Water Level Variation Due to Hydrologic … Level Variation Due to Hydrologic Connections in a...

Water Level Variation Due to Hydrologic Connections in a Coastal Salt Marsh: The Case of El Yali Coastal Lagoon, Chile

Pablo GaldamesChi-Le Sun

Alejandro Dussaillant

PASEO 2009Bahía Blanca, Argentina

March 17, 2009

AcknowledgementsDr. José M. Farina ecosystem ecology group (PUC-CASEB), for field & ecological support, & ongoing fruitful collaboration!Chilean Forestry Service – CONAF, V Región (Alvaro Damico & others), for access and field support.Navy oceanography service, SHOA; Chilean Water Agency, DGA (Eric Weidenslaufer); Meteorology agency, DMCh (Jorge Carrasco), for kindly handing data.Drs. Scott Tyler (U. Nevada, USA), Aaron Packman (Northwestern U., USA), Eric Barthélemy (U. Grenoble, France) for encouraging field discussions!F. Varas, J. Aravena, R. Galdames & many others for being so cheerful field aides.

Coastal Lagoons & Salt MarshesDynamic – frequent fluctuations (due to tide, meteorology, winds, salinity, temperature).Vegetation stabilizes dunes, promote deposition.Zonation partly due to salinity & flooding gradients.Productivity & range correlated with water level, but unproven connection (beyond doubt).Nutrient fluxes also depend strongly on hydro-fluctuations.Few studies, in Mediterranean lagoons and salt marshes, on water level spatial and temporal variations. Sapelo Island, Georgia, USA

MotivationIntertidal environments are dynamic and vulnerable, affected by climate change and human pressure (Ursinoet. al, 2004)Strong relationships between hydrology, physical-chemical links and biota (Mitsch and Gosselink, 2000) Changes in water levels affects plant zonation and with this, the whole environment (Krasnosteinand Oldham, 2004)Few studies in Chilean wetlandsYali Ramsar site under pressure: agric + tourism

Yali Ramsar wetland

(Source: www.sinia.cl)

General backgroundLocated in the central zone of ChileAprox. area: 750 Km2

Coastal watershed fully pluvial:

P: 468 mm (annual mean)ETp: 600 mm (annual mean)

Yali stream:50 km lengthFlow annual mean approx 1.5 m3/sSource: CS 2007, adapted from MOP, 2005

El Yali site: unique (yet template?)Unique coexistence of halophyte (Northern Chile) & palustrian(Southern Chile) vegetation.

25-40% of Chilean native bird diversity hotspot (> 115 spp.).

General project objectivesTo know the hydrologic budget of the lagoon:

Gathering of meteorological dataSurface flows through stream and ditchesSubsurface flows (groundwater and sea)Surfacewater connection with the sea

To characterize the fluxes of:

HeatSalinityNutrients

SEA

LAGOON

SEALAGOON

QOM

PE

QS

QE

QSM QGM

QD

EQQQQQQPtS

SSMGMOMDE −±±±+++=ΔΔ

El Yali stream, and outlet (open/closed)

Stream, 2 km upstream of outlet

Outlet – closed

Outlet – open to the sea

MethodologyIdentification and characterization of groundwater flows

Piezometer installationLevel recording + sampling

Transect topography

SEA

LAGOON CO3

CP1 CO1CO2

CP3CP4CP5 CP2

MethodologyIdentification and characterization of groundwater flows (cont.)

Soil hydraulic propertiesContinued water level recording with pressure transducersAnalysis of seasonal and tidal effect in levels

Seepage meter:

Results

Gathered information:Scarce available meteorological information

Santo Domingo aerodrome (hourly wind)Meteorological station Fundo Las Dos Puertas (rainfall data since 1990)

Hourly tidal records (San Antonio)Tidal amplitude ~1m (micro-tidal)

Detailed topography of transects and ditches (2005-2006)Local cartography and hydrologic information

Estac ión Fundo Las Dos Puertas

0100200300400500600700800900

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

Prec

ipita

ción

(mm

)

ResultsWater levels identification

Summer (dry) situation: disconnectionScarce variation on lagoon water level (<10 cm)Lagoon-sea dune groundwater level affected by wavesRainfall events do not affect lagoon level (LO)

LO: Lagoon at eastern side

97.5

98.0

98.5

99.0

99.5

100.0

02/02/2006 07/02/2006 12/02/2006 17/02/2006 22/02/2006 27/02/2006

Altu

ra re

lativ

a (m

) SO1

LO

CP2

CP3

CP5

Mar

Rel

ativ

e he

ight

(m

)

Sea

February 2006

ResultsWater levels identification (cont.)

