Assessment of sediment and carbon flux in a tropical watershed:the Red River study case (China and Vietnam)

Xi WEI

Supervisors: Sabine SAUVAGE, Jose-Miguel SANCHEZ-PEREZ, Thi Phuong Quynh LE

20th September 2018

1. Context

• Climate: Temperature Precipitation Typhoon El Nino and La Nina …

Impact to:

HydrologySediment

Nutrients Transfer• Human disturbance: Deforestation Urbanization Agricultural Activities Dam Constructions …

1. Context—Sediment

1960-2010 simulated suspended sediment flux(picture extracted from Cohen et al., 2014)

Asia: 30-70% (Le et al., 2007)

1. Context—Carbon

Spatial variation of riverine DOC, POC, and DIC flux (Tg C/yr)(picture extracted from Li et al.,2017.)

POC: particular organic carbonDOC: dissolved organic carbonDIC: dissolved inorganic carbon

The Red River watershed Population density of the Red River(Picture extracted from Le, 2005)

1. Context—The Example of the Red River Watershed in Asia

Land use of different sub-basins(Picture extracted from Le, 2005)

an international riverthe second largest river in Vietnam intensive agricultural activitieshigh population density, urbanization

(Barton et al., 2004; Le et al., 2007; Dang et al., 2010; Vinh et al., 2014; Schoenbohm et al., 2014 ; Lu et al., 2015; Le et al., 2017 )

Dam ManagementMeteorological–hydrological effect

Dams

2010

1989

1972

2010

2010

Daily-scale long-term simulation of Q, SS and C

Different scenarios

1. Context—Recent Studies & Objectives

to better understand the dynamic changes and the key influence factors to quantify the export to the delta part

to develop a comprehensive understanding of the linkage between land use, human activities and climate in the watershed

to predict the future changes to provide the reference and information for the river and agriculture management

Reference:(He et al.,2007; Le et al., 2007 ; Dang et al.,2010; Le et al., 2010; Minh et al., 2010; Vinh et al.,2014; Lu et al.,2015; Le et al., 2017; Hiep et al., 2018)

• Statistic Analysis

• Modelingmonthly scale

daily scale (short period, on delta part, only Q or SS )

(1)IMHE: Institute of Meteorology, Hydrology and Environment, Vietnam(2)TRMM: The Tropical Rainfall Measuring Mission (https://pmm.nasa.gov/TRMM)(3)CFSR: Climate Forecast System Reanalysis (https://globalweather.tamu.edu/)(4)T.P.Q LE: Thi Phuong Quynh Le, Laboratory of Environmental Chemistry, Institute of Natural Product Chemistry, Vietnam Academy of Science and Technology

2. Study Site—The Upstream of the Delta—Inputs and DatabaseArea of the study site: 137 230 km2

Elevation: 3103 to 6 mMean Discharge at the outlet: 3480 m3/s (IMHEN (1), from 1690 to 2010)

Mean Precipitations: 1518-1835 mm/yr (Le et al., 2012; Simons et al., 2016)

Data Type Period Scale Source

Precipitation 1998-2016 daily TRMM (2)

Temperature 1998-31 July 2014 daily CFSR (3)

Q 2000-2010 daily IMHEN

SS 2000-2010 daily IMHEN

POC

Yen Bai: 2008-2010, 2013-2015Son Tay: 2013-2015Hoa Binh: 2008-2010, 2013-2015Vu Quang: 2008-2010, 2013-2015

once/month T.P.Q LE (4)

DOC

Yen Bai: 2003-2004, 2008-2010, 2012-2015Son Tay: 2003-2004, 2013-2015Hoa Binh: 2003-2004, 2008-2010, 2012-2015Vu Quang: 2003-2004, 2008-2010, 2012-2015

once/month T.P.Q LE

Dam Impoundment River Basin(km2)

Capacity(Mm3)

Surface(km2)

Water Level(m)

