Appled numericl modeling to the analysis of sea intrusion in the south of Recife Coastal Plain (PE) / Modelagem numÃrica aplicada à anÃlise da intrusÃo marinha na regiÃo sul da PlanÃcie do Recife (PE)

AUTOR(ES)
DATA DE PUBLICAÇÃO

2005

RESUMO

Groundwater is considered a safe and well protected source of water supply, and in some places it should be used as a strategic reserve. However, lack of adequate management in coastal aquifers has led to several problems, including seawater intrusion. Recife metropolitan region encompasses 14 towns and 14 mÂ/s of water supply demand, facing problems with deficit. A drought during 1998 and 1999, caused by low precipitation rates, led to severe crises with the surface water reservoir reaching very low storage levels. As a consequence, the number of operating well increased. This work aims to analyse the possibility of seawater intrusion in Cabo aquifer, considering the scenario of over-exploitation. The Cabo Aquifer is confined, while the upper aquifer, the Boa Viagem, is a phreatic formation, which presents water contaminated by several different sources. The neighborhoods of Boa Viagem and Pina in Recife, and Piedade in JaboatÃo dos Guararapes, have been chosen as the study area. Analyzing the monitoring on electric conductivity, it was possible to define critical points in the area. The conceptual model SHARP version 1.1 of 10/05/99, developed by USGS, has been chosen for the computational modeling. Data from previous field investigation and studies were used. For the omputational modeling two grids were defined in three cross sections to the coast line, which enclose 15 km, being 5 km on sea and 10 km on continent for a grid, and 5 km being km on continent and 5 km on the sea for the other grid. The results confirm the drawdown in the potenciometrics levels caused by the over- exploitation of the aquifers, which may led to vertical flow from the upper aquifer under contaminated conditions and increases the risk of "upconings" operating wells. The application of injection wells forming hydraulical barriers presented efficiency against the generalized advance of the saline interface, but it does not guarantee protection against "upconings". On the other hand, the application of injection wells in diverse points, presented the best efficiency against "upconings" and against drawdown in potentiometric levels

ASSUNTO(S)

coastal aquifers modeling salinization modelagem aqÃÃfero costeiro salinizaÃÃo engenharia civil

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