Winter (wet) situation: connectionStrong daily variation in lagoon levels

Rises 8 to 80 cm (average 23,3 cm) in approx. 4 hoursCycles of 14 hours as typical period

97.5

98.0

98.5

99.0

99.5

100.0

01/08/2006 06/08/2006 11/08/2006 16/08/2006 21/08/2006 26/08/2006 31/08/2006

Altu

ra re

lativ

a (m

)

0

50

100

150

200

250

Prec

ipita

cion

es (m

m) Pp

SO1

LO

CP2

CP5

Mar

Rel

ativ

e he

ight

(m

)

Sea

Prec

ipitat

ions

(m

m)

August 2006


Processes in connected stage:Strong precipitation event causes the sea-lagoon connectionSurface flow from ocean

Depends on Moon phase: tidesLagoon rising rate: ~10 cm/hrDescent rate: ~2 cm/hr (initial fast surface flow phase + slow groundwater flow from lagoon)

WindAffects levels only during high tidesCorrelation with water levels is not detected


Disconnection mechanismProgressive sedimentation and stabilization of sand bar at stream mouthProcess took around 10 days in 2006

97.5

98.0

98.5

99.0

99.5

01/09/2006 06/09/2006 11/09/2006 16/09/2006 21/09/2006 26/09/2006 01/10/2006

Altu

ra re

lativ

a (m

) SO1

LO

CP2

CP3

CP5

Mar

Rel

ativ

e he

ight

(m

)

Sea

September 2006


Summer spectrum1st peak: series length2nd peak: 23,93 hrs

Winter spectrum1st peak: 16,44 days2nd peak: 24,16 hours3rd peak: 12,46 hours4th peak: 8,22 hours5th peak: 6,20 hours

f [cycles/timeunit]

Spec

trum

Spectrum Annual Series (original)

0 0.1 0.2 0.3 0.4 0.5

0

50

100

150

200

250

300

f [cycles/timeunit]

Spec

trum

Spectrum Annual Series (original)

0 0.1 0.2 0.3 0.4 0.5

0

10

20

30

40

50

60

Lunar phase

Tides

Daily cicles

Sea - Lagoon water level relationship:a preliminary analysis

Signal Analysis - FFT and Pattern of Residuals:

98.6098.65

98.7098.75

98.8098.85

98.9098.95

00:00 03:00 06:00 09:00 12:00 15:00 18:00 21:00 00:00 03:00

Time (hours)

Rel

ativ

e he

ight

(m)

98,6

98,7

98,8

98,9

99

99,1

99,2

99,3

99,4

14-07 16-07 18-07 20-07 22-07 24-07 26-07 28-07 30-07

Time (hours)

Rel

ativ

e he

ight

(m)

Simulated

Real

Extracted pattern of lagoon periodical oscillations(Jun 10-Sep 15, 2006)

Fourier analysis for lagoon level as function of sea level (Jul 13-Aug 31, 2006)


Interannual oscillation in lagoon’s water level

Year 2006

Rel

ati

ve h

eig

ht

(m)

Rel

ati

ve h

eig

ht

(m)

Disconnected

Connected

Connected

Disconnected

Connection

Disconnection


Interannual oscillation in lagoon’s water level & La Niña

Year 2007

Rel

ati

ve h

eig

ht

(m)

Rel

ati

ve h

eig

ht

(m)

Disconnected

Disconnected

Disconnected

Disconnected


Interannual oscillation in lagoon’s water level & end of La Niña in June 2008

Year 2008

Rel

ati

ve h

eig

ht

(m)