Mean Depth(m)

Mean Annual Water Discharge

(m3/s)

Maximum Water Discharge

(m3/s)

Hoa Binh 1989 57285 9.5 208 115 50 1781 2400Thac Ba 1972 6170 2.9 235 58 42 191 420

3. Inputs and Database

• SWAT Inputs Data Type Resolution Source

DEM 0.9*0.9 km Shuttle Radar Topography Mission (SRTM)(http://www2.jpl.nasa.gov/srtm)

Soil 0.9*0.9km Harmonized World Soil Database(http://webarchive.iiasa.ac.at/Research/LUC)

Land Use 0.9*0.9km Global Land Cover 2000 database(http://forobs.jrc.ec.europa.eu/products/glc2000)

Subbasins: 242HRU: 1309

4. Results—Water Balance

• precipitation:reference: 1518~1835 mm (T.P.Q. LE et al., 2012; G. SIMONS et al., 2016)

TRMM: 1494mm

• water yield:real: 669mmsim: 693mm

• ETP:reference: 924~1062 mm (T.P.Q. LE et al., 2012)

sim: 1293 mm

• ETA:reference: 832~1117 mm (T.P.Q. LE et al., 2012; G. SIMONS et al., 2016)

sim: 649 mm

46% of Precipitation

43%

4. Result—Monthly Discharge

0

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9

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10

Jul-1

0

Q(m

3 /s)

Yen Bai-Q obs

sim

NSE=0.59, R2=0.82 NSE=0.63, R2=0.75

NSE=0.66, R2=0.75 NSE=0.84, R2=0.87

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Q(m

3 /s)

Hoa Binh-Q obs

sim

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Q(m

3 /s)

Vu Quang-Q obssim

0

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14000

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07

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08

Jul-0

8

Jan-

09

Jul-0

9

Jan-

10

Jul-1

0

Q(m

3 /s)

Son Tay-Q obs

sim

≈22%

≈50%

≈28%

0

10000

20000

30000

40000

50000

60000

70000

80000

Q (m

3 /s)

Hoa Binh-Q obs

sim

NSE=-2.02, R2=0.09

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80000

Q (m

3 /s)

Son Tay-Q obs

sim

0

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20000

30000

40000

50000

60000

70000

80000

Q (

m3 /

s)

Yen Bai-Q obs

sim

NSE=-2.22, R2=0.12

4. Results—Daily Discharge—Calibration in Progress

NSE=-1.63, R2=0.18

0

10000

20000

30000

40000

50000

60000

70000

80000

Q (m

3 /s)

Vu Quang-Q obs

sim

NSE=-1.13, R2=0.14

4. Result—Monthly Sediment ConcentrationNSE=0.52, R2=0.56

NSE=-2.85, R2=0.38NSE=-3.77, R2=0.01

NSE=-5.15, R2=0.57

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SS(m

g/L)

Yen Bai-SS obs

sim

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SS(m

g/L)

Son Tay-SS obs

sim

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SS(m

g/L)

Hoa Binh-SS obs

sim

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10

Jul-1

0

SS(m

g/L)

Vu Quang-SS obs

sim

dam impact

dam impact

≈70%

≈10%

≈20%

4. Results—Daily Sediment Concentration—Calibration in Progress

0

5000

10000

15000

SS(m

g/L)

Yen Bai-SS obs

sim

NSE=-0.10, R2=0.12

0

5000

10000

15000

SS(m

g/L)

Hoa Binh-SS obs

sim

NSE=-0.30, R2=0.01

0

5000

10000

15000

SS(m

g/L)

Son Tay-SS obs

sim

NSE=-4.17, R2=0.04

0

5000

10000

15000

SS(m

g/L)

Vu Quang-SS obs

sim

NSE=-0.29, R2=0.01

4. Results—Suspended Sediment Flux

Annual water and suspended sediment discharge (1960-2010)(Picture extracted from Vinh et al., 2014 )

Yen Bai

Vu Quang

Hoa Binh

Son Tay

simulation period: 2000-2010dam implement

dam implement

11 times!

