Groundwater–Surface Water Interaction - Methods and Case

UFZ Centre for Environmental ResearchLeipzig-Hallein the Helmholtz Association

Groundwater–Surface Water Interaction –

Methods and Case Studies

Stephan M. WeiseUFZ-Department of Isotope Hydrology


Groundwater–Surface Water Interaction is a process relevant for ...

• Salinisation of fresh groundwater due to sea water intrusion

• Intrusion of contaminated groundwatersinto surface water

• Developement of pit lakes highly contami-nated and acidified by lignite mining

• Groundwater un-covered by gravelproduction


1. Sea water intrusion• Problem:

Over-exploitation of costal-near groundwaterreservoirs causes intrusion of sea water

• Measures:Accurate ascertainment of the groundwaterreservoir to avoid over-exploitation

• Tools:- Monitoring of hydrochemical evolution- Definition of size of reservoir withenvironmental isotopes


1. Sea water intrusion

areas of investigation


1 Tools

•• StableStable isotopesisotopes ((22H, H, 1818O) of O) of waterwater →→Information Information aboutabout thethe originorigin of of waterwater

•• Tritium (Tritium (33H) of H) of waterwater and and 33He of He of dissolveddissolvedgasesgases →→ Information Information aboutabout thethe residenceresidencetime of time of waterwater

•• Noble gas Noble gas temperaturetemperature →→ DistinctionDistinctionbetweenbetween seasea and juvenile and juvenile waterswaters

……studystudy in in progressprogress……


2 Contaminated groundwater• Problem:

Groundwater highly contaminated with heavymetals infiltrates into surface water(inverse to river bank filtration)

• Measures:Under discussion yet, but at firstDetermination of the flow system as basis of further steps

• Tools:Hydrochemical monitoringDetection of inflow by temperature


StudyStudy SiteSite

0 25 50 kmC.Schmidt et al. 2006

C. Schmidt et al. (2006):Characterization of spatial heterogeneity of groundwater-streamwater interactions using multiple depth streambed temperature measurements at the reachScale. Hydrol. Earth Syst. Sci. Discuss., 3, 1419–1446


ConceptConcept

High Groundwater DischargeHigh Groundwater Discharge

Medium GroundwaterMedium Groundwater

Low Groundwater DischargeLow Groundwater Discharge

DischargeDischarge

Vertical Flow can be obtained from a simple one-dimensionalanalytical solution of the heat diffusion advection equation


MeasurementsMeasurements

Temperature in °C

12 14 16 18 20

Assumption: Observed streambed temperatures representspatial differences of groundwater dischargeAssumption: Observed streambed temperatures representspatial differences of groundwater discharge

Streambed temperatures are measured by temporarelyinserting a probe into streambed

Streambed temperatures are measured by temporarelyinserting a probe into streambed


ResultsResults

Stream

Streambed

Flow direction

Temperature in °C

12 14 16 18 20

Distance 220m

0.1m

0.5m

depth

Zones of high groundwater discharge


ResultsResults

Temperature profil can be converted to a water-influx profil


3 Mining lakes

• Problem:Flooding of holes from lignite mining activity are acidified(down to pH = 2) and contaminated with heavy metals

• Measures:Development of remediation strategies dependent on groundwater-lake water interaction

• Tools:- Inflow/outflow balance with environmental isotopes- Detection of inflow by 222Rn and stable isotopes- Governing biogeochemical cycles at benthos

RL-117

RL-111

RL-107

Lignite mine district Koyne-Plessa

Mining Lake RL 111


3 Test site RL 111Quartär

Grundwasserfließrichtung

angeschnittene TertiärsedimenteFörderbrückenkippeQuartärhaldeKippenböschung

200m0

N

ML

111

Germany

Leipzig

S-D

Messstelle

Probenahme-ort See

QuelleS

S-Q

D1

A1

D2

D3

D4

D5D6

A2

A3

A4

A5

crosssection

Braunkohle

Grundgebirge

GWL

Messstelle

Mixo-limnion

Monimolimnion

Restloch 111

Kippe

Length 900 mWidth 180 mDepth 10 m Area 110.000 m2


3 Determination of fluxes

Millimeter scale

micro sensors

O2

concentration

∆c∆x

high-resolution concentration profiles

(R. Stellmacher 2006)


RL 111:micro senors

Groundwaterflow direction

0

10

20

30

40

50

60

70

0 0.1 0.2 0.3 0.4

Konzentration [mmol/L]

Posi

tion

[mm

]

0

10

20

30

40

50

60

70

0 0.1 0.2 0.3 0.4


Posi

tion

[mm

]

