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The North America elevation data were derived from the GTOPO30 elevation dataset (http://eros.usgs.gov/products/elevation/gtopo30.html) produced by the U.S. Geological Survey and from the Canada3D elevation dataset produced by the Centre for Topographic Information (Sherbrooke), Natural Resources Canada. GTOPO30 is a global digital elevation model (DEM) with a horizontal grid spacing of 30 arc seconds (approximately 1 kilometer). GTOPO30 was derived from several raster and vector sources of topographic information. It was developed between 1993 and 1996 through a collaborative effort led by staff at the U.S. Geol The North America elevation data were derived from the...
Mapping salt-affected soils in remote rangelands is challenging. We used Landsat 7 ETM data to facilitate digital mapping of gypsic and natric soil areas in the upper Colorado River drainage. Optimum index factor band combinations were used to explore the scene. Normalized difference ratio models and threshold values were developed by comparing spectral signatures with gypsic and natric soil areas verifi ed in the fi eld. Gypsic soil areas were mapped using the normalized difference ratio of Bands 5 and 7 with a threshold >0.11, probably related to the spectral refl ectance of gypsum within a few centimeters of the surface. All sites predicted to be gypsic soil areas were determined to be gypsic by fi eld assessment,...
Stream power can be an extremely useful index of fluvial sediment transport, channel pattern, river channel erosion and riparian habitat development. However, most previous studies of downstream changes in stream power have relied on field measurements at selected cross-sections, which are time consuming, and typically based on limited data, which cannot fully represent important spatial variations in stream power. We present here, therefore, a novel methodology we call CAFES (combined automated flood, elevation and stream power), to quantify downstream change in river flood power, based on integrating in a GIS framework Flood Estimation Handbook systems with the 5 m grid NEXTMap Britain digital elevation model...