Modelamento matemático para simulação do fluxo subterrâneo no aquífero aluvial no semiárido de Santa Luzia-PB.

Abstract

The alluvial shallow aquifers in the Northeast of Brazil have great social-economic importance for the small farmers of the region, i f they are adequately exploited. However, they are scarcely hydrologically investigated. The subject of this dissertation is part of a bilateral project that exists between the Hydrology Department of The Technical University in Hannover, Germany and the Civil Hydraulic Laboratory of the CCT/UFPB in Campina Grande- PB. This dissertation is an attempt to study, with numerical computational methods, hydrogeological properties of an alluvial aquifer with a 5 km length, a 50 to 400 m width and an irregular thickness of lm to 10m chosen near to Santa Luzia city - PB. The field measurements collected in 1988 (OLIVEIRA., 1992) by the B-41 project of the Northeast scientific and technological development program (PDCT-NE) were used as the input data in this modelling. In these studies carried out during 1987-1989 (SCHUSTER et aL, 1990) for the first time a numerical computational modelling was initiated with a one-dimensional hydrogeological model, that was too simple to meet the hydrogeological situation of the alluvium in study. In this dissertation a bidimensional model was used. A special approach was given for the calibration of hydrodynamical parameters of the alluvium studied before simulating the evolution of the freatic level with the time, implementing the recharge and evaporation effect from the precipitaion rates measured and empirical values of the regional evaporation. At the end of this study it was tried to establish a reasonable model to simulate the effects of pumping in the irrigation area, still rudimentary in this region, and of the two submersed dams installed in the flow of the alluvium in the 1954 year by the region's dwellers after the draught years in 1951-52. The modelling results show that there are still great deficiencies due to the lack of more experimental data and can only be used as an initial model for future simulations with new data.