Progress within the F-TRACE Project

Environmental Research Group Fukushima Environmental Safety CenterJapan Atomic Energy Agency (JAEA)

2nd Caesium Workshop: meeting challenges for Fukushima recovery on 6th Oct. 2014

We are here!

Tadafumi NIIZATO, Takahiro NAKANISHI, Hironori FUNAKITadahiko TSURUTA and Kazuki IIJIMA

Objectives of the F-TRACE project 2

AdvectionAdvection

Transport / accumulation in a river system

Transport pathways & processes

Develop phenomenological models to describe quantitatively transport of radioisotopes(especially radioactive Cs) along water systems

y

Desorption / coagulation by saline waterTransport by ocean currents

Transport behavior of Cs to be modeled

Behavior of radioCs flowing into living-sphereevaluate external irradiation in the living-sphere

Behavior of each species of radioCs in river system evaluate internal exposure by intake of water

apply to evaluate Cs uptake by agricultural/aquatic products

Behavior of each species of radioCs in forests evaluate external irradiation of forestry workers apply to evaluate cycle of Cs in forested ecosystem

Erosion

transportpsedimentation

Soil loss

Processes of soil loss

Air dose rate/h, 31st May, 2011

Current research area for river systems

Forest (4 fields)Kawamata deciduous forestNamie evergreen / deciduous forestsOkuma evergreen forestKawauchi evergreen / deciduous forests

River and estuary (7 river systems)Ohta since 2014 high Cs depositionOdaka without dam brakish waterUkedo high Cs deposition

Takase without dam high Cs depositionMaeda without dam high Cs depositionKuma without dam

OhgawaraTomioka

Oginosawa through decontaminated areaKido through decontaminated area

Dam lake and pond (5 dam lakes)Yokokawa since 2014 Ohta riverOhgaki Ukedo riverSakashita since 2014 Ohgawara riverTakigawa Tomioka riverOgi Oginosawa riverPonds for irrigation

FDNPP

5 km

N

W

N

W

Research area Forest River / estuary Dam lake / pond

Takigawa dam

Ogi dam

Ohgaki dam

Ponds in Okuma

Ponds in Futaba

Kawamata

Kawauchi

Namie

Okuma

Odaka riv.

Ukedo /Takase riv.

Maeda riv.

Kuma /Ohgawara riv.

Tomioka /Oginosawa riv.

Kido riv.

Ohta riv.

Sakashita dam

Yokokawa dam

3

Fukushima

TopographyGeospatial information

authority of Japan

Ele

vatio

n [m

]

Coloured relief map is basedon the 10 m DEM of Basemap information by GSI

Current research area for river systems

4

Forest (4 fields)Kawamata deciduous forestNamie evergreen / deciduous forestsOkuma evergreen forestKawauchi evergreen / deciduous forests

River and estuary (7 river systems)Ohta since 2014 high Cs depositionOdaka without dam brakish waterUkedo high Cs deposition

Takase without dam high Cs depositionMaeda without dam high Cs depositionKuma without dam

OhgawaraTomioka

Oginosawa through decontaminated areaKido through decontaminated area

Dam lake and pond (5 dam lakes)Yokokawa since 2014 Ohta riverOhgaki Ukedo riverSakashita since 2014 Ohgawara riverTakigawa Tomioka riverOgi Oginosawa riverPonds for irrigation

FDNPP

5 km

N

W

N

W

Dose rate/h, 31st May, 2011

Research field Forest River / estuary Dam lake / pond

Takigawa dam

Ogi dam

Ohgaki dam

Ponds in OkumaPonds in Futaba

Kawamata

Kawauchi

Namie

Okuma

Odaka riv.

Ukedo /Takase riv.

Maeda riv.

Kuma /Ohgawara riv.

Tomioka /Oginosawa riv.

Kido riv.

Ohta riv.