0

10

20

30

40

50

60

70

0 0.1 0.2 0.3 0.4


Posi

tion

[mm

]

Position of sensors

ExfiltrationFM_NB1

1.5m depth

GW-neutralFM_NB2

7.0m depth

InfiltrationFM_SB1

1.5m depth


sediment-water interface


3 Determination of fluxesIn situ sediment incubation

Benthic Chamber

Change of concentration

with time

matter flux

”direct“ flux determination with simulated flow

provides information aboutfluxes and

biogeochemical processes


3 Determination of fluxes

Decimeter scale

DET (Gel Peeper)

front

view

side

view

diffusive equilibrium

high-resolution concentration profiles


Dialysis pore water sampler (DPS)


Position of DPSGroundwaterflow direction

RL 111:DP sampler

-60

-50

-40

-30

-20

-10

0

10

-10,0 -8,0 -6,0 -4,0 -2,0 0,0

δ18O-H2O (‰ VSMOW)

dist

ance

from

sed

./wat

er in

terfa

ce (c

m)

S-Südbecken 0.5m

S-Südbecken 2.5m

-60

-50

-40

-30

-20

-10

0

10

-10,0 -8,0 -6,0 -4,0 -2,0 0,0

δ18O-H2O (‰ VSMOW)

dist

ance

from

sed

./wat

er in

terfa

ce (c

m)

W-Südbecken 0.5m

W-Südbecken 2.5m

Monimolimnion

stagnantlittle inflow

high inflow

nothingis perfect!

(K. Knöller and S. Weise 2006)

The approach for quantifying The approach for quantifying gwgw discharge is a discharge is a steadysteady--state system with a consideration of all state system with a consideration of all

222222Rn sources and sinks related to the lake.Rn sources and sinks related to the lake.

RadonRadon is a naturally occurringis a naturally occurring radioactive radioactive gas, with a nongas, with a non--reactive nature and a short reactive nature and a short

halfhalf--life (tlife (t1/2 1/2 = 3.83 d)= 3.83 d)

RadonRadon is an excellent tracer to identify and is an excellent tracer to identify and quantify significant groundwater discharge.quantify significant groundwater discharge.

RadonRadon concentrations of groundwater are concentrations of groundwater are very large enriched to surface water very large enriched to surface water

(often 1000(often 1000--fold or more) fold or more)

Using Using 222222Rn to detect groundwater inflow into a lakeRn to detect groundwater inflow into a lake

gwgw--dischargedischarge[cm d[cm d--11]]

Total Total RadonfluxRadonflux[Bq/m²·d][Bq/m²·d]

(lake)

InventoryInventory[Bq m[Bq m--²²]]

(atmosphere)Fluxatm

(groundwater)

diffusiondiffusion, , otherother processesprocesses

(Axel Schmidt, UFZ, (Axel Schmidt, UFZ, DeptDept. . AnalyticalAnalytical ChemistryChemistry))

Diffusion cell foron-site Rn analytik

○○ area: 125,000 marea: 125,000 m²², medium depth: ~3 m, medium depth: ~3 m○○ pH = 2.4; FepH = 2.4; Fe = 400= 400--840 mg/l; SO840 mg/l; SO44

22-- = 1.8= 1.8--3.7 3.7 g/lg/l

Example: Example: TagebaurestlochTagebaurestloch RL 107, RL 107, PlessaPlessa

GroundwaterGroundwater dischargedischarge: :

0.182 0.182 ± 0.057 cm d± 0.057 cm d--11

gwgw--dischargedischarge[cm d[cm d--11]]

Total Total RadonfluxRadonflux[Bq/m²·d][Bq/m²·d]

(lake)

InventoryInventory[Bq m[Bq m--²²]]

(atmosphere)Fluxatm

(groundwater)

diffusiondiffusion, , otherother processesprocesses

FluxFluxatmatm = 2 ± 0.16 [= 2 ± 0.16 [BqBq mm--33]]Inventory = 75 ± 1.8 Inventory = 75 ± 1.8 [[BqBq mm--²²] ] DiffusionDiffusion = 0.2 = 0.2 [[BqBq mm--33]]RadonfluxRadonflux = 414 ± 9.9 = 414 ± 9.9 [Bq/m²·d][Bq/m²·d]

DataData::

Radon is a excellent tracer to Radon is a excellent tracer to quantify groundwater dischargequantify groundwater discharge

Using Using 222222Rn to detect groundwater inflow into a lakeRn to detect groundwater inflow into a lake

(Axel Schmidt, UFZ, (Axel Schmidt, UFZ, DeptDept. . AnalyticalAnalytical ChemistryChemistry))


RL 111: Isotopic balance

annual groundwater inflow: 23700m3

annual groundwater outflow: 15700m3

annual groundwater inflow: 23700m3

annual groundwater outflow: 15700m3

Basic input:

- annual variation in isotopiccomposition of lake water

- isotopic composition andamout of precipitation

- isotopic composition of groundwater

- surface in- and output

- (estimates of) evaporation

Basic input:

- annual variation in isotopiccomposition of lake water

- isotopic composition andamout of precipitation

- isotopic composition of groundwater

- surface in- and output

- (estimates of) evaporation

(K. Knöller 2001)

1

10

100

1000

10000pH 2.57

NE-SEE

1

10

100

1000

10000pH 2.58

RL111-0m

1

10

100

1000

10000pH 3.55

BZL111-1

1

10

100

1000

10000pH 3.05

BZL111-2

ground- and lake water chemistry

of the ML111 area

Feges

Cl-SO4

2-

K+

Mg2+

Ca2 +

Al3+ [mg/l]

pH 4.08

P-111-41

10

100

1000

10000

pH 5.17

P-111-11

10

100

1000

10000

pH 4.18

P-111-21

10

100

1000

10000

pH 5.01

P-111-31

10

100

1000

10000

pH 4.20

P-111-61

10

100

1000

10000

P-111-51

10

100

1000

10000pH 4.19

RL 111: Ground- and dump water(isotope-) geochemistry

N

N

N

N

N

N

+23,140

+6,01050 +5,6

900+0,5390

+32,0320

-4,8460

+18,53500

+8,24300

+3,8320

+21,0100

δ34S ‰ CDTSO (mg/l)4

δ34S ‰ CDTSO (mg/l)4

sampling wellsaquifersampling wellsdump

outflow oflake water

into aquifer

inflow aquiferinflow dump

+7,02200

-9,9700

Mining

Lake

111

sampling pointlake water+3...+5 1100...2000 mg/l

‰

SO4 vary between 40 and 700 mg/L in the aquifers

SO4 reaches 4300 mg/L at max. in dump water

δ34S: –9.9 to +23 %o in GW

δ34S: +7 and +32%o in dump water


RL 111: Results of isotopegeochemical investigations

• Sulfat from mining dumps is reduced in theaquifer west of RL 111.

• In the dump, oxidation of pyrite and mobilisation still provides a permanent sulphate input into the lake.

• Consequently, for remediation measuresthe groundwater inflow from dumps haveto be taken into account


Mining lakes: Perspective…from mining landscape…

…to recreation landscape

Cospuden mining area(south of Leipzig)


4 4 GravelGravel productionproduction

• dis-covers high-productive aquifers and• connects a groundwater flow system with

lake water.Issues:• What is the intensity of groundwater-lake

connection?• What is the effect on groundwater quality?


V20Hori V19

V6V7

DP11

DP10

DP9

Germany

Studyarea

Groundwaterflow direction

115

116

LakeLeis

117

118

120

121

119

117.3

groundwatertable [asl]

Well investigatedfor H content3

4 Case study Lake LeisLake Leis:

Surface area: 116,000 m2

Depth: 21 m (in average)annual turnover

Aquifer:

Geology: Quaternary gravel and sandsGroundwater flow velocity: 0.5 – 2 m/d

(S. Weise, W. Stichler, B. Bertleff 2001)


4 Lake Leis: Tritium ”age“

1

10

100

1000

0 10 20 30 40 50

Years before date of sampling

Triti

umco

nte n

t[ T

U]

H range of deeper ground-3

and Lake Leis waters

Apparentage

3H in precipitationcorrected for

decay


4 Lake Leis: 3He/3H ”age“

“age” of about 20 years

though the lake turns over every year

exchange with atmosphere (degassing)

resets 3He/3H “age” close to zero

Lake Leis16.10.1997

0

5

10

15

20

250 5 10 15 20 25 30

apparent 3He/3H age [years]

Dep

th[m

]

Stagnationzone

Circulationzone Range of

apparentH ages3


4 Case study Lake Leis

Results from 3He/3H investigations:• groundwater inflow is about 2000 m3/d.• regarding known hydraulic conductivities,

the area effective for inflow is between 500 and 7500 m2, consistent with lake's cross-section area of about 6000 m2.

• Lake Leis must be extremely good incorporated into the regional ground water flow regime.


Mining lakes Merseburg Ost

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Groundwater–Surface Water Interaction - Methods and Case