MEDIDAS DE 18O E HIDROQUÍMICA DE ÁGUAS SUPERFICIAIS E SUBTERRÂNEAS NO ESTUDO DA INTERAÇÃO RIO – AQÜÍFERO, NA REGIÃO DE LIMOEIRO DO NORTE – BAIXO JAGUARIBE – CE

For an investigation in losses of river flow of Jaguaribe river, in the region of Limoeiro do Norte, surface and groundwater samples were taken, in dry and rainy seasons, during a period of 2 years. Oxygen-18 and hydrochemical analyses were performed to avaluate the origin of aquifer recharge and river/aquifer interaction. Results show pronounced differences in 18O between Jaguaribe river (mean: +1.6) and the Jandaira aquifer (mean:-2.4), strong seasonal variations in 18O in the river water, positive values for this parameter in some wells, indicating the influence of the river, and chemical homogeneity of Jaguaribe river water and those from the majority of wells. A general analysis of the data indicates a constant recharge to the alluvial aquifer though river water, however more pronounced during dry seasons.