Sakashita dam

Yokokawa dam

4

Fukushima

5Overview of the numerical models

1D/2D river models: TODAM, iRIC

3D reservoir/coastal models: FLESCOT, ROMS

Soil and Cs transport model: SACT

Amounts from upper stream and sides

Amounts from land surface

Amounts from rivers

Future radio-cesium distribution map

Future radio-cesium distribution on river basins

Future radio-cesium distribution on

coastal field Air dose evaluation models:PHITS, MCNP

Forest investigation

6

Ogi, Kawauchi(deciduous broad-leaved forest)

Ubagami, Okumaevergreen coniferous

forest & deciduous broad-leaved forest

Ogi, Kawauchi(evergreen

coniferous forest)

7

Kawauchi

Fukushiam

10 km

N

W

N

W

Vegetation Topography Soil1)Kawamata Town, Sakashita

Deciduous broad-leaved forest

South-facing valleyGentle to steep slope

Brown forest soil

2) Namie Town, Kawafusa (Ukedo River & Ogaki dam lake)

Evergreen needle-leaved forest (lower stream)Deciduous broad-leaved forest (upper stream)

East-facing valley, steep slopeGully erosion Transported

soil

3) Okuma Town, Ubagami (Kuma River)

Evergreen needle-leaved forest

North-facing, gentle to intermediate slopeGully erosion

Brownforest soil (thick A horizon)

4) Kawauchi Village, Ogi (Ogi dam lake)

< Ogi A >Evergreen needle-leaved forest

North-facing valleyIntermediate to steep slope

Brown forest soil

< Ogi B >Evergreen needle-leaved forest

South-facingvalleySteep slope

Brown forest soil

< Ogi C >Deciduous broad-leaved forest

South-facing slopeIntermediate to steep slope

Brown forest soil (thick organic layer)Transportedsoil

1) Sakashita,Kawamata

4) Ogi,Kawauchi

2) Kawafusa,Namie

3) Ubagami,Okuma

Ogaki dam lake

KumaRiver

Ogi dam lake

Namie

Okuma

Coloured relief map is based on the 10 m DEM of Base map information by GSI

Forest: Investigation area 7

Forest : Investigation area

Ogaki dam lake

Fukushima5 kmN

W

N

WW

KumaRiver

Ogi dam lake

Dos

e ra

te, 1

m a

bove

gr

ound

sur

face

[/h

]

19.5 9.5 – 19.03.8 - 9.51.9 - 3.81.0 - 1.90.5 - 1.00.2 - 0.50.1 - 0.2

0.1

Distribution Map of Radiation Dose

- Airborne monitoring -

MINISTRY OF EDUCATION,CULTURE, SPORTS,SCIENCE AND TECHNOLOGY JAPAN

Sakashita,Kawamata

Ogi,Kawauchi

Kawafusa,Namie

Ubagami,Okuma

8

Vegetation Topography Soil1)Kawamata Town, Sakashita

Deciduous broad-leaved forest

South-facing valleyGentle to steep slope

Brown forest soil

2) Namie Town, Kawafusa (Ukedo River & Ogaki dam lake)

Evergreen needle-leaved forest (lower stream)Deciduous broad-leaved forest (upper stream)

East-facing valley, steep slopeGully erosion Transported

soil

3) Okuma Town, Ubagami (Kuma River)

Evergreen needle-leaved forest

North-facing, gentle to intermediate slopeGully erosion

Brownforest soil (thick A horizon)

4) Kawauchi Village, Ogi (Ogi dam lake)

< Ogi A >Evergreen needle-leaved forest

North-facing valleyIntermediate to steep slope

Brown forest soil

< Ogi B >Evergreen needle-leaved forest

South-facingvalleySteep slope

Brown forest soil

< Ogi C >Deciduous broad-leaved forest

South-facing slopeIntermediate to steep slope

Brown forest soil (thick organic layer)Transportedsoil

9

Soil (field investigation, lab analysis)Soil type, distribution, soil horizon sequence, sampling, grain size distribution, mineral composition, radioCs concentration

Vegetation field investigation, remote sensingTree species, height, tree density, undergrowthLitter fall, liter composition, litter samplingVegetation and land use mapping

Topography field investigation, DEM analysis)Topographic surveying, micro topography & its distributionSlope map, slope orientation map, sedimentation point

Tree height measurement

Forest: Site characteristics and radioCs distribution

Relationship among vegetation-topography-soil characteristics-radioCs concentration & distributionConceptualisation of real transport processes of radioCs

