Hillslope Hydrology and Headwater Control (by Maki TSUJIMURA, Ph.D )

Maki TSUJIMURA, Maki TSUJIMURA, Ph.D.Ph.D.••Associate Professor in Hydrology and Hydrogeology, Doctoral ProgAssociate Professor in Hydrology and Hydrogeology, Doctoral Program in Sustainable ram in Sustainable Environmental Studies, Graduate School of Life and EnvironmentalEnvironmental Studies, Graduate School of Life and Environmental Sciences; Sciences; ••Executive Leader, EDL Education Program, University of Tsukuba Executive Leader, EDL Education Program, University of Tsukuba ••CoCo--ChairholderChairholder, UNESCO, UNESCO--Chair on Sustainable Management of Groundwater in MongoliaChair on Sustainable Management of Groundwater in Mongolia

Environmental Diplomatic Leader (EDL)Environmental Diplomatic Leader (EDL)Education Program, University of TsukubaEducation Program, University of Tsukuba

Contents� Introduction - rainfall runoff process in watershed

� Transformation from rainfall into runoff

� Infiltration

� Runoff characteristics

� Runoff components: End Members Mixing Analysis

� Subsurface flow process in hillslope and runoff

� Role of bedrock groundwater in runoff

� Residence time of groundwater and spring water in headwaters

2

Headwater: Transform from rainfall to

runoff / Recharge-discharge area

3

Runoff

Rainfall

Time

Runoff

Time

Rainfall

Hydrograph

Hyetograph

Evapotranspiration

Groundwater flow

PrecipitationEvapotranspiration

Runoff

Groundwater

Divide

Water balance of watershed(Precipitation)＝(Evapotranspiration)＋(Runoff)＋(Change of storage)

Hewlett and Nutter (1990)

Topographical watershed and

hydrological watershed

Hewlett and Nutter (1990)

Pg: Precipitation, Tf: Throughfall, Cd: Canopy dropped fall, Sf: Stemflow, Ev:

Interception, Tr: Transpiration, Ab: Absorption, Eg Evaporation from soil surface, If:

Infiltration, Of: Overland flow, Pc: Percolation, Gr: Groundwater recharge, Bi:

Bedrock infiltration, Gd: Groundwater discharge

Pg Pg

Sf

Cd Sf

Tf

Cd

Cd

Of

If

PcGr

Gr

GdBi

Bi

Ab

Ab

Tr

Tr

Ev

Ev

Pg Pg

Soil surface

Groundwater table

Bedrock surface

Soil water zone

Groundwater zone

Soil layer

Bedrock

Eg

Storage type

Tipping bucket type

Time

Infiltra

tion c

apacity / R

ain

fall

RI

FIC

IIC

Occurrence of

overland flow

Hortonian overland flow

Infiltration � subsurface flow

Infiltration capacity curve

IIC: Initial Infiltration capacity

RI: Rainfall Intensity

FIC: Final Infiltration Capacity

Infiltration

9

A) Infiltration capacity >

Rainfall intensityB) Rainfall intensity >

Infiltration capacity

Rainfall

Rainfall

Infiltration capacity Infiltration capacity

Infiltration

Infiltration

Percolation Percolation

Hortonian overland flow

Ground surface

Ground

surface

Measurement of infiltration capacity

10

Manual measurement of IC

using a cylinder (Murai, 1970)

Double cylinders (rings)

infiltrometer (Tsujimura

et al., 1991)

Measurement of IC using a

sprinkler (Onda and Yukawa,

1995)

Measurement of IC using a

sprinkler on the tower of 12 m

height (Onda, Tsujimura et al.,

2006)

Water tank

Inner cylinder

Outer cylinder

Soil surface

Water tank

Sprinkler

Tipping bucket

Overland flow collector

Contrasting of forest situation and

infiltration capacity

11

• Contrasting between well maintained forest (right) and no

maintained forest (left) (upper-left).

• Un-perennial watershed without forest maintenance

•Observed runoff during a heavy rainstorm in an un-perennial

watershed

Measurement of infiltration capacity

� Calculation of IC using data of sprinkler

� I = P – Q

� I: IC, P: rainfall intensity, Q: overland flow intensity

12

Comparison of IC among three

different type infiltrometers

(cylinder, sprinkler, tower

sprinkler)

(Onda, Tsujimura et al., 2006)

Exercise 1

13

Time (min.) Infiltration (mL or cm3) IC (mm/hr)

0-1 30

1-2 30

2-3 10

3-4 20

4-5 25

5-6 15

6-7 5

7-8 10

8-9 15

9-10 5

10-12 15

12-14 12

14-16 16

16-18 18

18-20 26

20-25 22

25-30 22

30-35 26

35-40 27

40-45 24

45-50 23

The left table shows data

taken by an infiltration

measurement test using a

cylindrical infiltrometer in a

grassland of U Tsukuba.

