Recarga de aquífero em aluvião no semiárido: estudo de caso em Pesqueira – PE

Abstract

Groundwater is gradually recognized as a viable alternative for users and has shown increasing use in recent years. The core of exploiting this type of resource is renewing the withdrawn water, or recharging the aquifer, which does not occur at the same rate as extraction. This can result in the exploitation of parts of the aquifer's permanent reserves, with risks of depletion, when abstraction is not properly monitored. This study aims to determine the recharge of the alluvial aquifer in the rural area of the Municipality of Pesqueira (PE). The area is located in the Ipanema River Basin, in the transition between the Agreste and the Semiarid of the state. The methodology used was water balance and water level variation to quantify recharge, a typical system used in the semi-arid region of Northeast Brazil that uses groundwater for family farming. The region's rainfall, average monthly temperature, water level in Amazon-type wells and piezometers across the entire length of the alluvial valley, from the Flexeira Velha area, further upstream to the Nossa Senhora do Rosário area, were analyzed. The region's climate is defined as “initial dry” (January and February), rainy (March to August) and “final dry” (September to December). The accumulated recharge in the period under analysis was 1501.5 mm using the Thornthwaite and Mather water balance method, which was sufficient to overcome the soil's water deficit. The water level variation method quantified an accumulated recharge of 1652.4mm distributed over the years of the period considered. The difference in the results of the methods presented is justified by the first considering climatological and soil elements for the analysis of the aquifer and the second method directly analyzes the variation in the level, being more appropriate in estimating recharge.