Disconnected

Connected

Connection

Nivel de la laguna (relativo a referencia)

98.298.498.698.8

9999.299.499.6

18/0

5/20

08

18/0

5/20

08

19/0

5/20

08

20/0

5/20

08

21/0

5/20

08

22/0

5/20

08

23/0

5/20

08

23/0

5/20

08

24/0

5/20

08

25/0

5/20

08

26/0

5/20

08

27/0

5/20

08

27/0

5/20

08

28/0

5/20

08

29/0

5/20

08

30/0

5/20

08

31/0

5/20

08

1/6/

2008

1/6/

2008

2/6/

2008

3/6/

2008

4/6/

2008

5/6/

2008

5/6/

2008

Fecha

m (s

obre

ref

.)Precipitación (estación en macrozona secano costero central)

02468

1012

18/0

5/20

08

18/0

5/20

08

19/0

5/20

08

20/0

5/20

08

21/0

5/20

08

22/0

5/20

08

23/0

5/20

08

24/0

5/20

08

25/0

5/20

08

25/0

5/20

08

26/0

5/20

08

27/0

5/20

08

28/0

5/20

08

29/0

5/20

08

30/0

5/20

08

31/0

5/20

08

1/6/

2008

1/6/

2008

2/6/

2008

3/6/

2008

4/6/

2008

5/6/

2008

6/6/

2008

Fecha

mm

RECONNECTION

1ST WEEKOF JUNE2008

before after

Sea storm


Statistical analysis of interannual data

Similar behaviourin mean, and minimum values, in spite of the absence of connection during winter of 2007Differences in std. deviation for different connected (C) and disconnected (D) phase

Rel

ati

ve h

eig

ht

(m)

Std

. D

evia

tio

n (

m)

C CD D DD D

C CD D DD D

Results – water temperature

Volver

Sea (MAR, below, in brown), lagoon (LO, above, in cyan) and transect piezometers in between (CP5 to CP2, from sea towards the lagoon)Distinct sea water temperature, relatively constant and slow trend

Lagoon water temp has higher values and fluctuations (shallow)

10.0

12.0

14.0

16.0

18.0

20.0

22.0

24.0

01-08-2006 16-08-2006 31-08-2006 15-09-2006 30-09-2006 15-10-2006 30-10-2006

Tem

pera

tura

(ºC

) SO1LOCP2CP3CP5MAR

ResultsWater bodies characterization (cont.)

Electric Conductivity profile

Salinity gradient inside the lagoon itselfEvidence of a salt wedge and a fresh water lens between lagoon and sea (at least seasonally)

0

20

40

60

80

100

120

Oriente 3 Oriente 2 Oriente 1 Laguna (O) Laguna (P) Poniente 1 Poniente 2 Poniente 3 Poniente 4 Poniente 5 Mar

Cond

uctiv

idad

elé

ctric

a (m

S/cm

)Ele

ctri

c co

nd

uct

iviy

(mS

/cm

)

East 3 East 2 East 1 Lagoon (E) Lagoon (W) West 1 West 2 West 3 West 4 West 5 Sea

Shallow groundwater level modeling –Dupuit assumption & diffusion equation

Preliminary approach: simple diffusive model, assuming horizontal subsurface flow in unconfined aquifer

paKD ·

=pw

xhD

th

=∂∂⋅−

∂∂

2

2

101,0

101,2

101,4

101,6

101,8

102,0

102,2

102,4

12-07 17-07 22-07 27-07 01-08 06-08 11-08 16-08 21-08 26-08 31-08

Rel

ativ

e he

ight

(m) model (Ks=1.7 x 10-4)

CP5

with h: water levelK: conductivityw: rainfall ratep: sand porosity

Dupuit model results for piezometer CP5 (sand bar between lagoon and sea)

(Ks~ 6 m/d)

DiscussionLagoon water level

Hierarchy: sea connectivity > tide > rainsIntermittently open estuary (mostly closed annually) – effect of increasing abstractions?Scour (streamflow & tide) vs. Blockage (onshore & longshore transport)

Analysis and ModelingIf connected: sea level controlsNumerical model: trends OK, but noisy

OtherFloods reset the system: flush the outlet barImplications for managers?