Vegetation map

[m]Investigation area

Japanese cedar

Red pine

Hardwood

Deciduous shrub

Transport processDose rateForest floor, slope

Dose rate measurement

Soil loss on the mountain slope

Soil sampling by scraper platesampling interval: 1 cm

ation

Soil thickness measurement by penetration test

10

ca.6 m

Rainfall (gross precipitation)

ThroughfallStem flow

Surface runoff & Soil loss

Transport of radioCs with Surface runoff & Soil losson the forest slope

Assessment of radioCs input and output in the forest floor per unit period and area from

forest [ex. Bq/m2/year]

ca. 20 cm height

Precipitation gauge

Stem flow tank (70 L)

Tanks for soil & water catchment (200 L x 2)

Water Level gauge

Water level gauge

Solar battery panel

Turbidity gauge

Triangular weir(W 30cm, H 25cm, D 60cm)

Water sampler(10 L) (throughfall)

Forest : Monitoring of surface runoff and soil loss

Gauge ofsoil moisture

Flowing into river system

Forest: Transport and sedimentation processes in the forest floor

Transport & sedimentation processes

by RainfallRainfall run-off (overland flow, downslope flow)Raindrop erosionStem flowLitter flow (run-off over the litter layer, esp. broad-leaved forest)Rainy season July to OctoberWhole forested area

by Frost actionFreezing and thawing action (frost heave, frost creep)Downslope transport of thawing soil Winter season (December, January to February)South-facing forested area, thin litter layer

by Mass movementSmall-scale mudslideVery steep forest slopeMainly, rainy season and snowmelt season (late Feburary to March)Small area in the forest

by Snow movement and Snow melting

Erosion by melting waterShaving and grooving of top soilSnow season and snow melt seasonSmall area in the forest

11

20cm20cm

Outflow of soil at the base of tree

Soil pillar by raindrop erosion

Sedimentation of litter at the forest edge

Downslope slip of thawing soil

Mudslide on the gully slope

Sampling point

Forest: Depth distribution of radioCs (Evergreen coniferous forest)

NN 50 mA

B

0 20 40 60 80 100 120

Distance [m]

380

400

420

Elev

ati

AB

Red Relief Image Map, patent technology by Asia Air Survey Co.Ltd.

Contour intervals: 1 m Sample No. : PAK-1,

at crest flat

Brown forest soil Sampling date: January 2013

12

Dep

th [c

m]

Concentration [kBq/kg]

Dep

th [c

m]

Concentration [kBq/kg]

Dep

th [c

m]

Concentration [kBq/kg]

Sample No. : SUP-6• Footslope• Slope dip: 16• Litter layer: 9 cm

Dep

th [c

m]

Cs-137 Cs-137

Sample No. : SUP-4• Sideslope• Slope dip: 30• Litter layer: 2.5 – 3 cm

Sample No.: SUP-1• Crest flat• Slope dip: 8• Litter layer: 3.5 cm

Cs-137

Dep

th [c

m]

Sideslope ( =1.24)Footslope ( =0.55)

0

Dep

th [c

m]

Concentration [kBq/kg]

Cx = C0 exp(- )+Q

<Schematic diagram>

Kawauchi

Fukushiam

10 km

N

W

N

W

Ogaki dam lake

Ogi dam lake

Namie

Okuma

Coloured relief map is based on the 10 m DEM of Base map information by GSI

Snow season

Snowseason

JMA: Tsushima

Annual precipitation- average in the past 30 years 1,345.9 mm- 2011 1,211 mm 2013 1,374 mm

Observation period at KA-plot

13

Sakashita,Kawamata

Town

Ogi,Kawauchi

Village JMA: Kawauch

[mm]

Annual precipitation- average in the past 30 years 1,511 mm- 2011 1,320 mm 2013 1,234 mm[mm]

Observation period at KE-plot

Forest: Precipitation near the observation plot (AMeDAS, Japan Meteorological Agency)

0

100

200

300

400

J F M A M J J A S O N D

0

100

200

300

400

J F M A M J J A S O N D

<Ogi, Kawauchi Village_KA-plot>Outflow of radioCs: 1,100 Bq/m2/yearOutfow rate of radioCs: 0.2 % per year

<Sakashita, Kawamata Town_KE-plot>Outflow of radioCs: 470 Bq/m2/yearOutfow rate of radioCs: 0.1 % per year

JMA: Tsushima

JMA: Kawauch

Rain fal l

Stem

flow

Leaf

(litt

er) f

all

Leaf

drip

Thro

ughf

all

Gross precipitationNot detectable(less than 1.8 Bq/L)

Stem flow 27-175 L/m2 yrInput to the forest floor

21 268 Bq/m2 4 weeksDeciduous broad-leaved forest;

78 – 310 Bq/m2 4 weeks

Litter fall(pre-existing data in )

Input to the forest floorJapanese cedar forest

3,125 4,250Bq/m2 4 weeks

1,238 Bq/m2 4 weeks

Surface runoff1.1 L/m2 4 weeks (Sept.)Output from forest floor

18 - 28 Bq/ m2 4 weeks

Soil loss (rainy season)1.2 - 4.2 g/m2 4 weeksOutput from forest floor36 - 84 Bq/m2 4 weeks

14

Infil

trat

ion

Surface runoffSoil loss

Throughfall756 mm/yr (Japanese Cedar, Kawauchi)Input to the forest floor

155 Bq/m2 4 weeks

Relatively higher pH in forest soil in the vicinity of the stand

InputInput

Output

Input

Input

Gro

ss

prec

ipita

tion

I tut

Forest floor: Input (104) Output (101 - 102)[Bq/m2 4 weeks]

Forest: Input - output budget of the mountain forest

Depth profiles of radioCs are related to the geomorphology,mainly exist until 5 cm depth

River investigation

15

Kuma River, Okuma Town

upstream

Odaka River, Minami-soma City

downstream & river mouth

Ukedo River, Namie Townmiddle stream

River: Items of observation and how to use data

Investigation Data set Parameters after data processing

How to use dataEvaluation of

mass flowUnderstanding

mechanism Input for TODAM, etc. Verification of TODAM, etc.

Perio

dica

l

Surveying ShapeDose rate measurement Dose rate

River measurements Flow rateTurbidity

Flow velocity

Water sampling

SS conc.Cs conc.SS sizeSS mineralOther ions

Kd of Cs on SS

Sampling flood plain sediment

Cs conc.SizeMineral

Kd of Cs on sediment

Sampling soil fordepth profile evaluation

Cs conc.SizeMineral

Cs deposition in soil Continuous measurement

Water levelTurbidity

Hig

h w

ater

leve

l Flow rate

Water sampling

SS conc.Cs conc.SS sizeSS mineralOther ions

Water level Flow curveFlow rate SS conc.&size

Flow rate SS Kd

16

p g psediment Size

Sampling of river water & river bed sediments

Measurement of flow rate & turbidity

Topographical surveying

Survey line

Sampling of soil at flood channel (scraper plate)

pu V ifi ti f

Automatic observation of water level & turbidity in river

Flow rate measurement

17

Dose rate /h

gravel

sandmudmud

0.4-0.70.7-1.01.0-1.31.3-1.61.6-1.91.9-2.22.2-2.52.5-2.82.8-3.13.1-3.4

mudSand-gravel

MidstreamODAR-5

Channel

Deposition of fine-grained soil particle at the high water levelVegetation cover

relatively higher dose rate and Cs concentration

No deposition of fine-grained soil particlesrelatively lower dose rate & Cs conc.

ca.1.5 m1m 1cm

5.7-6.8 kBq/kg wet2.2 kBq/kg wet

0.3 kBq/kg wet11 kBq/kg wet

River: Dose rate distribution in the flood plain, Odaka river

Flood plain

1 m

10 m

position of fine grained

q g

River channel

Right bank

Deposition of fine gr

Flood plain

middle March 2013

Left bank

18River Evolution of dose rate distribution in the flood plain, Ukedo

Relatively higher dose rate in the flood plain

Dose rate gradually decrease in general

left

Air dose rate

10.51 - 11.60 9.41 - 10.51 8.31 - 9.41 7.22 - 8.31 6.13 - 7.22 5.03 - 6.13 3.94 - 5.03 2.84 - 3.94 1.75 - 2.84 0.65 - 1.75

