WMS:Travel Times from Basin Data

WMS computes many geometric parameters when using the Compute Basin Data command for either a TIN or DEM. These parameters form the basis of the empirical equations used to compute lag time and time of concentration. The Basin Time Computation dialog allows you to select from a series of pre-defined equations (Dodson & Associates, 1992), or create your own equation using any of computed basin parameters to compute time of concentration or lag time. If the equation is a function of variable not computed by WMS then you will have to enter the value in this dialog before a travel time can be computed. The process of computing travel times for a selected basin from computed basin data involves the following two steps:

1. Select an equation (or create a new one).
2. Follow the instructions provided in the Instructions / Results text window until all of the necessary data are correctly defined (you may also edit any of the variables computed by WMS).

Auto Recomputing

By default once an equation is specified for a basin, the lag time and time of concentration will be computed automatically each time that basin data are computed or when the curve number changes. If you do not wish to have the equation updated when basin data changes then you should turn on the Do not Auto-recompute parameters check box for the selected basin.

Related Topics

• Assigning Equations to a Basin
• Updating a travel time when basin parameters change
• Customizing Equations
• Exporting Results
• Geometric Parameters Used by Equations
• Travel Times from Map Data