2.5 times!

39.6×106 ton/yr

63.1×106 ton/yr

3.2×106 ton/yr

14.8×106 ton/yr

Scenario: without dam

112.1×106 ton/yr1.8 times!

55.1×106 ton/yr17 times!

5. Methodology for Calculating DOC and POC

𝐷𝐷𝐷𝐷𝐷𝐷 =a𝑄𝑄

𝑏𝑏 + 𝑄𝑄

DOC-mg/L; Q-mm/day(Jonhson et Goody, 2011; Fabre et al., submitted)

DOCsimab

Qobs

Qsim Qsim

QobsFluxobs

FluxsimDOCobs

%POC =9.40𝑆𝑆𝑆𝑆 − 𝑎𝑎

+ 𝑏𝑏

%POC-the part of POC (mg C/L) in the SS; SS-mg/L

(Boithias et al., 2014; Fabre et al., submitted)

ab

SSobs

SSsim SSsimFluxsimPOCsimPOCobs

DOC : Dissolved organic carbonPOC : Particulate Organic Carbon

6. Results—DOC Concentration

0

1

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7

0 1 2 3 4 5

DOC

(mg/

L)

Q (mm)

Yen Bai

b=0.18

a=3.8

0

1

2

3

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5

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7

0 1 2 3 4 5

DOC

(mg/

L)

Q (mm)

Son Tay

b=0.59

a=4.9

0

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5

6

7

0 1 2 3 4 5

DOC

(mg/

L)

Q (mm)

Hoa Binh

a=2.7

0

1

2

3

4

5

6

7

0 1 2 3 4 5

DOC

(mg/

L)

Q (mm)

Vu Quang

b=0.11

a=3.3𝐷𝐷𝐷𝐷𝐷𝐷 =

a𝑄𝑄𝑏𝑏 + 𝑄𝑄

DOC-mg/L; Q-mm/day(Jonhson et Goody, 2011; Fabre et al., submitted)

b=0.18

lack of sampling data in high flood days

0

1

2

3

4

5

6

21-Ja

n-03

15-A

pr-0

3

15-Ju

l-03

15-O

ct-0

3

19-Ja

n-04

15-A

pr-0

4

20-Ju

l-04

20-O

ct-0

4

15-Ja

n-08

15-A

pr-0

8

15-Ju

l-08

23-S

ep-0

8

12-D

ec-0

8

19-M

ar-0

9

15-Ju

n-09

15-S

ep-0

9

5-De

c-09

15-M

ar-1

0

15-Ju

n-10

15-S

ep-1

0

6-De

c-10

DOC

(mg/

L)

Yen Bai-DOC obs DOC

sim DOC

NSE=-0.42, R2=0.0005

NSE=-0.74, R2=0.04

0

1

2

3

4

5

6

20-Ja

n-03

15-F

eb-0

315

-Mar

-03

15-A

pr-0

315

-May

-03

15-Ju

n-03

15-Ju

l-03

15-A

ug-0

315

-Sep

-03

15-O

ct-0

315

-Nov

-03

16-D

ec-0

319

-Jan-

0424

-Feb

-04

mar

ch15

-Apr

-04

6-M

ay-0

423

-Jun-

0420

-Jul-0

418

-Aug

-04

15-S

ep-0

420

-Oct

-04

15-N

ov-0

42-

Dec-

04

DOC(

mg/

L)

Son Tay-DOC obs

sim

0

1

2

3

4

5

6

1-Ja

n-00

4-Ja

n-00

7-Ja

n-00

10-Ja

n-00

13-Ja

n-00

16-Ja

n-00

19-Ja

n-00

22-Ja

n-00

25-Ja

n-00

28-Ja

n-00

31-Ja

n-00

3-Fe

b-00

6-Fe

b-00

9-Fe

b-00

12-F

eb-0

0

15-F

eb-0

0

18-F

eb-0

0

21-F

eb-0

0

24-F

eb-0

0

27-F

eb-0

0

1-M

ar-0

0

DOC(

mg/

L)

