Primary topographic attributes play a critical role in determining watershed hydrologic characteristics for water resources modeling with raster-based digital elevation models (DEM). The effects of DEM resolution on a set of important topographic derivatives are examined in this study, including slope, upslope contributing area, flow length and watershed area. The focus of the study is on how s...

In several GIS applications it is necessary to classify the topographic surface represented by a Digital Elevation Model (DEM) into specific slope classes. However, the computation of these classes from a DEM is influenced by the uncertainty in the elevations of those models. Monte-Carlo method has been used to study the effect of DEM uncertainty on topographic parameters. This method requires ...

A 2D laser-scanner was deployed at the high tide runup limit of a pure gravel beach (Loe Bar, Cornwall, England) to measure high-frequency (2.5 Hz) swash hydrodynamics and topographic changes during an energetic wave event. Measurements performed with the laser-scanner were corrected to compensate for levelling and orientation errors, and a variance threshold was applied to separate the beach t...

We combined normalized difference vegetation index (NDVI) and digital terrain analysis to detect thermal south (defined in this paper as the warmest slope azimuth, especially for plant growth) in three mountainous landscapes of California. Two methods, respectively, defined topography-controlled thermal south as corresponding to (1) the maximum NDVI contrast between opposite topographic aspects...

Reducing scatter in measurements of regional-phase amplitude ratios is desirable for seismic discrimination applications and also provides insight into crustal structure controls on energy partitioning of regional seismic waves. Our previous analysis (Fan and Lay, 1998) of the regional seismic discriminant, Pg/Lg, indicated that variations in crustal structure cause path-specific fluctuations o...

The high-salinity water flowing out of the Mediterranean Sea descends to mid depths in the density-stratified ocean, continues as a narrow jet along the Iberian continental slope, and intermittently detaches large-scale eddies (called "Meddies"). This process is important because it maintains the relatively high mean salinity of a major water mass (the "Mediterranean Intermediate Water") in the...

Laboratory experiments are performed to examine gravity currents propagating into an ambient of uniformly decreasing depth. Predominantly, the study is of a surface gravity current shoaling over a bottom slope as it approaches a corner between the horizontal surface and the sloping topography. For sufficiently high Reynolds number currents, they are found to propagate at a constant speed over t...

land cover map is important for many urban planning and management activities. in this study, in order to produce land cover map of arak city, digital image of liss-iii scanner acquired on 16 june 2006 were employed. first of all, geometric correction with rmse 0.58 pixel was applied. considering the mountainous condition of the study area, topographic correction was applied to the image. in su...

Topographic metrics are designed to quantify scale-relevant relationships between geometric properties of landscapes reveal the processes shaping them. They have long been derived from topographic flow routing algorithms, initially developed for coarse Digital Elevation Models (DEMs), whose resolution (≥30 m) and poor precision did not resolve correctly patterns channel width. Since high DEMs m...