1. Yarko Niño Department 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

2. … 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

3. 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)

4. THE SYSTEM

5. RIVER AND LAKE BUDI 38º 52` 73º 22` BUDI RIVER MOUTH LAKE BUDI THE SYSTEM 15 km

6. THE SYSTEM 28 26 24 22 20 18 16 14 0 8 4 DISTANCE (km) DEPTH (m) DISSOLVED OXYGEN (mg/l) 28 26 24 22 20 18 16 14 0 8 4 DEPTH (m) DISTANCE (km) SALINITY (pss) SALINITY STRATIFICATION AND DISSOLVED OXYGEN

7. THE SYSTEM BUDI RIVER MOUTH (ICOL)

8. THE SYSTEM ARTIFICIAL OPENING

9. THE SYSTEM ARTIFICIAL OPENING

10. 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

11. RIVER AND LAKE SALINITY INTRUSION DYNAMICS

12. 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

13. SALINITY STRUCTURE PRIOR 2ND OPENING OCTOBER 2 DISTANCE (km) 0246810121416182022242628 8 6 4 2 0 Z (m) SALINITY (pss) 18 16 14 12 10 8 6 4 RIVER AND LAKE SALINITY INTRUSION DYNAMICS

14. SALINITY STRUCTURE 2WEEKS POST 2ND OPENING OCTOBER 18 DISTANCE (km) SALINITY (pss) 18 16 14 12 10 8 6 4 02468 121416182022242628 8 6 4 2 0 Z (m) RIVER AND LAKE SALINITY INTRUSION DYNAMICS

15. SALINITY STRUCTURE 10 WEEKS POST 2ND OPENING DECEMBER 18 DISTANCE (km) SALINITY (pss) 18 16 14 12 10 8 6 4 02468 121416182022242628 8 6 4 2 0 Z (m) RIVER AND LAKE SALINITY INTRUSION DYNAMICS

16. 0246810121416182022242628 8 6 4 2 0 COMPLETE MIXING! SALINITY STRUCTURE 17 WEEKS POST 2ND OPENING JANUARY 29 DISTANCE (km) Z (m) SALINITY (pss) 18 16 14 12 10 8 6 4 RIVER AND LAKE SALINITY INTRUSION DYNAMICS

17. SALINITY INTRUSION: PLUNGING AND DENSITY CURRENT

18. QiQi ii aa h PLUNGING POINT U

19. SALINITY INTRUSION: PLUNGING AND DENSITY CURRENT QiQi ii aa h PLUNGING POINT U ELLISON & TURNER (1959)

20. SALINITY INTRUSION: PLUNGING AND DENSITY CURRENT QiQi ii aa h PLUNGING POINT U ELLISON & TURNER (1959)

21. SALINITY INTRUSION: PLUNGING AND DENSITY CURRENT DENSITY CURRENT IN THE LAKE (2 WEEKS POST 2ND OPENING) DISTANCE (km) 5 10 152025 Z (m) FREE SURFACE DENSITY CURRENT FIELD OBSERVATIONS

22. SALINITY INTRUSION: PLUNGING AND DENSITY CURRENT EXCHANGE FLOWS Q (m 3 /s) DAILY MEAN FLOW RATES DATE SALINITY (PSS) FRESH INFLOW SALTY INFLOW OUTFLOW

23. MIXING IN STRATIFIED FLUID

24. WIND MIXING IN TWO-LAYER FLUID h1h1 h2h2 11 22 u*u* WIND RICHARDSON NUMBER

25. 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

26. MIXING IN STRATIFIED FLUID EXPERIMENTS (NIÑO ET AL., 2003) (KRANENBURG, 1985; MONISMITH, 1986) ue/u*ue/u* Ri *

27. MIXING IN STRATIFIED FLUID LET’S DO SOME THEORY IPPEN’S STYLE (e.g., HARLEMAN & IPPEN, 1966)

28. MIXING IN STRATIFIED FLUID FRICTION FACTOR GAIN IN PE WIND INPUT BULK MIXING EFFICIENCY (TSENG & FERZIGER, 1998) (0.2%)

29. MIXING IN STRATIFIED FLUID LET’S TRY A DIFFERENT APPROACH!

30. MIXING IN STRATIFIED FLUID MIXING EFFICIENCY TKE BALANCE TURBULENT DIFFUSIVITY  0.15 (WÜEST & LORKE, 2003)

31. h1h1 h2h2 S1S1 S2S2 u*u* MIXING IN STRATIFIED FLUID VALUE?

32. MIXING IN STRATIFIED FLUID z/H u/u s z/H K/u s 2 K-  MODEL WITH BUOYANCY EFFECTS VELOCITY TKE

33. MIXING IN STRATIFIED FLUID K-  MODEL WITH BUOYANCY EFFECTS z/H u/u s

34. MIXING IN LAKE BUDI

35. ENTRAINMENT VELOCITY z/H S (pss)

36. MIXING IN LAKE BUDI ENTRAINMENT VELOCITY WIND VELOCITY (m/s) u e /u *  2  10 -5 Ri *  2.2  10 4 

37. MIXING IN LAKE BUDI ue/u*ue/u* Ri * 

38. MIXING IN LAKE BUDI MIXING DUE TO BENTHIC BOUNDARY LAYER TURBULENCE 28 26 24 22 20 18 16 14 0 8 4 DISTANCE (km) DEPTH (m)

39. SIMULATION OF LAKE BUDI HYDRODYNAMICS

40. SALINITY (pss) MODELING SALINITY INTRUSION AND MIXING OPEN SIMULATION OF LAKE BUDI HYDRODYNAMICS

41. DISSOLVED OXYGEN CONCENTRATION (mg/l) MODELING DISSOLVED OXYGEN CONCENTRATION OPEN SIMULATION OF LAKE BUDI HYDRODYNAMICS

42. PREDICTION IN THE CASE OF NATURAL MOUTH BAR OPENING DISSOLVED OXYGEN CONCENTRATION DENSITY (kg/m 3 ) OPEN SIMULATION OF LAKE BUDI HYDRODYNAMICS

43. 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

44. THANKS TO: FELIPE SANDOVAL CLAUDIA RODRIGUEZ MANUEL CONTRERAS

46. MIXING IN LAKE BUDI TURBULENT INTENSITY PARAMETER (IVEY ET AL., 2008) I ≈ 0.15 Re * ≈ 3  10 4 Ri * ≈ 2  10 4 L i /h 1 ≈ 0.2  LAKE BUDI WUEST & LORKE (2005): I ≈ O(1) AT LAKES THERMOCLINE EXPERIMENTS NIÑO ET AL. (2003): I ≈ 1-15

47. 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!