yarko niño department of civil engineer ing , universidad de chile

Yarko NiñoDepartment of Civil Engineering, Universidad de Chile

THE WATER ENVIRONMENT AND HUMAN NEEDS:

Ingeniería Civil

A CASE STUDY INVOLVING THE HYDRODYNAMICS OF A COASTAL LAKE IN SOUTHERN CHILE

… THIS WIDER SCOPE OF APPROACHING FUTURE PROBLEMS OF THE WATER ENVIRONMENT … WHEN ALL THE COMPLEX

ENVIRONMENTAL AND SOCIAL FACTORS MUST BE CONSIDERED IN A GIVEN SYSTEM TO MEET THEM WITH CREATIVE IDEAS AND

TECHNOLOGY AT PRESENT STILL LARGELY UNKNOWN …

(A.T. IPPEN, 1970)

THE WATER ENVIRONMENT AND HUMAN NEEDS

THE PLAN

EXPLORE A SYSTEM WHOSE HYDRODYNAMICS HAS A STRONG IMPACT ON THE ENVIRONMENT AND WELL-BEING OF LOCAL COMMUNITIES

IN THE PROCESS DISCUSS ASPECTS OF TRANSPORT AND MIXING IN STRATIFIED FLOWS

GO FROM THEORY TO PRACTICE (THROUGH EXPERIMENTS AND NUMERICAL MODELING)

THE SYSTEM

RIVER AND LAKE BUDI

38º 52` 73º 22`

BUDI RIVER

MOUTH

LAKE BUDI

THE SYSTEM

15 km

THE SYSTEM

2826242220181614

0

8

4

DISTANCE (km)

DE

PTH

(m)

DISSOLVED OXYGEN (mg/l)

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0

8

4

DE

PTH

(m)

DISTANCE (km)

SALINITY (pss)

SALINITY STRATIFICATION AND DISSOLVED OXYGEN

THE SYSTEM

BUDI RIVER MOUTH (ICOL)

THE SYSTEM

ARTIFICIAL OPENING

SOCIAL AND ENVIRONMENTAL ISSUES

LAKE BUDI IS LOCATED IN A REGION OF LOW-INCOME RURAL NATIVE PEOPLE (MAPUCHE) COMMUNITIES

MAIN ECONOMIC ACTIVITIES ARE SMALL-SCALE FISHING AND AGRICULTURE

IN RECENT YEARS FISHING IN THE LAKE HAS DECLINED FORCING LAND-USE CHANGES FOR AGRICULTURE

THIS HAS FORCED EARLIER IN THE YEAR AND MORE FREQUENT OPENINGS OF THE MOUTH BAR AND DECAYING WATER QUALITY IN THE LAKE

RIVER AND LAKE SALINITY INTRUSION DYNAMICS

FIELD OBSERVATIONS 2006-2007

2 MOUTH-BAR OPENINGS IN THE AUSTRAL WINTER OF 2006: JUNE 22 AND OCTOBER 5

OCTOBER 2 (3 DAYS PRIOR 2ND OPENING )

OCTOBER 18 (2 WEEKS AFTER 2ND OPENING )

DECEMBER 12 (10 WEEKS AFTER 2ND OPENING )

JANUARY 29 (17 WEEKS AFTER 2ND OPENING )


SALINITY STRUCTURE PRIOR 2ND OPENING

OCTOBER 2

DISTANCE (km)

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28

8

6

4

2

0

Z (m)

SALINITY (pss)1816141210864


SALINITY STRUCTURE 2WEEKS POST 2ND OPENING

OCTOBER 18

DISTANCE (km)


0 2 4 6 8 10 12 14 16 18 20 22 24 26 28

8

6

4

2

0

Z (m)


SALINITY STRUCTURE 10 WEEKS POST 2ND OPENING

DECEMBER 18

DISTANCE (km)


0 2 4 6 8 10 12 14 16 18 20 22 24 26 28

8

6

4

2

0

Z (m)


0 2 4 6 8 10 12 14 16 18 20 22 24 26 28

8

6

4

2

0

COMPLETE MIXING!

SALINITY STRUCTURE 17 WEEKS POST 2ND OPENING

JANUARY 29

DISTANCE (km)

Z (m)



SALINITY INTRUSION: PLUNGING AND DENSITY CURRENT


Qii

ah

PLUNGING POINT

U


Qii

ah

PLUNGING POINT

U

ELLISON & TURNER (1959)


DENSITY CURRENT IN THE LAKE (2 WEEKS POST 2ND OPENING)

DISTANCE (km)

5 10 15 20 25

Z (m)

FREE SURFACE

DENSITY CURRENT

FIELD OBSERVATIONS

-120

-100

-80

-60

-40

-20

0

20

40

10/1/06 10/8/06 10/15/06 10/22/06 10/29/06 11/5/06


EXCHANGE FLOWS

Q (m3/s)

DAILY MEAN FLOW RATES

DATE

SALINITY (PSS)

