Chapter 8 Modeling Channel Flow with HEC-HMS

estimated, but the estimates can be verified only with observed flows. Thus these empirical models should be avoided if the watershed and channel are ungaged.

Table 8-3 summarizes the model selection criteria.

Table 8-3. Guidelines for selecting routing model

If this is true ...

No observed hydrograph data available for calibration

Significant backwater will influence discharge hydrograph

Flood wave will go out of bank, into floodplain

TS u Channel slope> 0.002 and _0_0 :?: 171 do

Channel slopes from 0.002 to 0.0004 and TSouo :?: 171

do

Channel slope < 0.0004 and

( )1/2

TSo ~ ~30

Channel slope < 0.0004 and

TSo(~r2