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Challenges on modelling hydrodynamics in Bahía Blanca Estuary (Argentina). Francisco J Campuzano campuzanofj.maretec@ist.utl.pt www.ecomanage.info www.mohid.com www.ist.utl.pt. Bahía Blanca Modelling. Data made available :
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Challenges on modelling hydrodynamics in Bahía Blanca Estuary (Argentina) Francisco J Campuzano campuzanofj.maretec@ist.utl.pt www.ecomanage.info www.mohid.com www.ist.utl.pt INCO-CT-2004-003715
Bahía Blanca Modelling • Data made available : • Bathymetry with a 50 m resolution covering the inner part of the estuary • Tides for three years at three stations. INCO-CT-2004-003715
Bathymetric data provided INCO-CT-2004-003715
Bahía Blanca Modelling • Model History: • First attemp was to set only a model on the study area • Bad results due that FES 95.2 predictions for the area did not match the observed values • Boundary was taken further south to be able to simulate the amplification on the tidal wave INCO-CT-2004-003715
Bahía Blanca Modelling • Current State: • 2D model with three nesting levels • Tides within the area are similar to the one predicted with the tidal components • Rivers implemented (Sauche Chico River and Napostá Creek) INCO-CT-2004-003715
Tidal Validation retainer INCO-CT-2004-003715
Tidal Data INCO-CT-2004-003715
Simple Statistics INCO-CT-2004-003715
Analysis of the data • Tidal amplitude increase towards the head of the estuary, with ranges higher within the estuary than the outer station • Terms that explains the most of the tidal amplitude are mainly semidiurnal components (M2, L2, S2, L2, MU2), while can be appreciated also a influence from diurnal components (O1, K1) in addition as the tide moves to the inner part of the estuary the so-called compound tides generated by nonlinear interaction of primary constituent become increasingly important (M4, MS4, MN4). • Increase of the mean water level (Z0) of 70 cm in the relative short distance between the most distanced stations (≈ 55Km) INCO-CT-2004-003715
Mean Sea Level • Moving average on the hourly data is performed with a period of 25, which correspond to twice the time of a semidiurnal tide, strong variations on the level water can be appreciated at all stations at the same time and with the similar magnitude INCO-CT-2004-003715
Sea Level Pressure in Bahía Blanca region for the period 2001-2004 (NCEP reanalysis data). INCO-CT-2004-003715
Puerto Rosales monthly sea level records for the period 1967-1971 (Permanent Service for Mean Sea Level) INCO-CT-2004-003715
25 hours moving average water level in IW (blue line) and sea level pressure with a moving average of 4 (24h) for the period January-May 2001 INCO-CT-2004-003715
Tidal data filtered INCO-CT-2004-003715
Comments and Questions • Rejecting all frequencies with signals under 8766 h (365.24 days, SA, tidal component period), an annual pattern also appears on the tidal registry. • When filtering with 365 days (8760 h), a better curve can be observed that is not explained by the presence of the SA component as its amplitude is 9.897 cm, when the signal observed on figure presents an amplitude of around 20 cm. • Any suggestion to obtain better results and analysis on this? INCO-CT-2004-003715
Model Forcing INCO-CT-2004-003715
Comments and Questions • Time ref used 0.0, son model used was the one with 0.005´resolution, questions: • What is the time reference in such a big domain? • What about reference level? INCO-CT-2004-003715
Comments • The three stations that were used to validate the results were not showing the increase in the mean sea level previously commented • The model should be able to increase the mean level “naturally” as it was occurring in the “reality”. • For testing this hypothesis, real values were imposed at the boundary of the “son” model to see how the tidal wave behaves on our bathymetry. INCO-CT-2004-003715
Torre Mareográfica INCO-CT-2004-003715
Puerto Belgrano INCO-CT-2004-003715
Ingeniero White INCO-CT-2004-003715
Challenges • When using the nested models, how to set the reference and time level • Respecting mean sea level there are annual oscillations that in my opinion are going to be complicated to simulate or include in the model, and then those short period oscillations that can modify extremely the tidal prism. An option could be to use the “inverted barometer” that Angela is developing, though no forecast could be done unless doing it operational. Or decide to move on, only with the astronomical tides. • Are all these tidal gauges using the same level of reference? If yes, can we do something to increase the mean sea level (tried different manning with not much improvement, and it affects the shape of the tidal wave), if not, how can we decide which is the correct one (if any)? • Include wind to see the effect on our model of the so-called “sudestadas” that tend to pile up waters in the estuary. Could this be partly responsible for the increase on the mean sea level? INCO-CT-2004-003715