FRESH INFLOW

SALTY INFLOW

OUTFLOW

MIXING IN STRATIFIED FLUID


WIND MIXING IN TWO-LAYER FLUID

h1

h2

1

2

u*

WIND RICHARDSON NUMBER


EXPERIMENTS (NIÑO ET AL., 2003)

t = 0

t = 3 min

t = 15 min

t = 50 min

t = 120 min

DENSITY MAPS, Ri* = 82.6

ENTRAINMENT VELOCITY


EXPERIMENTS (NIÑO ET AL., 2003)

(KRANENBURG, 1985; MONISMITH, 1986)

0.00001

0.0001

0.001

0.01

0.1

1 10 100 1000 10000

Series 1 (L/H = 9)Series 2 (L/H = 6)Series 3 (L/H = 9)Kranenburg (L/H = 74)Kranenburg (L/H = 26)

ue/u*

Ri*


LET’S DO SOME THEORY IPPEN’S STYLE (e.g., HARLEMAN & IPPEN, 1966)


FRICTION FACTOR

GAIN IN PE

WIND INPUT

BULK MIXING EFFICIENCY(TSENG & FERZIGER, 1998)

(0.2%)


LET’S TRY A DIFFERENT APPROACH!


MIXING EFFICIENCY

TKE BALANCE

TURBULENT DIFFUSIVITY

0.15 (WÜEST & LORKE, 2003)

h1

h2

S1

S2

u*


VALUE?


0

0.2

0.4

0.6

0.8

1

-0.2 0.0 0.2 0.4 0.6 0.8 1.0

z/H

u/us

0

0.2

0.4

0.6

0.8

1

0 0.005 0.01 0.015

z/H

K/us2

K- MODEL WITH BUOYANCY EFFECTS

VELOCITY

TKE


K- MODEL WITH BUOYANCY EFFECTS

0

0.2

0.4

0.6

0.8

1

-0.2 0.2 0.6 1.0 1.4 1.8 2.2

z/H

u/us

MIXING IN LAKE BUDI

MIXING IN LAKE BUDI


0

0.2

0.4

0.6

0.8

1

0 5 10 15 20

OCTOBER 18DECEMBER 12JANUARY 29z/H

S (pss)

MIXING IN LAKE BUDI


WIND VELOCITY

(m/s)

ue/u* 210-5 Ri* 2.2104

MIXING IN LAKE BUDI

0.000001

0.00001

0.0001

0.001

0.01

0.1

1 10 100 1000 10000 100000

Series 1 (L/H = 9)Series 2 (L/H = 6)Series 3 (L/H = 9)Kranenburg (L/H = 74)Kranenburg (L/H = 26)LAKE BUDI

ue/u*

Ri*

MIXING IN LAKE BUDI

MIXING DUE TO BENTHIC BOUNDARY LAYER TURBULENCE

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0

8

4

DISTANCE (km)

DE

PTH

(m)

SIMULATION OF LAKE BUDI HYDRODYNAMICS

SALINITY (pss)

MODELING SALINITY INTRUSION AND MIXING

OPEN


DISSOLVED OXYGEN CONCENTRATION (mg/l)

MODELING DISSOLVED OXYGEN CONCENTRATION

OPEN


PREDICTION IN THE CASE OF NATURAL MOUTH BAR OPENING

DISSOLVED OXYGEN CONCENTRATIONDENSITY (kg/m3)

OPEN OPEN


FINAL REMARKS

PRESENT MOUTH BAR MANAGEMENT WOULD NOT BE COMPATIBLE WITH FISH ECOLOGICAL DYNAMICS

BETTER PRACTICE MUST COMPATIBILIZE FLOODING PROTECTION, WATER QUALITY, LAKE ECOLOGY, AND LOCAL COMMUNITIES WELFARE

RESEARCH IS FUN BUT IS MORE FUN WHEN IT IS PUT AT THE SERVICE OF PROTECTING AND IMPROVING SOCIAL AND ENVIRONMENTAL CONDITIONS

THANKS TO:

FELIPE SANDOVAL CLAUDIA RODRIGUEZMANUEL CONTRERAS

MIXING IN LAKE BUDI

TURBULENT INTENSITY PARAMETER (IVEY ET AL., 2008)

I ≈ 0.15

Re* ≈ 3104

Ri* ≈ 2104

Li/h1 ≈ 0.2

LAKE BUDI

WUEST & LORKE (2005): I ≈ O(1) AT LAKES THERMOCLINE

EXPERIMENTS NIÑO ET AL. (2003): I ≈ 1-15

MIXING IN LAKE BUDI

TURBULENT INTENSITY PARAMETER (IVEY ET AL., 2008)

MIXING DUE TO BENTHIC BOUNDARY LAYER TURBULENCE

I < 77< I < 100

I > 100

MOLECULARTRANSITIONAL

ENERGETIC

REGIMEI RANGE

CHECK!

yarko niño department of civil engineer ing , universidad de chile

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