Presentation

2010 International SWAT Conference

Chul-gyum Kim*, Nam-won Kim*, Seung-woo Park**

*Korea Institute of Construction Technology, Ilsan, Korea **Seoul National University, Seoul, Korea Contents

• Background & Objectives

• SWAT model application

• Estimation of transmission characteristics

• Assessing impact of sediment & nutrient export

• Conclusions Background

• The total Maximum Daily Load(TMDL) program has been performed for the Geum River, Yeongsan River, Seomjin River, and some areas of the Han River of Korea since August of 2004 starting on the Nakdong River basin.

• TMDLs are quantitative objectives and strategies needed to achieve water quality standards, which can be implemented by controlling the discharged loads from the upstream areas.

• To decide the way and the amount of discharged loads to be reduced, it is necessary to accurately estimate the impact of the loads from the upstream areas on the water quality standards at the downstream point of interest. Objectives are

• Simulating the discharged pollutants to stream reaches such as sediment, nitrogen, and phosphorus

• Quantitatively estimating how much the pollutants are delivered to the downstream point of interest and actually contribute the total loads at the Chungju Dam Pollutant transport in a watershed

①

a’ ①’ ② A’ ②’

B Pollutant transport in SWAT

Surface flow, lateral flow, groundwater flow, sediment Subbasin 1 yield, nutrient yield, … Point source Main channel routing Reach 1 - Flow : Muskingum - Sediment : degradation or deposition by transport capacity - Nutrients : QUAL2E algorithm Subbasin 2 A ① Point source a Reach 2

a’ ①’ Subbasin 3 ② A’ ②’

B Transmission ratio

Transmission loss (USDA NRCS, 2001) “A reduction in volume of flow in a stream, canal, or other waterway, due to infiltration or seepage into the channel bed and banks.” focused on decrease of water volume

extend to the sediment and pollutants Definition of “Transmission Ratio”

 the ratio of the delivered load to a downstream reach to the discharged load into a upstream reach

 a decrease or an increase of sediment and pollutant loads by degradation or deposition, and in-stream nutrient transport processes through streams

TR = f (Loadin , QUAL2E reaction coefficients, ...)

Rainfall-Runoff processes Methodological approach

SWATSWAT--KK setset--upup Climate data (Rainfall, Temperature, …) forfor thethe ChungjuChungjuDamDam watershedwatershed GIS data (DEM, Landuse, Soil, …)

Pollutant source

Point Nonpoint (Population/Industry/Livestock) (Landuse)

reduction

Treatment facilities

NonpointNonpoint PointPoint dischargeddischarged loadload dischargeddischarged loadload byby SWATSWAT

Transmission stream routing & in-stream process ratio

{ calibration & validation Measured data of Delivered load the Ministry of Environment

Analyzing transmission characteristics

Contribution assessment of pollutant export Reach 1

Subbasin 1 Load S1 Subbasin 1

TRR1 Reach 1 Reach 2 Subbasin 2

Subbasin 2 LoadS 2

TRR2 Reach 2 Main outlet

Dam.Load = Load ×TR ×TR ×... Subbasin 3 S1_in S1 R1 R2

Chungju Dam Chungju Dam watershed

Drainage area : 6,648 km2

Odae- cheon

Pyeongchang- gang

Golji- cheon Ju-cheon

Jecheon- cheon Okdong- cheon

Chungju Reservoir

Weather station (KMA) TMDL outlet (MOE)

0 10 20 30 40 km Sub-watershed & reach

The watershed is divided to 11 sub-watersheds where the hydrologic or water quality data is Odae A S1 S2 Golji A monitored R1 R2

Pyeongchanggang S5 Yeongweol S4 R5 R4 Hangang A R3 R6 R7 S3 S6 S8 S7

Jucheon A Pyeongchang A Okdong A R8

Sub-watershed S11 Hangang B Reach R11 Jecheon A R9 S9 S10 Chungju Dam

R10 Model input : weather data

Five stations : Daegwallyeong, Wonju, Yeongwol, Chungju, Jecheon Odae- cheon Daily data Pyeongchang- gang - Rainfall Golji- cheon Ju-cheon - Max. & Min. Temperature - Wind Velocity - Relative Humidity Jecheon- cheon Okdong- - Solar Radiation cheon

Chungju Reservoir

Weather station (KMA) TMDL outlet (MOE)

0 10 20 30 40 km Model input : DEM

30 m DEM from NGIS digital map (1/5,000)

Model input : soil

Detailed soil map (1/25,000) of NAAS (National Academy of Agricultural Science)  128 soil groups

Soil Class

0 10 20 30 40 km Model input : landuse

Level-2 landcover map of MOE (Ministry of Environment)  Forest 83%, Upland 10%, Paddy 3%

