WMS:Putnam Lag Time Equation: Difference between revisions

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Putnam (1972) developed a lag equation for watersheds around the Wichita, Kansas area as follows:
Putnam (1972) developed a lag equation for watersheds around the Wichita, Kansas area as follows:


:[[Image:image118.gif]]
:<math>T_{LAG} = 0.49 \sqrt { \frac {L}{ \sqrt {S}}} I_a^{-0.57}</math>


where:
where:


<math>T_{LAG}</math> = lag time in hours.
:''T<sub>LAG</sub>'' = lag time in hours.


<math>L</math> = maximum flow length in miles.
:''L'' = maximum flow length in miles.


<math>S</math> = weighted slope along the maximum flow path in ft/mile.
:''S'' = weighted slope along the maximum flow path in ft/mile.


<math>I_a</math> = Impervious cover as a fraction.
:''I<sub>a</sub>'' = Impervious cover as a fraction.


This equation was used for watersheds ranging in size from 0.3 to 150 sq. miles, impervious covers less than 0.3 and a ratio of  between 1.0 and 9.0.
This equation was used for watersheds ranging in size from 0.3 to 150 sq. miles, impervious covers less than 0.3 and a ratio of  between 1.0 and 9.0.
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[[Category:Equations|Putnam]]
[[Category:WMS Basins|Putnam]]
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Latest revision as of 15:13, 29 September 2017

Putnam (1972) developed a lag equation for watersheds around the Wichita, Kansas area as follows:

where:

TLAG = lag time in hours.
L = maximum flow length in miles.
S = weighted slope along the maximum flow path in ft/mile.
Ia = Impervious cover as a fraction.

This equation was used for watersheds ranging in size from 0.3 to 150 sq. miles, impervious covers less than 0.3 and a ratio of between 1.0 and 9.0.


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