Maximum manning's n coefficient( overland flow)

[phuong nguyen]

Dear SWAT user,

 I am calibrating result  with OV_N and some coefficients. But  in my  case manning of OV_N too hight  (2-3) when I finished  ( I mean NS=0.72 and R2=0.8).

I  worry It out range. ( I see in MWSWAT2012 range of OV_N : 0.01-30 ? )

I hope to received your advices

Thank you so much.

Best,

Phuong

[Jim Almendinger]

Most Manning's n values are much less than 1 (one).  Table 5.4 in Ward and Trimble (1995.  Environmental Hydrology, 2nd ed.) gives an n value of 0.8 for dense underbrush, which is the largest value in their table.  Grasslands range from 0.15 to 0.41; grassed waterways 0.025-0.035.  (I don't know why the grassed waterway would be so much less than grasslands...) 

Just FYI,

-- Jim

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From: "phuong nguyen" <phuon...@gmail.com>
To: swat...@googlegroups.com
Sent: Tuesday, October 14, 2014 4:19:44 AM
Subject: [SWAT-user:5051] Maximum manning's n coefficient( overland flow)

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Dr. James E. Almendinger
St. Croix Watershed Research Station
Science Museum of Minnesota
16910 152nd St N
Marine on St. Croix, MN  55047
tel: 651-433-5953 ext 19

[phuong nguyen]

Dear Dr James,

Thank for your advices. I think  this result  isn't common.

Now, I try to find solution for this (change  Surlag and slopes, reduced OV_N ) , but I still get bad result.

Best,

[Andrey Bugaets]

its would be right value for mountains soils filled (70-90%) with stones and rock fragments make underflow conduits.

вторник, 14 октября 2014 г., 20:19:44 UTC+11 пользователь phuong nguyen написал: