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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
PT
H (
m)
DISSOLVED OXYGEN (mg/l)
2826242220181614
0
8
4
DE
PT
H (
m)
DISTANCE (km)
SALINITY (pss)
SALINITY STRATIFICATION AND DISSOLVED OXYGEN
THE SYSTEM
BUDI RIVER MOUTH (ICOL)
THE SYSTEM
ARTIFICIAL OPENING
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 )
RIVER AND LAKE SALINITY INTRUSION DYNAMICS
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
RIVER AND LAKE SALINITY INTRUSION DYNAMICS
SALINITY STRUCTURE 2WEEKS POST 2ND OPENING
OCTOBER 18
DISTANCE (km)
SALINITY (pss)1816141210864
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28
8
6
4
2
0
Z (m)
RIVER AND LAKE SALINITY INTRUSION DYNAMICS
SALINITY STRUCTURE 10 WEEKS POST 2ND OPENING
DECEMBER 18
DISTANCE (km)
SALINITY (pss)1816141210864
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28
8
6
4
2
0
Z (m)
RIVER AND LAKE SALINITY INTRUSION DYNAMICS
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 (pss)1816141210864
RIVER AND LAKE SALINITY INTRUSION DYNAMICS
SALINITY INTRUSION: PLUNGING AND DENSITY CURRENT
SALINITY INTRUSION: PLUNGING AND DENSITY CURRENT
Qii
ah
PLUNGING POINT
U
SALINITY INTRUSION: PLUNGING AND DENSITY CURRENT
Qii
ah
PLUNGING POINT
U
ELLISON & TURNER (1959)
SALINITY INTRUSION: PLUNGING AND DENSITY CURRENT
Qii
ah
PLUNGING POINT
U
ELLISON & TURNER (1959)
SALINITY INTRUSION: PLUNGING AND DENSITY CURRENT
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
SALINITY INTRUSION: PLUNGING AND DENSITY CURRENT
EXCHANGE FLOWS
Q (m3/s)
DAILY MEAN FLOW RATES
DATE
SALINITY (PSS)
FRESH INFLOW
SALTY INFLOW
OUTFLOW
MIXING IN STRATIFIED FLUID
MIXING IN STRATIFIED FLUID
WIND MIXING IN TWO-LAYER FLUID
h1
h2
1
2
u*
WIND RICHARDSON NUMBER
MIXING IN STRATIFIED FLUID
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
MIXING IN STRATIFIED FLUID
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*
MIXING IN STRATIFIED FLUID
LET’S DO SOME THEORY IPPEN’S STYLE (e.g., HARLEMAN & IPPEN, 1966)
MIXING IN STRATIFIED FLUID
FRICTION FACTOR
GAIN IN PE
WIND INPUT
BULK MIXING EFFICIENCY
(TSENG & FERZIGER, 1998)
(0.2%)
MIXING IN STRATIFIED FLUID
LET’S TRY A DIFFERENT APPROACH!
MIXING IN STRATIFIED FLUID
MIXING EFFICIENCY
TKE BALANCE
TURBULENT DIFFUSIVITY
0.15 (WÜEST & LORKE, 2003)
h1
h2
S1
S2
u*
MIXING IN STRATIFIED FLUID
VALUE?
MIXING IN STRATIFIED FLUID
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
MIXING IN STRATIFIED FLUID
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
ENTRAINMENT VELOCITY
0
0.2
0.4
0.6
0.8
1
0 5 10 15 20
OCTOBER 18
DECEMBER 12
JANUARY 29z/H
S (pss)
MIXING IN LAKE BUDI
ENTRAINMENT VELOCITY
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
2826242220181614
0
8
4
DISTANCE (km)
DE
PT
H (
m)
SIMULATION OF LAKE BUDI HYDRODYNAMICS
SALINITY (pss)
MODELING SALINITY INTRUSION AND MIXING
OPEN
SIMULATION OF LAKE BUDI HYDRODYNAMICS
DISSOLVED OXYGEN CONCENTRATION (mg/l)
MODELING DISSOLVED OXYGEN CONCENTRATION
OPEN
SIMULATION OF LAKE BUDI HYDRODYNAMICS
PREDICTION IN THE CASE OF NATURAL MOUTH BAR OPENING
DISSOLVED OXYGEN CONCENTRATIONDENSITY (kg/m3)
OPEN OPEN
SIMULATION OF LAKE BUDI HYDRODYNAMICS
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 < 7
7< I < 100
I > 100
MOLECULAR
TRANSITIONAL
ENERGETIC
REGIMEI RANGE
CHECK!