WMS:Variables Computed by WMS
A complete list of variables computed for drainage basins that are available for use in defining equations, along with the acronyms used in WMS is given below:
- A = The area of the basin in the units specified prior to computing basin parameters.
- BS = The average basin slope, or average slope of the triangles or cells comprising this basin. A triangle or cell's slope is computed as the change in elevation divided by the change in XY or plan distance.
- AOFD = The average overland flow distance within the basin. This is computed by averaging the overland distance traveled from the centroid of each triangle to the nearest stream.
- %NF = The percentage of the basin whose aspect is directed North where North is defined as the positive Y direction.
- %SF = The percentage of the basin whose aspect is directed South where South is defined as the negative Y direction.
- L = The basin length.
- P = The perimeter of the basin.
- Shape = The shape factor of the basin, or the length divided by the width.
- Sin = The sinuosity factor of the stream in the basin. Defined by dividing the maximum stream length in the basin by the length.
- AVEL = The mean basin elevation.
- MFD = The maximum flow distance within a basin including both overland and channel flow.
- MFDS = The slope of the MFD.
- CTOMFD = The distance from the centroid of the basin to the nearest point associated with the MFD.
- CSD = The distance from the centroid of the basin to a point in the stream which is a part of the MFD. The CSD differs from the CTOMFD in that it is only concerned with the channel or stream flow portion of the MFD, whereas the CTOMFD also incorporates the portion of the MFD which is overland flow.
- CSS = The slope of the CSD.
- MSL = The maximum stream length within the basin. This is computed by determining the maximum distance traveled when "flowing" down from the top of streams in a basin and where the streams exit the basin.
- MSS = The slope of the MSL.
In addition to the basin attributes defined above the following stream attributes are computed:
- L = Stream lengths for each segment.
- SS = Stream slopes for each segment.
WMS – Watershed Modeling System
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