Landuse Class

0 10 20 30 40 km Point source

4.5 Sediment 4.0 Total nitrogen 3.5 Total phosphorus

3.0

2.5

2.0

1.5

Point load (1,000 kg/day) 1.0

0.5

0.0 S1 S2 S3 S4 S5 S6 S7 S8 S9 S10 S11 Sub-watershed Calibration & validation

Flow Sediment Nutrients

SOL_NO3 GW_DELAY CH_EROD FRT_LY1 ALPHA_BF CH_COV RSDCO GWQMN ADJ_PKR NPERCO SLSOIL PRF AI1 SOL_ORGN ESCO SPCON SOL_MINP SPEXP PPERCO Statistical Criteria PHOSKD coefficient of determination (R2) AI2 mean absolute error (MAE) SOL_ORGP relative mean absolute error (RMAE) Nash-Sutcliffe model efficiency (ME) 7-day window statistical criteria % of observed values within 7-day MIN~MAX range % of observed values > 7-day MAX % of observed values < 7-day MIN Average & Median Calibration – flow

20000 0

100 Inflow at the Chungju Dam Precipitation for the period 2005~2009 200 15000 Observed flow Simulated flow 300 Precipitation (mm) /sec)

3 400

10000 500

1000000 100000 100000600 2 2

Daily flow (m R = 0.73 R = 0.95 700 Observed ME= 0.72 ME= 0.91 5000 Simulated 10000 800 /sec) 3

/sec) 10000

3 900 1000 10000 0 1000 /sec)

Jan-05 Jul-05 Jan-06 3 Jul-06 Jan-07 Jul-07 100 100

10 1000 1 Daily flow (m

Simulated daily flow (m 1 Simulated monthly flow (m flow monthly Simulated

0.1 0.01 100 0.01 1 100 10000 1000000 100 1000 10000 100000 0.01 3 3 Observed daily flow (m /sec) Observed monthly flow (m /sec) 0 10 20 30 40 50 60 70 80 90 100 Exceedance frequency (%) Validation – flow

100000 0 Jucheon station 100 10000 1000 R2 = 0.67 200 ME= 0.66 1000 300

100 /sec) /sec) 3 3 400 Precipitation (mm) 100 500 10 10 600

Streamflow (m 1 700 1 Simulated daily flow (m 800 0.1 Observed 900 0.1 Simulated 0.1 1 10 100 1000 3 0.01 1000 Observed daily flow (m /sec) Apr-07 May-07 Jun-07 Jul-07 Aug-07 Sep-07 Oct-07

Yeongchun station 100000 0 100 10000 10000 R2 = 0.77 200 ME= 0.76 1000 300

1000 /sec) /sec) 3 3 400 Precipitation (mm) 100 500 100 10 600

Streamflow (m 1 700 10 Simulated daily flow (m 800 0.1 Observed 900 1 Simulated 1 10 100 1000 10000 0.01 1000 Observed daily flow (m3/sec) Apr-06 May-06 Jun-06 Jul-06 Aug-06 Sep-06 Oct-06 Calibration – sediment

Observed and simulated daily sediment loads at the Hangang A

100000

10000

1000

100

Sediment load (t/day) load Sediment 1

0.1 Simulated Observed 0.01 Jan-07 May-07 Sep-07 Jan-08 May-08 Sep-08 Jan-09 May-09 Sep-09 Validation – sediment

Golji A (S2)

10000

1000

100

Sediment load (t/day) load Sediment 0.1

0.01 Simulated Observed Pyeongchang A (S6) 0.001 Jan-07 May-07 Sep-07 Jan-08 May-08 Sep-08 Jan-09 May-09 Sep-09 10000

1000

100

Sediment load (t/day) load Sediment 0.1

0.01 Simulated Observed 0.001 Jan-07 May-07 Sep-07 Jan-08 May-08 Sep-08 Jan-09 May-09 Sep-09 Calibration – nutrients (N, P)

Observed and simulated daily nutrient loads at the Hangang A

1000

100

10 T-N load (t/day) load T-N

Simulated Observed 0.1 100 Jan-07 May-07 Sep-07 Jan-08 May-08 Sep-08 Jan-09 May-09 Sep-09

0.1

T-P load (t/day) load T-P 0.01

0.001 Simulated Observed 0.0001 Jan-07 May-07 Sep-07 Jan-08 May-08 Sep-08 Jan-09 May-09 Sep-09 Validation – nutrients (N, P)

Golji A (S2) Pyeongchang A (S6)

