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 downslop...

The effects of land cover and surface slope on lidar-derived elevation data were examined for a watershed in the piedmont of North Carolina. Lidar data were collected over the study area in a winter (leaf-off) overflight. Survey-grade elevation points (1,225) for six different land cover classes were used as reference points. Root mean squared error (RMSE) for land cover classes ranged from 14....

Variation in the computation of slope from digital elevation data can result in significantly different slope values and can, in turn, lead to widely varying estimates of environmental phenomena such as soil erosion that are highly dependent on slope. Ten methods of computing slope from distributed elevation data, utilizing capabilities inherent in five different geographic information systems ...

Geographical information systems (GIS) are proving to be very valuable tools in many natural resources applications such as hydrological modelling of terrain for water harvesting. The basic entity in such applications is the watershed which is either manually delineated on topographic map sheets or derived from digital elevation model (DEM) data using computational methods. A procedure for auto...

Digitized contours are increasingly being applied as a data source for generating regular grid digital elevation models (OEMs). The special characteristics of contours as a DEM data source, and some published contour-specific interpola tion algorithms, are reviewed in this paper. Test results for three algorithms are presented, employing both synthetic and real surface data. The algorithms are:...