X hits on this document

PDF document

Parameter Sensitivity in Hydrologic Modeling - page 18 / 163

449 views

0 shares

0 downloads

0 comments

18 / 163

when long records (greater than provides peak discharge estimates

25 years) are available. using annual peak stream

Statistical analysis flow data. Regional

regression commonly

equations based on used for calculating

the hydrologic parameters area flows at ungauged sites. These

and slope, are equations were

developed by the floods at ungauged

USGS in 1993 to estimate the magnitude and sites in six separate regions in Texas (Jennings et

frequency al., 1993).

of

2.3

EXTRACTING WATERSHED PARAMETERS FROM DIGITAL MODELS

Over the last twenty years, digital representations of topographic information have become increasingly available in the form of digital terrain models (DTMs). Using computers and extracting watershed data from digital terrain models is faster, and provides more reproducible measurements than traditional manual techniques using topographic maps (Garbrecht et al., 1999a).

GIS uses a DTM to describe the spatially distributed attributes of the terrain that are classified as topologic and topographic data. The topography of an area describes its elevation and land surface shape, while also important are the spatial distribution of terrain attributes other than elevation such as the land cover, soil type, and connectivity of the features. A DTM may be used to represent both topographic and/or physiographic features in the format of raster or grid data, triangulated irregular network (TIN) data or vector (point, line, and polygon) data (Olivera et al., 2000).

Using automated methods a surface may be analyzed so that drainage basin boundaries are defined, stream networks created, and drainage basin data

8

Document info
Document views449
Page views449
Page last viewedFri Dec 09 21:39:06 UTC 2016
Pages163
Paragraphs3546
Words25756

Comments