Resumo

CARRICA, Jorge C.  e  LEXOW, Claudio. Natural recharge evaluation of the aquifer in the upper Arroyo Napostá Grande basin, province of Buenos Aires. Rev. Asoc. Geol. Argent. [online]. 2004, vol.59, n.2, pp.281-290. ISSN 0004-4822.

The upper river basin of Napostá Grande creek constitutes an area of interest for ground water exploitation as an alternative source of water supply to Bahía Blanca city and other urban nuclei of the region. The phreatic aquifer in this area receives direct rain recharge through the unsaturated zone, recharge located in the piedmont area and indirect recharge from bank storage during the streamflow peak in smaller quantity. The objective of the study is to determine quantitatively the recharge and the ranking of the mentioned mechanisms through different methods: daily hydrologic balance both on basin scale (Visual Balan program) and soil (Balshort program); chloride balance between rainwater and groundwater and analysis of the hydrograph recession curve. The main mechanism of groundwater recharge occurred in the piedmont area. According to the used method of estimation, the total groundwater recharge is about 7 and 9% of the annual precipitation average.

Palavras-chave : Groundwater; Recharge; Water balance; Chloride balance; Recession curve.

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