late Sept. 2013

DownstreamUKER-2

late Jan. 2013

Left bank Right bank

late Nov. 2013

1m 1cm

Dose rate /h

right

2 m

20 m

Channel Flood plain

19

Air do

2.9 2.7 2.5 2.3 2.1 1.9 1.7 1.5 1.3 1.1

late Nov. 2013

late Sept. 2013

River Evolution of dose rate distribution in the flood plain Ogi

2 m

2 m

Mountain riverOGIR-3

Leftbank

Rightbank

Leftbank

Rightbank

middle March 2013

1m 1cm

Dose rate /h 2.92 - 3.12 2.73 - 2.92 2.53 - 2.73 2.33 - 2.53 2.13 - 2.33 1.94 - 2.13 1.74 - 1.94 1.54 - 1.74 1.35 - 1.54 1.15 - 1.35

ChannelFlood plain

Mountain forest (edge)

Relatively higher dose rate near the bottom of mountain slope & river wall

Decontamination & typhoon event (June to Sept. 2013)

No deposition of fine-grained soil particles in the flood plain

relatively low dose rateRelatively higher dose rate in the mountain slope & near the bottom of river wallTransportation and accumulation

of fine-grained soil particles

Accumulation of Cs-137 in the Flood plain & the area of high vegetation cover rateNo accumulation near the channel

20River: Inventory of Cs-137 on the flood plain, Ukedo river

0

20

40

60

80

100

0 500

20

40

60

80

100

120

140

160

0 50 100 150

137Cs conc.(kBq/kg) 137Cs conc.(kBq/kg)

Mas

s de

pth

(kg/

m2 )

6,800kBq/m2

137Cs conc.(kBq/kg)

0

20

40

60

0 50 100 150 200

3,000kBq/m2

0

20

40

60

80

100

0 50 100 150

137Cs conc. (kBq/kg)

1,400kBq/m2

340kBq/m2

1m 1cmDose rate /h

137C (kB /k )

Midstream UKER-10

1 m

10 m channel

21

30001000 - 30000600 - 10000300 - 6000100 - 3000060 - 1000030 - 600010 - 30000 0010

Deposition densities of Cs-137

[kBq/m2](as of March 2013)

Odaka riv.

Ukedo riv. & Takase riv.

Maeda riv.

Kuma riv.

Tomioka riv. & Ogi-no-sawa riv.

without damInflow of sea water at the river mouth

with dam (Ukedo riv.)without dam (Takase riv.)relatively higher Cs inventory in the watershed area

without dam

Flowing through thedecontaminated area

without damrelatively higher Cs inventory in the watershed areainflow of sea water at the river mouth

Inventory of Cs-137 in the flood pain of downstream depends on the condition of Cs-137 accumulation in the watershed area due to the transportation of the sediments

River Inventory of Cs-137 in the flood plain (Sept. to Dec. 2013)

22

12 10 8 6 4 2 0

12 10 8 6 4 2 0

12 10 8 6 4 2 0

12 10 8 6 4 2 014

12 10 8 6 4 2 014

35 30 25 20 1015 540 0

Odaka riv. flood plain airborne survey

Ukedo riv. flood plain airborne survey

Takase riv. flood plain airborne survey

Maeda riv. flood plain airborne survey

Kuma riv. flood plain airborne survey

Tomioka riv. flood plain airborne survey

Cs-

137

(kB

q/m

2 )

Cs-

137

(kB

q/m

2 )

104

103

102

100

101

105

104

103

102

100

101

105

104

103

102

100

101

105

104

103

102

100

101

105

104

103

102

100

101

105

104

103

102

100

101

105

N=3-6 at each point

N=3-6 at each point

N=3-6 at each point

N=3-6 at each point

N=3-6 at each point

N=3-6 at each point

River Inventory of Cs-137 in the flood plain (Sept. to Dec. 2013)

Distance from river mouth (km)Distance from river mouth (km)

upstream downstream upstream downstream

23

0

100

200

300

400

500

600

0 100 200 300 400

Cs-

137

conc

. in

Ss(k

Bq/

kg)

Turbidity (mg/L)

ODARUKERTAKRMAERKUMRTOMROGIR

Concentration of Cs-137 in suspended sediment (Ss) decreased with increase in Ss concentration.