Calculate infiltration capacity

at each time step and draw a

graph showing a temporal

change of IC.

Note: Diameter of the cylinder

is 5 cm.

Exercise 1 -Answer

14

15

y = 0.0126x2.3236

R2 = 0.9729

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

1.60

0 2 4 6 8 10Water level (cm)

Discharge (L/s)

Typical weir at stream in headwater

(Hewlett and Nutter, 1970) Example of water level -

discharge relation curve in a

headwater

Water level sensor

(a) A gauging station at Hubbard Brook Watershed

(USA)

(b) A gauging station at Sleepers River Watershed

(USGS)

A weir and parshall flume

at stream of Shiranui

Watershed in Kumamoto,

Japan

A parshall flume at

stream of Shiranui

Watershed in

Kumamoto, Japan

0

5

10

15

20

6-Sep 8-Sep 10-Sep 12-Sep 14-Sep 16-Sep

日付 (2001)

流量 (mm/h)

0

20

40

60

80

100

120

140

160

雨量 (mm/h)

流量

雨量

Date (2001)

Runoff (m

m/h

)

Rain

fall

(mm

/h)

Observed in a headwater, Nikko, Japan

Rainfall

Runoff

Hydrograph and hyetographRunoff characteristics reflecting hydrological processes

18

Urban watershed (0.4

ha) covered by

pavement

RR: 100%Runoff (m

3/h

)

Rain

fall

(cm

/h)

Runoff (m

3/h

)R

unoff (m

3/h

)R

unoff (m

3/h

)

Rain

fall

(cm

/h)

Rural watershed (58

ha) covered by grass

and cultivated area

RR: 3.6%

Forested watershed

(182 ha) covered by

birch and fir underlain

by silt

RR: 3 - 30%Rain

fall

(cm

/h)

Rain

fall

(cm

/h) Watershed in Kenya

(53 ha) by volcanic

ash (no vegetation

information)

RR: 2%

Time (min)

Time (hr)

Time (days)

Time (days)

RR: Runoff ratio

to rainfall in one

rainfall event

Kayane (1980)

19

(b) South western Japan (Kyushu Island)(a) Central Japan (Kanto Plain)Runoff

(mm d

-1)

0.1

1.0

10

100

300

□：Quat. Volc. rock

△：Tertial. Volc. rock

○：Granite

●：Mesozoic

■：Paleozpic

0.5

50

5.0

I II III IV V VI VII

□：Quat. Volc. rock

○：Granite

■：Paleozoic

I II III IV V VI VII

(I) annual maximum runoff, (II) 35-day runoff, (III) runoff with high water level, (IV) runoff with ordinary water level, (V) runoff with low water level, (VI) draught runoff, (VII) annual minimum runoff

20

Onda, Tsujimura et al. (2006)

Runoff

(L s

-1km

-2)

Rain

fall

(mm

h-1)

Days (Sep - Oct, 1993)

Schematic diagram showing

relationship between runoff

characteristics and subsurface

flow processes in shale and

granite watersheds. (Onda,

Tsujimura et al., 1999)

Shale Granite

Delayed response Quick response

Subsurface flow in bedrockSubsurface flow in soil layer

Runoff

Runoff

Rainfall

Soil

layer

Where does water come from?

21

Time

Rainfall

Runoff

Time

Kirchner et al (2001)

Mass balanceEnd Members Mixing Analysis (EMMA)

23

Qn, Cn

Qo, Co

Qt, Ct

Qo, Co

oonntt

ont

QCQCQC

QQQ

+=

+=

t

no

nt

o QCC

CCQ

−

−=

24

Tracer concentration C

Tra

cer concentration C

End member a

Mixture (total discharge)

100

0Contrib

ution ratio o

f end m

em

ber b to

tota

l dis

charg

e (%

)

1000Contribution ratio of end member b to

total discharge (%)

End member b

X%

100-X

%

X% 100-X%

oonntt

ont

QCQCQC

QQQ

+=

+=

t

no

nt

o QCC

CCQ

−

−=

25

Concentration of tracer 1: C1

Concentration of tracer 2: C2

End member aMixture(total discharge)

End member b

End member c1=++ cba QQQ

tccbbaa CQCQCQC 1111 =++

tccbbaa CQCQCQC 2222 =++

Exercise 2

26

Time Runoff

Event water (rainfall)

Pre-event water (groundwater)

