swmm presentation

5/26/2018 SWMM Presentation

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Parameter optimization of SWMM for Runoff

Quantity and Quality Calculation in a Eutrophic

Lake Watershed Using a Genetic Algorithm

Presented by :Oktarian Wisnu Lusantono

14143701


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In the recent years, several lagoons in the eastcoast area of Korea polluted by diffuse pollutant

Purpose of this study is for improving Youngrang

Lake water quality, thus it is necessary estimatethe diffuse pollution load from it watershed

This study using SWMM (Huber andDickinson,1988; Tsihrintzis and Hamid,1998)

integrated with genetic algorithm (GA)(Goldberg,1989; Gen and Cheng,1997; Cho etal.,2004)

Background


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SWMM has various blocks, in this studyrunoff block was used to calculate the runoffflow and diffuse pollution loads in Jangcheon

watershed Transport block in SWMM was used to

calculate the transport of runoff flow anddiffuse pollution loads in the channel

Calibration for SWMM using manual andautomatic integrated with GA for optimizingSWMM parameters.

Methods


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Study Flowchart- Parameters setting for the genetic operation

- Observed runoff quantity and quality data input- Generate random individuals of the initial generation

- Parents selection according to the fitness

- Offsprings production by crossover and mutation

- Runoff quantity and quality calculation using SWMM- Evaluation of fitness level by SSQ from observed and calculated values

Complete of a new

generation

The new generation

satisfies termination

criteria?

Determination of optimum parameters of SWMM

Yes

Yes

No

No


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Data

Figure 1. The Yeongrang Lake Watershed (4.7 km2)

Remarks :

Arable land 16.5%

Forest 67.7%

Residental area 3.1%

Residental area 12.6%


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Rainfall Event Date Precipitation (mm) Duration (hr) Dry day prior to storm

05 1 June 30 19.6 5 3.2

05 2 July 8 46 18 3.2

05 3 July 28 29 12.5 14.7

05 4 August 24 96.2 28.2 2.8

Table 1. Surveyed Rainfall Events (2005)

Figure 2. Subcathcments and Channel Network for SWMM


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Result and Discussion

Parameters Ranges

Impervious area Mannings roughness 0.001 ~ 0.013

Pervious area Mannings roughness 0.13 ~ 0.51

Max infiltration rate 87.1 ~ 162.0 mm/hr

Min infiltration rate 3.2 ~ 17.8 mm/hr

Impervious depression storage 0.19 ~ 0.72 mm

Pervious depression storage 0.50 ~ 1.49 mm

Channel roughness coefficient 0.11 ~ 0.2Buildup exponent 0.13 ~ 1.11

Buildup coefficient 0.001 ~ 7.71

Washoff exponent 0.16 ~ 9.83

Washoff coefficient 1.0 ~ 19.6

Table 2. Ranges of SWMM Parameters Determined from GA and SWMM


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Month Diffuse pollution loads (kg/year)BOD (kg) COD (kg) SS (kg) TP (kg)

January 910 3885 33847 23.7

February 582 3416 7018 18.5

March 552 3282 2181 16.6

April 674 3883 13472 23.8

May 850 4318 23269 30.0

June 1117 4657 47015 32.9

Juli 2060 11937 170673 151.6

August 2467 14012 267134 199.3

September 2440 9166 225621 101.8

October 871 4424 42524 29.0

November 932 4085 45640 29.2

December 636 3675 6952 20.9

Total 1.41 x 104 7.07 x 104 8.85 x 105 6.78 x 102

Table 3. Monthly Average Pollution Loads Discharged from the Jangcheon Watershed


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SubcatchmentDiffuse pollution loads (kg/year)

BOD (kg) COD (kg) SS (kg) TP (kg)

1 1.47 x 103 6.73 x 103 9.62 x 103 3.85 x 101

2 2.76 x 103 1.35 x 104 5.29 x 104 1.31x 102

3 2.95 x 103 1.46 x 104 3.99 x 104 1.76 x 102

4 1.84 x 103 7.84 x 104 4.67 x 104 7.12 x 101

5 1.79x 103 1.24 x 104 1.44 x 104 1.24 x 102

6 3.29x 103 1.57 x 104 2.33 x 104 1.37 x 102

Total 1.41 x 104 7.07 x 104 8.85 x 105 6.78 x 102

Table 4. Yearly Average Pollution Loads at Each Subcatchment


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Figure 3. Calibration Result of runoff flow using GA

Figure 4. Calibration Result of BOD using GA


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Figure 5. Calibration Result of COD using GA

Figure 6. Calibration Result of SS using GA


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Figure 7. Calibration Result of TP using GA


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Automatic calibration method for SWMMwas applied in the Jangcheon of YoungrangLake Watershed, the calibration using GA

From SWMM continuous simulation over 5years, pollution loads in the summer seasonconsiderably larger than the other seasons.

Residential and agricultural area estimatedhave pollution loads larger than the othersub-catchments area

Conclusion


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Thank you

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