Future WorkMonitoring

Add 2 new piezometer transects + sensor/loggers.Distributed Temp. System for sea washover & outlet.Water and nutrient budgets (impacts? denitrification?).

Analysis and ModelingHarmonic analysis (extract astronomic forcings).Density-dependence model (e.g. SUTRA).

OtherVegetation zonation and water level fluctuations.Climate change & ENSO scenariosSedimentation/erosion processes.Compare to other similar systems (in Chile; abroad?).

Laguna de Conchalí (Pupío stream, IV), La Laguna (Maitencillo, V), Tunquén (Casablanca stream, V), El Tabo (V R), Laguna de los Cisnes (Cartagena stream, V R), Topocalma (Topocalma stream, VI R), Laguna Petrel (Pichilemu stream, VI R), Bucalemu (VI R), Boyeruca (VII R), Buchupureo (VIII R), ...

[ ]∑=

++=M

ppppp tfbtfahth

10 )2sin()2cos()( ππ

[ ]1s w h

pS P Qt t

ωφβ ρ ρρ μ

⎛ ⎞∂ ∂+ = ∇ ⋅ ⋅ ∇ − +⎜ ⎟∂ ∂ ⎝ ⎠

k g

Thank youfor your attention!

– questions?

Preliminary results – water quality

0

10

20

30

40

50

60

PozoOriente

Laguna(oriente)

Laguna(poniente)

PozoPoniente 1

PozoPoniente 2

PozoPoniente 3

PozoPoniente 4

PozoPoniente 5

Mar

Salin

idad

(o/o

o)

PO43- decreases towards sea (upland ground & surface water ~1

mg/L; lagoon ~0.3 mg/L; while ocean ~ 0.1 mg/L).

NO3: unclear spatial & temporal trends (limiting nutrient).

DO (& pH) higher in lagoon than surrounding groundwater.

Salinity maximum for lagoon ~50‰ in summer dry period.

Minimum groundwater salinity registered 6.6‰ (60m upslope).

Freshwater underflow to sea-lagoon groundwater?:

Preliminary results – phosphatePO4

3- : decreases from upslope to lagoon to sea

upland ground & surface water ~1.2 mg/L

lagoon ~0.3 mg/L (similar to seaside piezometers)

while ocean ~ 0.1 mg/L.

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

CO3 CO2 CO1 LO LP CP1 CP2 CP3 CP4 CP5 MAR

P-P

O4

(mg/

L)

Preliminary results – nitrateNO3:

unclear spatial & temporal trends

limiting nutrient

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4


N-N

O3

(mg/

L)

Preliminary results – salinity & EC

0

10

20

30

40

50

60

PozoOriente

Laguna(oriente)

Laguna(poniente)

PozoPoniente 1

PozoPoniente 2

PozoPoniente 3

PozoPoniente 4

PozoPoniente 5

Mar

Salin

idad

(o/o

o)

Minimum groundwater salinity registered 6.6‰ (60m upslope from lagoon).

Salinity maximum for lagoon ~50‰ in summer dry period.

Salinity gradients in lagoon.

Shallow groundwater between lagoon & sea with lower S & EC -freshwater underflow from upslope aquifer?

0

20

40

60

80

100

120


Cond

uctiv

idad

elé

ctri

ca (m

S/c

m)

ResultsWater bodies characterization

TemperatureSummer

Average near 24 ºC (over sea mean temp.)High daily oscillation (~10 ºC)

12.0

16.0

20.0

24.0

28.0

32.0

15/01/2006 25/01/2006 04/02/2006 14/02/2006 24/02/2006 06/03/2006 16/03/2006

Tem

pera

tura

(ºC

) SO1

LO

CP2

CP3

CP5

MAR

Tem

pera

ture

(ºC

)

Sea


Temperature (cont.)Winter

Lower daily oscillationRainfall events affect groundwater temp.