The data in the left table shows temporal change of δ18O in stream water (runoff: L/s/km2) during a rainstorm in a small headwater basin, Seto, Aichi, Japan. Calculate contribution rate of pre-event water to runoff water using EMMA and show the results by graph.

t

no

nt

o QCC

CCQ

−

−=

Exercise 2 -Answer

27

Total runoff

Pre-event water component

Granite Watershed

Shale Watershed

28

Case in a headwater� Contrasting runoff components separation using 18O

between the watersheds underlain by shale and granite� Shale watershed: >98% coming from pre-event water

� Granite watershed: 64% coming from pre-event water

Shale Granite

δ18O

(‰)

Runoff (l/s/k

m2)

Rain

fall

(mm

/h)

Shale Watershed

Granite Watershed

31

Stream

Saturation

Divide

Weir

Overland flow

Spring

Stream

Saturation

Divide

Weir

Rain gauge

Observation line

Saturation area: 5% of watershed

Saturation in valley bottom

Observation line on slope

Weir at outlet of watershed

33

0.0

2.0

4.0

6.0

8.0Rainfall (mm/5 min)

285 mm

0 .0

2 .0

4 .0

6 .0

Cl- conc. (m

g/L

)

R a infall: 0 .3 m g/L

0

20

40

60

80

100

Ratio of pre-event water (%)

0

2000

4000

6000

8000

0:00 Sep11 12:00

Sep11

0:00 Sep12 12:00

Sep12

0:00 Sep13 12:00

Sep13

Specific discharge (L/s/km

2)

Pre-event water

2000

(a) Heavy rainstorm (265 mm)

降水量

(mm)

Cl-濃度

(mg L

-1)

地下水成分割合

(%)

比流量

(L s-1km

-2)

地下水成分

降水濃度 0.3

0.0

0.5

1.0

1.5

2.0Rainfall (mm/5 min)

16 mm

0.0

2.0

4.0

6.0

Cl- co

nc. (m

g/L)

Rainfall: 0.7 mg/L

0

20

40

60

80

100

Ratio of pre-event water (%)

0

20

40

60

80

6:00

Oct27

12:00

Oct27

18:00

Oct27

0:00

Oct28

6:00

Oct28

12:00

Oct28

Specific discharge (L/s/km

2)

P re-event water

1999

(b) Small rainstorm (16 mm)

降水量

(mm)

Cl-濃度

(mg L

-1)

地下水成分割合

(%)

比流量

(L s-1km

-2)

地下水成分

降水濃度 0.7

Rain

fall

(mm

)

Rain

fall

(mm

)

Cl-

conc

(mg/L

)

Cl-

conc

(mg/L

)

Gro

undw

ate

r

Ratio (%

)

Gro

undw

ate

r

Ratio (%

)

Runoff (L/s

/km

2)

Runoff (L/s

/km

2)

Groundwater

component Groundwater

component

Rain water: 0.3Rain water: 0.7

Asai (2001)

34

Groundwater tableEqui-potential line

Direction of subsurface

flow

比流量

(L s-1km

-2)

降水量

(mm)

比流量

(L s-1km

-2)

降水量

(mm)

Runoff (L

/s/k

m2)

Runoff (L

/s/k

m2)

Rain

fall

(mm

)

Rain

fall

(mm

)

35

Asai (2001)

y = 0.05x

r2 = 0.84

0.0

1.0

2.0

3.0

4.0

0.0 4.0 8.0 12.0

Peak rainfall (mm/10 min)

Runoff of event water (mm/10 m

in) 総降雨量 265 mmTotal rainfall: 265 mm

Role of bedrock groundwater in

runoff

40

Iwagami, Tsujimura et al. (2010)

Role of bedrock groundwater in

runoff

41

Role of bedrock groundwater in

runoff

42

Iwagami, Tsujimura et al. (2010)

Role of bedrock groundwater

in runoff

43Iwagami, Tsujimura et al. (2010)

Aquitard

不透

水層

Confined aquiferConfined aquifer

Acuitard

Unconfined aquiferUnconfined aquifer

GW table

River Spring

Recharge area

Well

Residence time

1940 1990

CF

Cs

con

cen

tra

tio

n

CFCs in atmosphere

Age in spring / GW

Present

Residence time

in spring / GW

Age Present

Aq

uitard

CFCs (chlorofluorocarbons)CFCs (chlorofluorocarbons)

�CFC-11　(CCl3F, trichlorofluoromethane)

�CFC-12 (CCl2F2, dichlorodifluoromethane)

�CFC-113 (C2Cl3F3, trichlorotrifluoroethane)

0

100

200

300

400

500

600

700

1940 1950 1960 1970 1980 1990 2000

Year

Tra

cer concentration (pptv

) CFC-12CFC-11CFC-113SF6×100

� CFCs is stable in the atmosphere.