This tendency can be explained by the increase of particle size of Ssaccompanied with increase of flow rate.

Dependency of distribution coefficients on the particle size of Ss can be modeled.

River Turbidity vs Cs conc. of suspended sediment (Ss)

Odaka riv.Ukedo riv.Takase riv.Maeda riv.Kuma riv.Tomioka riv.Ogi-no-sawa riv.

Dam lake investigation

24

Ogi dam lake, Kawauchi Ogaki dam lake, Namie TownTakikawa dam lake,Tomioka Town

Core loggingundisturbed sampling

Water sampling(Heyroth sampling bottle)

Core loggingGravity core sampler

Dam lake: Sampling of bottom deposits and dam water

Sampling of sinking particles(sediment trap)

and Measurement of

flow directionflow rate

turbidity in the dam lake

*Installation of ADCP (Acoustic Doppler Current Profiler)

Input & validation data sets for the simulation

25

0

10

20

30

40

0 50,000 100,000 150,000 200,000 250,000 300,000

Dep

th fr

om th

e bo

ttom

[cm

]

Cs-137 concentration [kBq/kg]

St.1 (middle Oct. 2013)

0

10

20

30

400 100,000 200,000 300,000

Dep

th [c

m]

St.4 (late Oct. 2013)

0

10

20

30

40

0 100,000 200,000 300,000

Dep

th [c

m]

Cs-137 concentration [kBq/kg]

St.C(middle Jan. 2012)

St.C

St.4

St.1

Dep

th fr

om th

e bo

ttom

[cm

]

100 200 300

100 200 300

100 200 300

0 100 200 [m]

Elev

atio

n [m

]

Inflow from river

Contour interval: 1 m

Dam lake: Cs-137 conc. of the dam lake deposits, Ogi

Decrease in Cs-137 concentration of the uppermost part of the lake deposits

Decrease in Cs-137 concentration of soil flowing from the river to the dam lake

26

01020304050607080

0 200,000 400,000 600,000 800,000

Dep

th [c

m]

Cs-137 concentration [kBq/kg], dry

St.2(early Nov. 2013)

0

10

20

30

40

50

60

70

80D

epth

[cm

]

St.7(late Oct. 2013)

0

10

20

30

400 200,000 400,000 600,000 800,000

Dep

th [c

m]

St.10(late Oct. 2013)D

epth

from

the

botto

m [c

m]

St.7

St.2

St.10

<100100-150150-200200-250250-300300-320320-350350-380380-400400-450450-500

Elevation [m]

Red contour Blue contourStatus Filled Partially filled

Water level (depth) 170 m (33.5 m) 140 m (3.5 m)

N

W

N

W 200 400 600 800

200 400 600 800

Dam

Dam lake: Cs-137 conc. of the dam lake deposits, Ogaki

Inflow from river

Contour interval: 5 m

Contours above water level is based on the results of the airborne laser scanning survey by GSI

Total accumulation of Cs-137 in the lake deposits is relatively higher in the upstream and lower in the downstream

Deposition after the accident

27

Behavior of radCs in the mountain forest to dam lake 28

Throughfall2 Bq/L

Soluble Cs in the lake water< 0.01 Bq/LSurface of topsoil

30 kBq/kg

Surface of lake deposits10 kBq/kg

S

Erosion

Sedimentation

Overview of observation results in Ogi region of Kawauchi village. Cs-137 concentrations were also shown.

0

10

20

30

400 100,000 200,000 300,000

Dep

th [c

m]

Concentration [kBq/kg]

100 200 300

0 100 200 300

Cs-137

Maximum peak at several tens cm depth in the lake deposits

Deepest(St.4)

D t

Annual discharge of Cs by surface runoffapprox. 0.2 % of the total amount of Cs in the topsoil

Dep

th [c

m]

Concentration [kBq/kg]

Sample No. : SUP-6• Footslope• Slope dip: 16• Litter layer: 9 cm

Dep

th [c

m]

Cs-137

Most of Cs existed within 5 cm depth.