7.0

10.0

13.0

16.0

19.0

22.0

13/05/2006 23/05/2006 02/06/2006 12/06/2006 22/06/2006 02/07/2006 12/07/2006 22/07/2006 01/08/2006

Tem

pera

tura

(ºC

)

0

50

100

150

200

250

13/05/2006 23/05/2006 02/06/2006 12/06/2006 22/06/2006 02/07/2006 12/07/2006 22/07/2006

Prec

ipita

cion

es (m

m) Pp

SO1

LO

CP2

CP3

CP5

MAR

Tem

pera

ture

(ºC

)

SeaPrec

ipitat

ions

(m

m)


Temperature (cont.)Disconnection

Progressive increase in Tº in all water bodiesSeparation between sea and lagoon Tº

10.0

12.0

14.0

16.0

18.0

20.0

22.0

24.0

01/08/2006 16/08/2006 31/08/2006 15/09/2006 30/09/2006 15/10/2006 30/10/2006

Tem

pera

tura

(ºC

) SO1LOCP2CP3CP5MAR

Tem

pera

ture

(ºC

)

Sea

References

Krasnostein A.L., and Oldham C.E. (2004) Predicting wetland water storage, Water Resour. Res., 40, W10203Leiva I., Meza J., Möder L. (1995) Fundamento para la creación de la Reserva Nacional El Yali. DocumentoelectrónicoMitsch W.J., Gosselink J.G. (2000) Wetlands. 3º Edición. Ed. John Wiley & Sons, EEUUMOP (2005) Area de restricción sector hidrogeológico de aprovechamiento común de Yali bajo El Prado. DocumentoelectrónicoMOP (2005) Determinación de la disponibilidad de derechos de aprovechamiento de aguas subterráneas en la cuenca del Estero Yali hasta sector El Prado, RegiónMetropolitana. Documento electrónicoUrsino N., Silvestri S., Marani M. (2004) Subsurface flow and vegetation patterns in tidal environments. Water Resour. Res., 40, W05115

Annexes

Characterization per transectElectric conductivityNitratePhosphate

Explicit finite difference modelSalinity effect

Electric conductivity

0

20

40

60

80

100

120

NO3 NO2 NO1 LO LP NP1 NP2 NP3 NP4 MAR

Con

duct

ivid

ad e

léct

rica

(mS

/cm

)

0

20

40

60

80

100

120


Cond

uctiv

idad

elé

ctric

a (m

S/cm

)

Back

0

20

40

60

80

100

120

SO3 SO2 SO1 LO LP SP1 SP2 MAR

Cond

uctiv

idad

elé

ctric

a (m

S/cm

)

Nitrate

0.0

0.5

1.0

1.5

2.0

2.5

3.0


N-N

O3

(mg/

L)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4


N-NO

3 (m

g/L)

Back

0.0

0.5

1.0

1.5

2.0

2.5

3.0


N-N

O3

(mg/

L)

Phosphate

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0


P-PO

4 (m

g/L)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8


P-PO

4 (m

g/L)

Back

0.0

1.0

2.0

3.0

4.0

5.0

6.0


P-PO

4 (m

g/L)

Explicit finite difference model

98.6

98.7

98.8

98.9

99.0

99.1

12/07/2006 22/07/2006 01/08/2006 11/08/2006 21/08/2006 31/08/2006

33 m

CP2

22 m

98.2

98.4

98.6

98.8

99.0

99.2

99.4

99.6

12/07/2006 22/07/2006 01/08/2006 11/08/2006 21/08/2006 31/08/2006

99 m

CP5

88 m

Back

KS=6,21·10-5 m/s; n=0,43; a=100 m λ=0,859

Salinity effect

Border conditions equivalents for fresh water

99

99.5

100

100.5

101

101.5

102

102.5

12/07 17/07 22/07 27/07 01/08 06/08 11/08 16/08 21/08 26/08 31/08

Altu

ras

rela

tivas

tran

sfor

mad

as (m

)

5,77*10-56,64*10-56,205*10-5CP2

100

100.5

101

101.5

102

102.5

12/07 17/07 22/07 27/07 01/08 06/08 11/08 16/08 21/08 26/08 31/08

Altu

ras

rela

tivas

tran

sfor

mad

as (m

)

1,70*10-41,53*10-41,615*10-4CP5

Salinity effect (cont.)

