This is a easy-to-learn material to guide how to formulate SWMM input file. After following, you will know how to simulate the hydrology of the study watershed. Also check the floodings of all nodes.

1. 0
Seoul National University of Science and Technology
Professor Eun-Sung Chung

2. 1

3. 2
Before
After
S1
S2
S3
S4
S5
S7
S6
O1
RainGage

4. 3
Date(M/D/Y) Time(H:M)
Start Analysis on 01/01/2007 00:00
Start Reporting on 01/01/2007 00:00
End Analysis on 01/01/2007 12:00
Start Sweeping on 01/01
End Sweeping on 12/31

5. 4
kt
cc effff 
 )( 0
f Infiltration rate at time (mm/h)
cf
0f
Constant infiltration rate after the soil has been saturated (mm/h)
Initial infiltration rate (mm/h)
k Decay constant specific to the soil (1/h)

6. 5

7. 6
Days Time(H:M:S)
Reporting 0 00:01:00
Runoff:
Dry Weather
0 01:00:00
Runoff:
Wet Weather
0 00:01:00
Routing 60 seconds

8. 7
 Connections
Subcatchment Outlet Junction
S1 J1
S2 J2
S3 J3
S4 J7
S5 J10
S6 J11
S7 J10
Conduit
Inlet
Node
Outlet
Node
C1 J1 J5
C2 J2 J11
C3 J3 J4
C4 J4 J5
C5 J5 J6
C6 J7 J6
C7 J6 J8
C8 J8 J9
C9 J9 J10
C10 J10 J11
C11 J11 O1

9. 8
Development Name
Rain
Gage
Total
Area
(ha)
Pcnt.
Imperv
(%)
Width
(m)
Pcnt.
Slope
(%)
Pre-
S1
Rain
gage
1500 0.0 460 2
S2 1600 3.0 490 2
S3 1500 5.0 430 2
Post-
S4 1000 56.8 700 3.1
S5 800 63.0 490 2
S6 700 87.7 210 3.1
S7 500 95.0 270 3.1
 Width = subcatchment area / length of the longest overland flow

10. 9
N-Imperv N-Perv
Dstore-
Imperv
Dstore-
Perv
%Zero-
Imperv
0.015 0.24 0.06 0.3 25
MaxRate MinRate Decay DryTime MaxInfil
4.5 0.2 6.5 7 0
 Subcatchment
 Infiltration method: Horton

11. 10
Parameter Description
N-Imperv Manning’s n for overland flow over the impervious portion of
the subcatchment
N-Perv Manning’s n for overland flow over the pervious portion of the
subcatchment
Dstore-
Imperv
Depth of depression storage on the impervious portion of the
subcatchment
Dstore-
perv
Depth of depression storage on the pervious portion of the
subcatchment
% Zero-
Imperv
Percent of the impervious area with no depression storage

12. 11
Length
(m)
Manning
N
Shape
Max.
Depth
(m)
Inlet
Offset
(m)
Initial Flow
(cms)
C1 50 0.05
CIRCLE
1 0 0
C2 50 0.016 1 0 0
C3 30 0.016 1 0 0
C4 40 0.05 1 0 0
C5 50 0.05 1 0 0
C6 40 0.05 1 0 0
C7 30 0.016 1 0 0
C8 50 0.05 1 0 0
C9 50 0.05 1 0 0
C10 40 0.05 1 0 0
C11 30 0.016 1 0 0

13. 12
click
Double click

14. 13
① General ② Dates ③ Time Steps
 Use given conditions to set-up the options

15. 14
 Define the flow unit
 Look at the left-bottom and select “CMS” for Flow Units

16. 15
Rain Gage
Subcatchment
Outfall
 Click the icon to create Rain Gage, Subcatchment, Outfall,
Junction, Conduit
Junction
Conduit

17. 16
 Add object toolbar at menu (in case of, cannot see toolbar)
1. Click ‘View’
2. Click ‘Object’ from ‘Toolbars’

18. 17
 Diagram of study area map
S1
S3
S2
S4
S5
S7
S6
O1
J1
J2
J3 J4 J5 J6
J7
J8 J9
J10
J11
C1
C3 C4 C5
C6
C7
C8
C9
C10
C11
C2
Subcatchment
Junction
Conduit
Outfall

19. 18
 Click the junction icon and click on the map to create
 Create 11 junctions as the following figure

20. 19
 Click the outfall icon and click on the map to create
 Create an outfall as the following figure

21. 20
1. 클릭
 Click the subcatchment icon and click on the map to create
 Left click to create the form, right click to complete creation
 Create 7 subcatchemnts

22. 21
 Click the conduit icon
 Click inlet junction for the starting point and outlet junction for
the ending point
 Create 11 conduits
1. click inlet junction
2. click outlet junction

