Raster_StreamExtractionService
Operation:
curvatureBasedMethod - Derive stream network from DEM based on topographic curvature. Use morphology based algorithm to compute curvature and flow accumulation, then threshold them to derive stream network. The processing could be slow and lengthy.
Our basic processing as follows:
- Use tardem program flood fill the depressions in DEM
- Use tardem program d8 to get flowdirection based on filled dem
- Execute morphology based algorithm program [Molloy and Stepinski, 2007] to get the curvature and threshold the curvature. This program uses a polynomial approximation to the local patch of the surface defined on a 5×5 cells neighborhood centered on a focus cell
- Run tardem program aread8 to get flow accumulation using channel segment as weight(derived from threholding curvature grid)
- Use GRASS command r.mapcalc to threshold flow accumulation to get stream
Request Parameters:
- sourceURL
- URL of input elevation file
- Default format: GeoTIFF
- tcurv_threshold
- threshold tangential curvature
- Parameter format: float
- flowaccum_threshold
- threshold flow accumulation
- Parameter format: integer
- outputFormatType
- Format of output file
- Parameter format: string
- Options: GeoTIFF,TIFF,ESRI_Shapefile
- Default: GeoTIFF
- outputGeoTiffType
- Type of output GeoTIFF file if outputFormatType is specified as GeoTIFF
- Parameter format: string
- Options: Byte,Int16,UInt16,UInt32,Int32,Float32,Float64,CInt16,CInt32,CFloat32,CFloat64
- Default: Byte
Response Parameters:
returnURL
URL of output file to contain stream segments
returnFormat
Format of output file
See also
Luo, W. and T. F. Stepinski, 2008, “Identification of geologic contrasts from landscape dissection pattern: an application to Cascade Range, Oregon, USA”, Geomorphology, 10.1016/j.geomorph.2007.10.014, in press. See at http://www.niu.edu/landform/papers/GEOMOR_2483.pdf.
Molloy,B. I. and T.F. Stepinski, 2007, “Automated Mapping of Valley Networks on Mars“, Computers and Geoscience, 33, p728-738.
Tarboton, D.G., and D.P. Ames, 2001, “Advances in the mapping of flow networks from digital elevation data“, World Water and Environmental Resources Congress, ASCE, Orlando, Florida. See at http://hydrology.usu.edu/tardem/tardem4.0/.
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