Hydrogeology of Brasília (DF) Sobradinho river basin

Abstract

Storm surges over the Atlantic Coast of South America have important effects in terms of coastal erosion, sediment dynamics and harbor activities, among many others. The aim of this project is to present a numerical system for storm surge forecasts in the South-Western Atlantic Ocean, basically from the northern Argentinean shelf (42 • S) to the Rio de Janeiro coast (21 • S), hereafter called SWAO region. The idealized system would be able to provide disturbances in the surface elevation and shelf currents fields related to the passage of meteorological systems over the studied area. It is very important to mention the cyclogenetic characteristics of the region of interest, which play an important role for storm surge events.Mesoscale meteorological forecasts for the study area can be supplied by operational runs of the Regional Atmospheric Modelling Systems (RAMS) at the Department of Atmospheric Sciences of University of São Paulo. The model assimilates large scale analysed and predicted fields provided by global models (normally NCEP and CPTEC, and occasionally ECMWF) and improves the forecast considering regional aspects in a 32km grid.The oceanic part of the proposed system is based on the Princeton Ocean Model (POM) simulations for the SWAO area with approximately 10km resolution, which will be forced by predicted wind fields provided by RAMS as described above. The use of mesoscale wind fields in previous hindcasting simulations shown better results in comparison to wind fields directly from global models.- ( November 19, 1999 ) . SUMMER CONVECTION IN URBAN ENVIRONMENTS AND THE FLASH FLOODS Augusto J. Pereira FilhoDepartamento de Ciências Atmosféricas, Instituto Astronômico e Geofísico, Universidade de São Paulo.Presented by Igor G. PaccaThe Metropolitan Area of São Paulo (MASP) is one of the largest urban environments of the planet with about sixteen million inhabitants. Flash floods in the MASP are more often in the summer (Pereira Filho et al. 1991). Anomalous atmospheric circulation patterns developed under the influence of the El Niño in South America during February 1998. A large-scale high-pressure system anomaly over the State of São Paulo inhibited organized rainfall. Rainfall accumulations were above average along the coastline and below average elsewhere (Climanálise 1998). Furthermore, heavy showers and flash floods were above average in the MASP within this period. These events were monitored with the São Paulo weather radar (Braga Junior 1988). Radar measurements were used to estimate the rainfall spatial frequency and distribution. The results indicate a nucleous of rainfall accumulation over the MASP higher than four times the spatial average An. Acad. Bras. Ci., (2000) 72 (2)