Hoa Binh-DOC obs DOC

sim DOC

NSE=-0.07, R2=0.00005

0

1

2

3

4

5

6

1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51 53 55 57 59

DOC(

mg/

L)

Vu Quang-DOC obs

sim

NSE=-0.33, R2=0.0008

6. Results—DOC Concentration—In Progress

6. Results—POC Concentration—In Progress

0

5

10

15

20

25

0 100 200 300 400 500 600 700 800

%PO

C

SS(mg/L)

Yen Bai

0

10

20

30

40

50

60

0 50 100 150 200 250 300

%PO

C

SS(mg/L)

Vu Quang

a=5.7; b=1.50

0

10

20

30

40

50

60

0 50 100 150 200

%PO

C

SS(mg/L)

Son Tay

a=3.0; b=2.00

0

10

20

30

40

50

60

70

80

90

100

0 50 100 150 200

%PO

C

SS(mg/L)

Hoa Binh

a=1.5; b=1.00

a=20.0; b=1.20

%POC =9.40𝑆𝑆𝑆𝑆 − 𝑎𝑎

+ 𝑏𝑏

%POC-the part of POC (mg C/L) in the SS; SS-mg/L

(Boithias et al., 2014; Fabre et al., submitted)

0

2

4

6

8

10

12

14

POC

(mg/

L)

Yen Bai-POC obs POCsim POC

0

1

2

3

4

5

POC

(mg/

L)

Hoa Binh-POC obs POC

sim POC

-2

0

2

4

6

8

10

12

14

POC

(mg/

L)

Vu Quang-POC obs POC

sim POC

6. Results—POC Concentration

7. Conclusions and Perspectives

• SWAT presents a good simulation on monthly scale, and better simulation on discharge than on sediment concentration. This shows the big impact of the dam on sediment. And this conclusion can also be proved by the scenario simulation result.

• In order to better simulate the DOC and POC, it’s very necessary to work on daily scale as monthly scale might ignore the dynamic changes from day to day. And now we are in progress to get a good simulation of Q and SS on daily scale.

• POC shows a clear tendency and fits the equation well while DOC doesn’t. This is might due to the lack of sampling data during high discharge days.

Thanks for Your Attention

QuestionsSuggestion

4. Methodology

Parameter Input File Definition Range Calibrated Value

PRF .BSN Peak rate adjustment factor for sediment routing in the main channel 0-2 2

SPCON .BSN Linear parameter for calculating the maximum amount of sediment that can be reentrained during channel sediment routing 0.0001-0.01 0.0002

SPEXP .BSN Exponent parameter for calculating sediment reentrained in channel sediment routing 1-2 2ALPHA_BF .gw Baseflow alpha factor (1/days) 0-1 0.015GW_REVAP .gw Groundwater "revap" coefficient 0.02-0.20 0.15REVAPMN .gw Threshold depth of water in the shallow aquifer for “revap” or percolation to the deep aquifer to occur (mm H2O) 0-1000 650RCHGR_DP .gw Deep aquifer percolation fraction 0.0-1.0 0.01GWQMN .gw Threshold depth of water in the shallow aquifer required for return flow to occur (mm H2O). 0-5000 800

GW_DELAY .gw GW_DELAY Groundwater delay time (days). 0-500 40CN2 .mgt Initial SCS runoff curve number for moisture condition II 35-98 *0.95

SOL_AWC .sol Available water capacity of the soil layer (mm H2O/mm soil) 0-1 *1.2CH_COV1 .rte The channel erodibility factor -0.05-0.6 0.6CH_COV2 .rte Channel cover factor -0.001-1 1

• Parameter Setting