Stem flow30 Bq/L

29

0

20

40

60

80

0 200 400 600 800

Dept

h cm

Concentration kBq/kg Inflow (St.2)

flowfl

Surface of lake deposits100 200 kBq/kg

Estuary sediment (silt)1 5 kBq/kg

0

20

40

60

80

0 200 400 600 800

Dept

h cm

Concentration kBq/kg Outlet (St.7)

80

Maximum peak at several tens cm depth in the lake deposits.

large size fraction

Maximum peak at several cm depth in the lake deposits.

small size fractionDepth profile of Cs concentration in the

bottom sediment of Ogaki dam lake.

Behavior of radCs in the dam lake, river system and estuaryOverview of observation results in Ukedo river system of Namie Town. Cs-137 concentrations were also shown.

Soluble Cs in the lake water0.12 Bq/L

Evolution of dose rate distribution in the flood plain

Cs-137

Cs-137

Flood plain100 kBq/kg

no slightly increaseg yg y

River bed:10 kBq/kg

decrease

Quality control of data

Quality management

Database management

Assessment periodPresent year decade 30

years

Spat

ial s

cale

Min

or b

asin

5,

000

– 10

,000

m2

Mid

dle

to M

ajor

bas

in

10,0

00 m

2 to

who

le o

f Ab

ukum

a M

ts.)

Field investigation/monitoring -Data acquisition for model construction and numerical simulation (Field investigation, monitoring of surface runoff/soil loss/dose

ratio)

Forest/River(long-term) - Soil loss in forest USLE model - Transport & deposition in

river 1D model (TODAM code)

Evaluation of radiation exposure (i) Simplified evaluation system (ii) Detailed evaluation system

Evaluatio(i) i

Forest/River (short-term, detailed

modelling) - Soil loss in forest;

Watershed model - Transport &

depositional behavior in river: 2~3D model (iRIC codes)

Quality c

Qualimanage

Databamanagem

river 1D model (TODAM code)

rt-( h

- Reservoir sedimentation -2~3D model (FLESCOT, iRIC)

- River mouth & coastal area -2~3D model (FLESCOT, SWAN,

and ROMS codes)

- setting up and optimization of parameters (input from

investigation results)

Field data

- Confirmation of adequacy of analytical results (input from analytical results)

Remote sensing Vegetation:

-Mapping of forest type: tree species & height, etc.

-Extraction of vegetation anomaly Geomorphological characteristics:

-Data acquisition for digital elevation model

-Topographical analysis: orientation & gradient of slope, relief energy, valley density, shape of water shed

Land use: Classification of surface cover

Extraction of representativeness and uniqueness of the investigation area

Clarify the range and limit of applicability of analytical results

Meteorological data analysis Regional differences of rain fall, wind direction/velocity, air temperature, humidity, etc.

Identification of need for additional investigation/analysis Determination of additional investigation/simulation items and areas

GIS* USLE: Universal Soil

Loss Equation

30Application of analysis method appropriate to the spatial and assessment scales, combination with GIS analysis

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SummaryTransport behaviors of radioCs in the forests, river systems, dam lake,

ponds and estuary were investigated mainly in Abukuma mountains and the coastal area of Fukushima Prefecture, FY2013Consequently,

Annual discharge of radioCs from the topsoil of the mountainous forest by runoff was estimated to be 0.2 % of the total amount of radioactive Cs in the topsoil.

Accumulating behavior of radioCs in the river system was clarified.

River: fine sediments with high Cs concentration in the flood plain

Dam lake: thick coarse sediments with low Cs concentration near the inflow point

thin fine sediments with high Cs concentration near the outlet

Concentration of radioCs in the river bed tended to decrease with the elapse of time.

Compared to the concentration of radioCs in the dam lake sediments, that of lake water was of extremely low.

e.g. Ogaki dam lake lake water 0.12 Bq/L bottom sediment surface 200 kBq/kg

Peak concentration was observed from several to several tens cm depth in the lake deposits.

Concentration of radioCs in the estuary sediment was lower than that of flood plain and river bed sediment.

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