DES 606 Watershed Hydrology using HEC-HMS
25 Jul 2011
DES 606 Exercise 13 Build an HEC-HMS Model with Multiple Sub-Basins
Purpose
Reinforce training regarding watershed modeling in HMS for multiple sub-basin
watersheds.
Requirements
1) Adobe Acrobat Pro (for measuring).
2) HEC-HMS
2) MS Image Viewer (should be standard with Windows) to manipulate an image.
3) A calculator (or Excel)
Problem Statement
Figure 1 is an image of a watershed – we will assume in Texas somewhere.
Figure 1. Four-Basin Training Watershed
Table 1 lists properties of the watersheds depicted in the Figure.
Table 1. Watershed Properties
ID
1
2
3
4
Area
1.52
2.17
0.96
0.86
MCL
(mi)
2.65
1.85
1.13
1.49
Slope
0.009
0.01
0.008
0.011
CN
D
70
84
80
70
R
0
0
0
0
Using the methods presented perform the following modeling exercises:
Exercise 13
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1
1
1
1
DES 606 Watershed Hydrology using HEC-HMS
25 Jul 2011
1) Use SIR 2007-5243 to estimate the Lag time for each sub-watershed. Put the
result in the table below. The SIR estimates time of peak, how is this time related
to lag time?
ID
1
2
3
4
Area
(sq.mi)
1.52
2.17
0.96
0.86
MCL
(mi)
2.65
1.85
1.13
1.49
Lag
(hrs)
K
1.4
1.0
0.9
0.8
4.1
3.9
3.7
3.8
SCSOK?
Yes
Yes
Yes
Yes
2) Flow from Area 4 and Area 2 to the outlet are to be modeled using the
Muskingum procedure. An independent analysis determined that K= 0.3 hr for
the reach through Area 3 and x=0.2; K=0.6 hr for the reach through Area 1 and
x=0.02.
3) Sketch a conceptual model to help you build the HMS model
Exercise 13
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DES 606 Watershed Hydrology using HEC-HMS
25 Jul 2011
4) Use an SCS Type-1 storm model as the input hyetograph. The total depth is 10
inches, and the storm is a 1% chance storm (100-yr).
5) Produce a runoff hydrograph at the outlet - save this hydrograph to a runoff gage
and name the gage the base gage.
Exercise 13
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