Tidal Effect on Chemical Spills in San Diego Bay

Transcription

1 Tidal Effect on Chemical Spills in San Diego Bay Pete C. Chu, Kleanthis Kyiakidis Naval Postgaduate School, Monteey, CA, USA Steven D. Haege Naval Oceanogaphic Office, Stennis Space Cente, MS, USA Mathew Wad Applied Science Associates, Inc.,.Naagansett, RI, USA Fist Intenational Confeence on Physical Coastal Pocesses, Management, and Engineeing, WIT, Malta, Septembe 14-16, 2009

2 San Diego Bay Impotance fo Homeland Secuity Lage City Host of a significant pat of US Navy Nea the Mexican bode Weak winds Tidally diven basin

3 Homeland Secuity: Chemical Attack o Accident

4 (1) Basic envionmental conditions in San Diego Bay

5 Bottom Topogaphy

6 Chaacteistics T ~ 21 o C (ange 14 o 26 o C). S ~ 35 ppt (ange ppt)

7 Wind contibution to total focing U component fo nb1 (cm/sec) /5/1993 0:00 7/10/1993 0:00 7/15/1993 0:00 Time (day) Cuents Cuents poduced by tides ( tidal pumping caused by the flow diffeence between ebb and flood). Winds insignificant effect. Both westely aftenoon winds and eastely moning/ evening winds less than 5 m/sec Annual Annual pecipitation 0.26 m (in summe negligible less than m). No significant ive inflow

8 Semi-diunal and Diunal Tides K L P Q T Q RHO SA SSA J M LAM OO N MU NU O K N S M2 1 Epoch (degees) Amplitude (m) Name

9 ADCP Stations (SPAWAR) Measuing Cuent Velocity

10 Cuents at NB2 station fo suface (yellow), middle depth (puple) and bottom (blue) U in wate column fo NB2 V in wate column fo NB U ( cm /s) 0 V (cm/s) time (in 10 s) time (in 10 s)

11 (2) Hydodynamic modeling

12 Wate Quality Management and Analysis Package (WQMAP) WQMAP is an integated modeling system designed to pedict hydodynamic featues (cuent velocity, suface elevation, ) and suface wate quality.

13 Featues of WQMAP Integated Geogaphic Infomation System Gid Geneation Hydodynamic Model Pollutant Tanspot Model All models use same computational gid Applicable within egions such as ives, lakes, estuaies, bays and coastal seas.

14 Hydodynamic model Hydostatic Tidal focing (tidal hamonic at the open bounday fom NOAA) Land boundaies assumed impemeable (nomal component of velocity set to zeo). At closed boundaies tanspot of substance (i.e. salinity) is zeo. At open boundaies, concentation specified duing the inflow, using chaacteistic values.

15 Basic Equations d + Δ v = 0 dt dv + (2 Ω v) = p gk + dt dt dp c βt = q σ p dt dt = ( T, S, p) ds dt = κ ( S ) S T τ xx τ T τ yx τ τ zx τ q heat flux c p κ specific heat β themal expansion S xy yy zy τ τ τ xz yz zz molecula diffusion

16 Hydodynamic Model. cos and ), ( whee, ) ( 0 ) ( ) cos ( cos ˆ ) ( cos 2 ˆ ) ( 1 sin 2 tan ˆ ) ( cos 1 ) sin (cos 2 tan w v u t dt d T p c c T dt dp c T dt dt w v u dt d g p u v u dt dw u vw u dt dv v w uw uv dt du p p p = = = = = Ω = Ω = Ω + + φ λ φ σ κ β φ φ λ φ φ φ φ φ φ λ λ φ φ φ φ T T T

17 Model Evaluation Red Obsevation, Blue - Modeling V fo nb U fo nb1 V (cm/sec) /10/1993 0:00 7/15/1993 0:00 7/20/1993 0:00 7/25/1993 0:00 Time (date) U (cm/sec) /10/1993 0:00 7/15/1993 0:00 7/20/1993 0:00 7/25/1993 0:00 Time (date)

18 MODEL EVALUATION/ VELOCITY COMPONENTS Coelation Coefficient : 0.92 Relative Root Mean Squae Eo: 0.09

19 MODEL EVALUATION/ ELEVATION NOAA SPAWAR M2 (ampl dif) cm cm K1 (ampl dif) cm cm O1 (ampl dif) cm cm S2 (ampl dif) cm cm M2 (ph dif) o o

20 (3) Chemical Dispesion

21 Chemical Dischage Model System (CHEMMAP) CHEMMAP is a chemical dischage model designed to pedict the tajectoy, fate, impacts and biological effects of a wide vaiety of chemical substances theedimensionally.

22 CHEMICAL Dispesion SCENARIOS Released in Noth and South San Diego Bay) Methanol (1 bael eleased in depth 1 m). Chloobenzene (200 tons in depth 1 m).

23 Pollutants Released at Noth San Diego Bay

24 2 days 32 days

25 Fast Tempoal Reduction of Chemical Concentation

26 Pollutants Released at South San Diego Bay Afte 12 hous

27 15 days 32 days

28 Slow Tempoal Reduction of Chemical Concentation

29 Conclusions Two Types of Chemical Dispesion in San Diego Bay Geat dange/ vulneability: In the Noth San Diego Bay, contamination of city/pot, Bay small eaction time. In the South San Diego Bay, contamination only of Southen pat (including Naval Station).

30 Conclusions Hydodynamic-chemical chemical modeling is vey impotant fo habo safety and waste wate management.