WMS:Overview of Basin Data Equations

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Dodson (Dodson & Associates, 1992) compiled several equations from hydrologic publications. WMS has implemented many of these equations and allows choosing from the ones listed below to automatically compute lag times/times of concentration. Because most of the equations were developed for specific watersheds (e.g. size, land cover etc.), consider the assumptions made about a given equation, and try to identify one that used watershed conditions similar to the one being studied. The following is a list of the equations available in WMS. The SCS also found that for many cases the lag time could be related to the concentration time by the following equation:

T_{LAG} = 0.6 \ast T_c

This relationship is always used by WMS to determine lag time when a method for computing time of concentration is chosen, or to compute time of concentration when a method for lag time is chosen. Methods used for lag time begin with TLAG = whereas methods used to compute time of concentration begin with tc =.

Lag Time Based Equations:

Colorado State
Riverside County
Taylor Schwartz
Tulsa District

Time of Concentration Based Equations:

Fort Bend

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