly when the DEM contains a high proportion of random n ..."
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Cited by 30 (0 self)
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Abstract The usual numerical methods for removing the depressions of a Digital Elevation Model Ž . DEM gradually fill the depressions and merge the embedded ones. These methods are complex to implement and need large computation time, particularly when the DEM contains a high proportion of random noise. A new method is presented here. It is innovative because, instead of gradually filling the depressions, it first inundates the surface with a thick layer of water and then removes the excess water. The algorithm is simple to understand and to implement, requiring only a few tens of code lines. It is much faster than usual algorithms. Moreover, this method is versatile: depressions can be replaced with a surface either strictly horizontal, or slightly sloping. The first option is used for the calculation of depression storage capacity and the second one for drainage network extraction. The method is fully detailed and a pseudocode is provided. Its practical computation time, evaluated on generated fractal surfaces, is asymptotically proportional to N 1.2 where N is the number of grid points. The theoretical computation time is asymptotically proportional to N 1.5 in all cases, with the exception of some exotic ones with no practical interest. By contrast, existing methods have a computation time asymptotically proportional to N 2 . Applications are done for both generated and measured surfaces with 256 cells to 6.2 million cells. q
Spatial considerations for linking watershed land cover to ecological indicators in
, 2005
"... Abstract. Watershed land cover is widely used as a predictor of streamecosystem condition. However, numerous spatial factors can confound the interpretation of correlative analyses between land cover and stream indicators, particularly at broad spatial scales. We used a streammonitoring data set ..."
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Cited by 26 (2 self)
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Abstract. Watershed land cover is widely used as a predictor of streamecosystem condition. However, numerous spatial factors can confound the interpretation of correlative analyses between land cover and stream indicators, particularly at broad spatial scales. We used a streammonitoring data set collected from the Coastal Plain of Maryland, USA to address analytical challenges presented by (1) collinearity of landcover class percentages, (2) spatial autocorrelation of land cover and stream data, (3) intercorrelations among and spatial autocorrelation within abiotic intermediaries that link land cover to stream biota, and (4) spatial arrangement of land cover within watersheds. We focused on two commonly measured stream indicators, nitratenitrogen (NO 3 N) and macroinvertebrate assemblages, to evaluate how different spatial considerations may influence results. Partial correlation analysis of landcover percentages revealed that simple correlations described relationships that could not be separated from the effects of other landcover classes or relationships that changed substantially when the influences of other landcover classes were taken into account. Partial Mantel tests showed that all landcover percentages were spatially autocorrelated, and this spatial phenomenon accounted for much of the variation in macroinvertebrate assemblages that could naively be attributed to certain classes (e.g., percentage cropland). We extended our use of partial Mantel tests into a pathanalytical framework and identified several independent pathways between percentage developed land and instream measurements after factoring out spatial autocorrelation and other confounding variables; however, under these conditions, percentage cropland was only linked to nitrateN. Further analyses revealed that spatial arrangement of land cover, as measured by areal buffers and distance weighting, influenced the amount of developed land, resulting in a threshold change in macroinvertebrateassemblage composition. Moreover, distanceweighted percentage cropland improved predictions of stream nitrateN concentrations in small watersheds, but not in medium or large ones. Collectively, this series of analyses clarified the magnitude and critical scales of effects of different landcover classes on Coastal Plain stream ecosystems and may serve as an analytical framework for other studies. Our results suggest that greater emphasis should be placed on these important spatial considerations; otherwise, we risk obscuring the relationships between watershed land cover and the condition of stream ecosystems.
Applications of computational geometry in Geographic Information Systems
 Handbook of Computational Geometry
, 1997
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Geographical Information Systems and Dynamic Models
, 1995
"... Please refer to this publication as: ..."