23. 22
1. 클릭
 Change names of subcatchments, junctions,
and conduits
 Open properties of subcatchment
 Enter the name of outlet
Subcatchment S1 is
connected to junction J1

24. 23

25. 24
click
click
Insert rainfall data
enter name

26. 25
Time Rainfall
0:00:00 0.29
0:05:00 0.33
0:10:00 0.38
0:15:00 0.64
0:20:00 0.81
0:25:00 1.57
0:30:00 20.85
0:35:00 15.18
0:40:00 0.71
0:45:00 0.42
0:50:00 0.35
0:55:00 0.3
1:00:00 0.2
1:05:00 0.19
1:10:00 0.18
1:15:00 0.17
1:20:00 0.17
1:25:00 0.16
1:30:00 0.15
1:35:00 0.15
1:40:00 0.14
1:45:00 0.14
1:50:00 0.13
1:55:00 0.13
Insert rainfall data

27. 26
② Outfall① Rain Gage
 Insert values below
 Select time-series for rain gage
 Outfall Invert EL. : 509 m

28. 27
③ Subcatchment
1. Insert given values for each subcatchment
2. Insert values for infiltration
3. Connect junction(outlet)s and raingage for all
subcatchments
클릭
2.
3.

29. 28
④ Junction 1. Insert values
Junction
Invert EL.
(m)
J1 520
J2 515
J3 518
J4 517
J5 516
J6 515
J7 516
J8 514
J9 513
J10 512
J11 511

30. 29
⑤ Conduit
1. Insert given values
2. Select shape of conduit & insert values
3. Check the in/outlet nodes are connected correctly
2.
click
3.

31. 30
Click run

32. 31
click Check the flow between junctions
 select a node element from the map
then click +
Check profile plot

33. 32
click
1. Select start/end date
2. Select object and variable for x axile
3. Select object and variable for y axile
Check result
1.
2. 3.

34. 33
click
Check results
1.
2.
3. 4.
1. Select start/end date
2. Select time format and objects
3. Select variables
4. Select an element from map then click +

35. 34
click
1. Select start/end date
2. Select time format and objects
3. Select variables
4. Select an element from map then click +
Check results
1.
2.
3.
4.

36. 35
T= 12 mins T= 54 mins
T= 2hr 14mins T= 6hrs 3mins

37. 36
 Check the result of Flooding: J8, J9 and J10

38. 37
 Check the graph of Total flow and Depth (J11)
 Change the format of lines, axes and legends

39. 38
 Check the summary results
 Find all flooded pipes

40. 39
 Insert the values for Outlet Offset as given table below
Length
(m)
Manning
N
Shape
Max.
Depth
(m)
Inlet
Offset
(m)
Initial
Flow
(cms)
Outlet
Offset
(m)
C1 50 0.05
CIRCLE
1 0 0 0
C2 50 0.016 1 0 0 0.5
C3 30 0.016 1 0 0 0
C4 40 0.05 1 0 0 0
C5 50 0.05 1 0 0 0.5
C6 40 0.05 1 0 0 0
C7 30 0.016 1 0 0 0
C8 50 0.05 1 0 0 0
C9 50 0.05 1 0 0 0.5
C10 40 0.05 1 0 0 0
C11 30 0.016 1 0 0 0

41. 40
5. Check the flooding

42. 41
 Change the diameter of conduits C8 and C9 as given
table below
Conduit
Length
(m)
Manning
N
Shape
Max.
Depth
(m)
Inlet
Offset
(m)
Initial
Flow
(cms)
Outlet
Offset
(m)
C1 50 0.05
CIRCLE
1 0 0 0
C2 50 0.016 1 0 0 0.5
C3 30 0.016 1 0 0 0
C4 40 0.05 1 0 0 0
C5 50 0.05 1 0 0 0.5
C6 40 0.05 1 0 0 0
C7 30 0.016 1 0 0 0
C8 50 0.05 1.3 0 0 0
C9 50 0.05 1.3 0 0 0.5
C10 40 0.05 1 0 0 0
C11 30 0.016 1 0 0 0

43. 42
Check the difference

44. 43
43
 Checking results of flooding
• When flooding occurs after the SWMM run, there will be a
difference in flooding loss in the status result

45. 44
1. What is the maximum flow depth for all nodes. Use the
changed outlet offsets for C2, C5 and C9 and the previous
diameters, 1.0 m for C8 and C9.
2. What is the minimum diameter for C8 and C9 without
flooding at J8 and J9? A flooding at C10 still exists.
3. What is the maximum elevation of J11 without flooding at
J10? Use the found diameters of C8 and C9 from Problem 2.
4. Draw a graph including hydrograph and flow depth time
series at the outfall.
5. Find the exact peak time and peak runoff at the outfall.