1000 1000 Simulated Observed 100 100

10 10

1 1 T-N load (t/day) load T-N T-N load (t/day) load T-N

0.1 0.1 Simulated Observed 0.01 0.01 Jan-07 May-07 Sep-07 Jan-08 May-08 Sep-08 Jan-09 May-09 Sep-09 Jan-07 May-07 Sep-07 Jan-08 May-08 Sep-08 Jan-09 May-09 Sep-09

100 100 Simulated Observed 10 10

1 1

0.1 0.1

0.01 0.01 T-P load (t/day) T-P load T-P load (t/day) load T-P 0.001 0.001

0.0001 0.0001 Simulated Observed 0.00001 0.00001 Jan-07 May-07 Sep-07 Jan-08 May-08 Sep-08 Jan-09 May-09 Sep-09 Jan-07 May-07 Sep-07 Jan-08 May-08 Sep-08 Jan-09 May-09 Sep-09 Calculation of transmission ratio

TL Delivered load at the downstream point TR = out TLin Point discharged load + Nonpoint discharged load (+ Upstream load)

Estimating pollutant transmission ratios from the model results for the period 1980~2009 for various meteorological conditions TLin

TLout Transmission ratio by rainfall amounts

100000 at the Golji A 10000

1000

100

10 13%

0.1

Sediment transmission ratio transmission (%) Sediment 0 100 200 300 400 500 600 700 800 900 Rainfall (mm) 1000

100 93%

10 T-N transmission ratioT-N transmission (%) 0 100 200 300 400 500 600 700 800 900 Rainfall (mm)

1000

100 87%

10 T-P transmission ratio transmission (%) T-P 0 100 200 300 400 500 600 700 800 900 Rainfall (mm) Fraction of pollutant loads by rainfall amounts at the Golji A

Below 130 mm Above 28% 130 mm 72%

Sediment

Below Below Above 130 mm Above 130 mm 130 mm 21% 130 mm 44% 56% 79%

T-N T-P Transmission ratio for flow durations at the Golji A

High flow Low flow 120 T-N T-P Sediment

100

40 Transmission ratio (%)

0 > Q95 Q95~Q185 Q185~Q275 Q275~Q355 < Q355 Flow duration Fraction of pollutant loads for flow durations

Ⅲ at the Golji A Ⅳ Ⅱ 0% 1% 0%

Ⅴ 0%

Sediment Ⅲ Ⅳ Ⅲ Ⅱ Ⅰ Ⅱ Ⅳ 4% 1% 0% 11% 99% 2% 0%

Ⅴ Ⅴ 0% 0%

T-N Ⅰ T-P Ⅰ 84% 98%

* Ⅰ: > Q95, Ⅱ: Q95~Q185, Ⅲ: Q185~Q275, Ⅳ: Q275~Q355, Ⅴ: < Q355 Total TR for sub-watersheds

120 T-N T-P Sediment Total TR from each sub-watershed to 100 the Chungju Dam

60 TRtotal = ∏TR(i) 40 i Transmission ratio (%) ratio Transmission

0 100 R1 R2 R3 R4 R5 R6 R7 R8 R9 R11 T-N T-P Sediment Reach 80

• Total TR of downstream sub-watersheds is 60 higher than one of upstream areas

 Application of BMPs to reduce pollutant 40 export into the stream waterbodies near the mouth of the watershed would be more 20 effective than application of the same ones Total TR of each sub-watershed (%) on upstream areas near the head of the watershed 0 S1 S2 S3 S4 S5 S6 S7 S8 S9 S11 Sub-watershed Contribution of point & nonpoint pollutants

Fraction of point and nonpoint discharged loads in the watershed

Point 0.0%

Fraction of point and nonpoint sources to the total

Sediment Non- loads delivered to the Chungju Dam point 100.0 Point % Point 14.5% Point 0.4% 26.3%

T-N T-P Non- Non- point Non- point Sediment 85.5% 73.7% point 99.6% Point Point 26.2% 12.0%

Non- Non- point point T-N 88.0% T-P 73.8% Monthly contribution

30 50 Point Point Nonpoint 45 Nonpoint 25 86% 40 76% 35 20 30

15 25

20 10 15 Monthly T-P load (t/month) T-P load Monthly 10 5 Monthly sediment load (1000 t/month) (1000 load sediment Monthly 5

0 0 JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

3000 Point Nonpoint 2500 72% 2000

1500

1000 Monthly T-N load (t/month) load T-N Monthly 500

0 JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC Conclusions

• Calculation of discharged and delivered loads for each sub-watershed using SWAT model

• Analyzing the transmission characteristics of pollutants through streams

• Assessing the impact of sediment & nutrients export to the Chungju Dam 2010 International SWAT Conference

Thank You !