100.8

101

101.2

101.4

101.6

101.8

102

102.2

102.4

12/07 17/07 22/07 27/07 01/08 06/08 11/08 16/08 21/08 26/08 31/08

Altu

ras

rela

tivas

tran

sfor

mad

as y

aj

usta

das

(m)

5,77*10-56,64*10-56,205*10-5CP2

101

101.2

101.4

101.6

101.8

102

102.2

102.4

12/07 17/07 22/07 27/07 01/08 06/08 11/08 16/08 21/08 26/08 31/08

Altu

ras

rela

tivas

tran

sfor

mad

as y

aj

usta

das

(m) 1,70*10-4

1,53*10-41,615*10-4CP5

Eliminating differences in mean value

Back

“El Yali”Complex including salt marsh in one of the 9 Ramsar site in ChileNational Reserve covers 520 Ha close to Santo Domingo beach, V RegiónHabitat for about 25% of the chilean bird biodiversityConsidered the most important coastal wetland in central-north of Chile (Leiva et al., 1995)

Source: www.mop.gov.cl

Results (cont.)

KS (fields + laboratory + empiric formula)5,77·10-5 m/s eastern side6,64·10-5 m/s western side

Kbottom (seepage)1,08·10-7 m/s

Hydrogeological watershed informationFree aquifer of ~ 100 m depht at river mouthTransmisivity from 1000 to 2000 m2/d Storage coefficient 0,1


Processes in disconnected stage:Rainfall events

Quick rise of groundwater levels (sandy soil)Little effect in lagoon (damped)

WindSea rising induce a rising wave in groundwaterWind direction induced differential lagoon rise toward the extreme or inner of the channel. Wind intensity-lagoon level correlation (quadrant 225º-315º):

Positive values mean: 0.716


Nutrients profiles

0,0

0,2

0,40,6

0,8

1,0

1,21,4

1,6

1,8


P-PO

4 (m

g/L)

0,0

0,2

0,4

0,6

0,8

1,0

1,2

1,4


N-N

O3

(mg/

L)




6,0

6,5

7,0

7,5

8,0

8,5

9,0

9,5


pH

Dissolved oxygen profile

pH profile

0

2

4

6

8

10

12

14


OD

(mg/

L)



Modelling

Implicit finite difference model

paKD ·

=pw

xhD

th

=∂∂⋅−

∂∂

2

2

98.4

98.5

98.6

98.7

98.8

98.9

99

99.1

99.2

12/07 17/07 22/07 27/07 01/08 06/08 11/08 16/08 21/08 26/08 31/08

Altu

ras

rela

tivas

(m)

5,77*10-56,64*10-56,205*10-5CP2

98.4

98.6

98.8

99

99.2

99.4

99.6

99.8

12/07 17/07 22/07 27/07 01/08 06/08 11/08 16/08 21/08 26/08 31/08

Altu

ras

rela

tivas

(m)

1,70*10-41,53*10-41,615*10-4CP5

Rela

tive

heig

ht

(m)

Simulated flows for El Yali stream

0

50

100

150

200

250

300

01/01

/1992

19/07

/1992

04/02

/1993

23/08

/1993

11/03

/1994

27/09

/1994

15/04

/1995

01/11

/1995

19/05

/1996

05/12

/1996

23/06

/1997

09/01

/1998

28/07

/1998

13/02

/1999

01/09

/1999

19/03

/2000

05/10

/2000

23/04

/2001

09/11

/2001

28/05

/2002

14/12

/2002

02/07

/2003

18/01

/2004

05/08

/2004

21/02

/2005

09/09

/2005

Cau

dal d

iario

cal

cula

do (m

3 /s)

-10

40

90

140

190

240

290

Pre

cipi

taci

ón (m

m)

PrecipitaciónCaudal calculado

Water Level Variation Due to Hydrologic … Level Variation Due to Hydrologic Connections in a...

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