� CFCs concentration in the atmosphere is increasing since 1950.

Long trend of CFCs in atmosphere (USGS)

Atmosphere (Fa)

Groundwater (Fg)

Soil surface

Water table

Air in soil (Fs)

Fa

Fs

Fg

iHi pKC = (1)

Ci: CFCs concentration, KH: Henry’s law constant

( )OHii pPxp2

−= (2)

ip : pressure of gas, xi: CFCs mol ratio in atmosphere, P: atmospheric

pressure, pH2O: vapor pressure (Warner and Weiss, 1985)

+

++

+

+=2

321321100100100

ln100

lnT

bT

bbST

aT

aaKH (3)

T: absolute temperature, S: chloride concentration (vol %).

The parameters of a1，a2，a3，b1，b2，b3 are taken from Warner and Weiss

(1985).

Excess air throughfissurs of bedrock Decomposition by microorganism

Aquitard

不透

水層

Confined aquifer

Aquitard

Unconfined aquiferUnconfined GW

CFCs contamination

River Spring

Recharge altitude

Recharge temperature

Well

Urban airThickness of unsaturated zone

Aq

uitard

Age of spring and GW in Mt. TsukubaAge of spring and GW in Mt. Tsukuba(Matsumoto, T., 2009)(Matsumoto, T., 2009)

Geological map (Miyazaki et al., 1996)

Granite

Gabbro

Deposit

Metamorphic

CFC-11（pg/kg）

100

500

1000

CFC-11 concentration

Spatial distribution of CFCs and chemical componentsSpatial distribution of CFCs and chemical components

Chemical characteristics

0

100

200

300

400

500

600

700

1940 1950 1960 1970 1980 1990 2000

Year

Tra

cer concentration (pptv

) CFC-12CFC-11CFC-113SF6×100

Age of spring and GWAge of spring and GW

Granite

Gabbro

Deposit

Metamorphic

Western slope

Southern slope

Age of spring and GW in a mountainous watershed facing ocean Age of spring and GW in a mountainous watershed facing ocean ((OhtaOhta, K., 2008), K., 2008)

Hokuto city,

Yamanashi Pref.

800

1000

1200

1400

1600

18002000

2200：：：：降水降水降水降水：：：：大気大気大気大気サンプルサンプルサンプルサンプル

Headwater of R Jingu

←Spring

　 (J-1)

Main stream→　　　(J-10)

SpringMain stream

BranchWatershed

boundary

R. Jingu

R. Kamanashi

R. OjiraR. Tazawa

R. Matsuyamazawa

Precipitation

Atmosphere

17

18

14

20

J-1

17

1410

14

14

7

12

8

13 10

Branch

Main

stream

Spring

2km

松山沢川 神宮川

田沢川 尾白川

釜無川

：湧水：河川水（本流）

：河川水（支流）：流域界

Age of spring / river waters in low flow

10

19

Spring：14~20 years

Branch:

10~17 years

Main stream:

7~19 years

y = 1.1958x - 8.3709

R2 = 0.7888

0

5

10

15

20

25

0 10 20 30

SiO2 [mg/L]

Resi

dence tim

e [

year

s]

Spring

Main stream

BranchWatershed

boundary

2km

松山沢川 神宮川

田沢川 尾白川

釜無川

：湧水：河川水（本流）

：河川水（支流）：流域界

Age of spring / river waters in high flowAge of spring / river waters in high flow

12

11

7

12

J-1

11

1110

13

11

6

8

11

10 8

Branch

Main

stream

Spring

11

6

15

16J-0

15

15

18

19

Spring:

7~16 years

Branch:

10~19 years

Main stream:

6~18 years

Spring

Main stream

BranchWatershed

boundary

Spring: 14 - 20 years

Branch: 10 - 17 years

Main stream: 7 - 19 years

Spring: 7 - 16 years

Branch: 10 - 19 years

Main stream:

6 - 18 years

Behavior of subsurface Behavior of subsurface

water and residence time water and residence time

in mountainous watershedin mountainous watershed

High flow season

Low flow season

Summary

� Rainfall-runoff characteristics suggest subsurface flow processes occurring in hillslope.

� Groundwater is dominant in runoff during rainstorms in warm humid regions.

� Role of bedrock groundwater is important in runoff during rainstorms in headwater catchments.

� Residence time of groundwater and spring water varies dynamically according with hydrological regime in headwaters.

57