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Nam Won Kim, Yoo Seung Won, Jeongwoo Lee* , Jeong Eun Lee, Jaehak Jeong

Hydrologic Modeling of White Rock Creek Watershed with SWAT-

SWMM

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SWAT has been developed to evaluate impacts of various

Land use and land management conditions on water yield,

sediment and non-point source loadings.

Components : hydrology, weather, erosion, plant growth,

nutrients, pesticides, land management, stream routing.

SWAT is not able to treat urban drainage system.

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SWMM is capable of both single-event and continuous

simulation for runoff and water quality processes within

an urban catchment.

Routing process through a system of pipes, channels,

storage/treatment devices, pumps, and regulators can

be simulated.

SWMM has a difficulty in accounting for land cover types

other than urban.

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Comprehensive hydrological model is required to better

represent characteristics of both urban and rural areas.

SWAT-SWMM has been developed in order to overcome

the aforementioned shortcomings of SWAT and SWMM.

Main aims of the presentation

- To explain how to integrate SWAT and SWMM

- To illustrate some simulated results for the White Rock

Creek watershed in USA

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Initialize & Read

Start

Compute

Write

End

call getallo

..

.call headout

call simulate

call finalbalcall writeaacall pestw

S- 1

S- 3

S- 2

Initialize & Read

Start

Compute

Write

End

call getallo

..

.call headout

call simulate

call finalbalcall writeaacall pestw

S- 1

S- 3

S- 2

Initialize & Read

Start

Compute

Write

End

call RHYDRO01

call RHYDRO02

call HYDRO

call HCURVEcall PRPOLLcall PRFLOW

W- 1

W- 3

W- 2

Initialize & Read

Start

Compute

Write

End

call RHYDRO01

call RHYDRO02

call HYDRO

call HCURVEcall PRPOLLcall PRFLOW

W- 1

W- 3

W- 2

SWAT SWMM

embedded

Runoff

Transport

Extran

Storage Treatm

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HYDRO RDIIRES

GUTTER

WSHED

RDIISHED

QSHED

GUTTER

SMSTAT

RDIIRES

GUTTER

WSHED

RDIISHED

QSHED

GUTTER

SMSTAT

HYDRO

Com

puting

tim

e s

tep

Sim

ula

tion tim

e inte

rval of

SW

AT

W- 2- 1

W- 2- 2

W- 2- 3C

om

puting

tim

e s

tep

Com

puting

tim

e s

tep

HYDRO RDIIRES

GUTTER

WSHED

RDIISHED

QSHED

GUTTER

SMSTAT

RDIIRES

GUTTER

WSHED

RDIISHED

QSHED

GUTTER

SMSTAT

HYDRO

Com

puting

tim

e s

tep

Sim

ula

tion tim

e inte

rval of

SW

AT

W- 2- 1

W- 2- 2

W- 2- 3C

om

puting

tim

e s

tep

Com

puting

tim

e s

tep

subbasin.f

route.f

Separate “hydro” into land phase routing part and channel/pipe routing part

SWATSWMM

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Watershed

Sub-watershed

HRU

Catchment

Sub-catchment

SWAT SWMM

Channel Flow

Precip, Temp, PET

SurfQ, GwQ, EVT, SW

One subwatershed can be modelled by SWMM

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SWAT

SWAT

SWMM

Subcatchment = HRU

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SwatLandUseClassAGRRFRSDFRSEHAYRNGESWRNUIDUURHDURLDURMDWATRWETFWETN

“Dominant Land Use and Soil”“Multiple Land Use and Soil”

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SoilClassArentsAustinBurlesonDalcoEddyFerrisFrioHouston BlackLewisvillePitsStephenTrinityUrban landUstorthentsWater

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Denton

Dallas

Collins

outlet

Area : 172 km2

Altitude : El. 140-240 m

DEM : 30m x 30m

6 subwatersheds

Subwatershed No.1

= SWMM catchment

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SoilClassArentsAustinBurlesonDalcoEddyFerrisFrioHouston BlackLewisvillePitsStephenTrinityUrban landUstorthentsWater

SwatLandUseClassAGRRFRSDFRSEHAYRNGESWRNUIDUURHDURLDURMDWATRWETFWETN

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SWAT calibration was performed

for entire watershed

SWMM calibration was performed

for sub-watershed No1.

Major adjusted parameters

CN2 fo

EPCO fc

Ksat n

Gw_delay A1

FIMP A2

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0.01

0.10

1.00

10.00

100.00

1000.00

Feb-04 Apr-04 Jun-04 Aug-04 Oct-04 Dec-04 Feb-05 Apr-05 Jun-05

Date (month-year)

Dai

ly S

trea

m F

low

(m3 /s

)

ObservedSimulated

R2 = 0.91 Volume error < 5%

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0.01

0.10

1.00

10.00

100.00

1000.00

Nov-06 Jan-07 Mar-07 May-07 Jul-07 Sep-07 Nov-07 Jan-08

Date (month-year)

Dai

ly S

trea

m F

low

(m3 /s

)

ObservedSimulated R2 = 0.87 Volume error < 5%

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Outflow from SWAT

(=Inflow to SWMM)

Outflow from SWMM

(=Inflow to SWAT)

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y = 3.2961 x + 458.01R2 = 0.9877

0

200

400

600

800

1000

0 20 40 60 80 100

Imperviousness (%)

Annu

al w

ater

yie

ld (m

m)

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Variations of downstream flows at outlet

Variations of hydrological components

for the entire watershed

6 Cases of simulations were performed.

- Increase rate of impervious area

Current State, Case 1: 20 % , Case 2: 40 %

Case 3: 60 % , Case 4: 80 % , Case 5: 100 %

Increase of imperviousness

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0.0

20.0

40.0

60.0

80.0

100.0

Feb-04 Apr-04 Jun-04 Aug-04 Oct-04 Dec-04 Feb-05 Apr-05 Jun-05

Date (month-year)

Dai

ly S

trea

m F

low

(m3 /s

)

Current stateCase 5

37 %

25 %

(100 %)

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0.01

0.10

1.00

10.00

100.00

1000.00

Nov-06 Jan-07 Mar-07 May-07 Jul-07 Sep-07 Nov-07 Jan-08

Date (month-year)

Dai

ly S

trea

m F

low

(m3 /s

)

Current stateCase 5

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0

100

200

300

400

500

600

Surface flow Groundwater Percolation Evapotranspiraton Total yield

Hydrological components

Ann

ual a

vera

ge v

alue

s (m

m)

Current state 20% 40% 60% 80% 100%Increase rate of imperviousness

8 %

5 %

7 %15 %

5 %

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Performance of integrated SWAT-SMMM model was verified.

SWAT-SWMM can be effectively used for assessing hydrologic

components for urban as well as rural areas.

Future Works

- To link water quality components of SWAT and SWMM to

each other

- To make SWAT processes be calculated at subdaily time

scale

- To test applicability of SWAT-SWMM for other watersheds

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Thank you for listening !