WMS:OC Unit Hydro Unit Hydrograph Method: Difference between revisions

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A lag time and S-graph are required to compute a unit hydrograph. Compute a unit hydrograph for a basin by first selecting the basin and then choosing the '''Unit Hydrograph Method...''' button from the [[WMS:Orange County Unit Hydrograph|Edit Orange County Unit Hydrograph Parameters]] dialog.
[[File:OC UnitHydrograph.png|thumb|400 px|Orange County Unit Hydrograph]]
A lag time and S-graph are required to compute a unit hydrograph. Compute a unit hydrograph for a basin by first selecting the basin and then choosing the '''Unit Hydrograph Method...''' button from the [[WMS:Orange County Unit Hydrograph|''Edit Orange County Unit Hydrograph Parameters'']] dialog.


==Lag Time==
==Lag Time==
Basin lag time (hrs) is usually based on the time of concentration (<math>T_c</math>) computed using the rational method analysis. Lag time is automatically calculated to be <math>0.8*T_c</math> when you enter a value for <math>T_c</math>, but you can always enter any value for lag time. Entering a <math>T_c</math> value is not required because it is only used to compute lag time.
Basin lag time (hrs) is usually based on the time of concentration (''T<sub>c</sub>'') computed using the rational method analysis. Lag time is automatically calculated to be ''0.8*T<sub>c</sub>'' when entering a value for ''T<sub>c</sub>'', but it is always possible to enter any value for lag time. Entering a ''T<sub>c</sub>'' value is not required because it is only used to compute lag time.


==S-graphs==
==S-graphs==
There are four standard S-graphs that are used in Orange County: valley developed, valley undeveloped, foothill, and mountain. The user must toggle the check box on next to each S-graph that is to be used. A composite S-graph is computed using the decimal weights assigned to each of the standard S-graphs.
There are four standard S-graphs that are used in Orange County: valley developed, valley undeveloped, foothill, and mountain. Turn on the check box on next to each S-graph that is to be used. A composite S-graph is computed using the decimal weights assigned to each of the standard S-graphs.


The '''Plot Unit Hydrograph''' button computes the unit hydrograph using the lag time and composite S-graph and displays the results in both a graphical and tabular format.
The '''Plot Unit Hydrograph''' button computes the unit hydrograph using the lag time and composite S-graph and displays the results in both a graphical and tabular format.
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==Related Topics==
==Related Topics==
* [[WMS:Basin HEC-1 Cards#Derived Unit Hydrograph (UI)|Derived Unit Hydrograph]]
* [[WMS:Basin HEC-1 Cards#Derived Unit Hydrograph (UI)|Derived Unit Hydrograph]]
* [[WMS:OC Rational Reports|Tc from Rational Method]]
* [[WMS:Orange_County_Rational_Method#Reports|Tc from Rational Method]]




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[[Category:OC Unit Hydrograph|U]]
[[Category:OC Unit Hydrograph|U]]
[[Category:Equations|OC Unit Hydro]]
[[Category:WMS Plot]]
[[Category:OC Unit Dialogs|uni]]

Latest revision as of 16:18, 7 December 2017

Orange County Unit Hydrograph

A lag time and S-graph are required to compute a unit hydrograph. Compute a unit hydrograph for a basin by first selecting the basin and then choosing the Unit Hydrograph Method... button from the Edit Orange County Unit Hydrograph Parameters dialog.

Lag Time

Basin lag time (hrs) is usually based on the time of concentration (Tc) computed using the rational method analysis. Lag time is automatically calculated to be 0.8*Tc when entering a value for Tc, but it is always possible to enter any value for lag time. Entering a Tc value is not required because it is only used to compute lag time.

S-graphs

There are four standard S-graphs that are used in Orange County: valley developed, valley undeveloped, foothill, and mountain. Turn on the check box on next to each S-graph that is to be used. A composite S-graph is computed using the decimal weights assigned to each of the standard S-graphs.

The Plot Unit Hydrograph button computes the unit hydrograph using the lag time and composite S-graph and displays the results in both a graphical and tabular format.

Clicking on OK will write the unit hydrograph data to the UI card for analysis using HEC-1.

Related Topics