Enrique D'Onofrio

Changes in the Regime of Storm Surges at Buenos Aires, Argentina

Abstract Located on the west margin of the Rio de la Plata estuary, the capital city of Buenos Aires is often affected by positive and negative storm surges due to strong southeasterly and northwesterly winds, respectively, which sweep the estuary. While positive surges cause severe flooding, negative surges affect navigation and drinking water supply. Since Buenos Aires is densely populated, a quantitative assessment of the variations in the regime of storm surges will help to develop policies for reducing their impacts. Changes in frequency, duration, and height of storm surges over the period 1905–2003 were determined from statistical analyses of hourly water levels. Calculations of the tidal constants used harmonic analyses of 19 y periods to account for any variation in the astronomical tide. Positive and negative surges were chosen from the residuals between observed levels and the predicted tide. The results show that the decadal averages of frequency and duration for positive surges have increased in the last three decades, but they have decreased for negative surges. The average decadal trends of the maximum positive and negative surges in each year, +1.46 ± 0.08 mm/y and +1.02 ± 0.09 mm/y, respectively, compare well with the relative mean water-level rise for Buenos Aires: +1.68 ± 0.05 mm/y. However, the height of positive surges has decreased in the last decade, and negative surges have become more intense in the last two decades.

Simplified empirical astronomical tide model-An application for the Río de la Plata estuary

The Rio de la Plata has a complex astronomical tide due to the effect of the shallow depth of this extensive estuary, the complicated geometry and bathymetry and the huge discharge of the rivers Parana and Uruguay and therefore the simulation of the astronomical tide is complicated. This paper presents a Simplified Empirical Astronomical Tide model (SEAT) which overcomes the foreseen difficulties in a straightforward way. The program developed can be applied to other regions by only changing a file of the dynamic-link library. SEAT provides predictions, harmonic constants and the mean water level referred to the tidal datum used to calculate the prediction. The storage of information in the form of images reduces the size of the application. The equations considered for the prediction do not require the use of special computer processors. A personal computer with minimum hardware that supports Microsoft Framework 3.5 is suitable to run SEAT.