Determination of the mechanism of recharge in the Los Naranjos Area in Mexico using environmental isotope techniques

Abstract

The Río Blanco crosses a coastal plain south of Veracruz in Mexico, and discharge measurements suggested that the river was recharging the groundwater system. The estimated evapotranspiration is very close to the mean annual precipitation, so estimates of effective recharge by infiltration of precipitation are very imprecise. The variations in the stable isotopic composition (D and 18O) of surface and groundwater samples are used to estimate the relative importance of the two sources of recharge to the groundwater system. The data indicate that recharge by infiltration of precipitation is the dominant source of recharge. This conclusion is based upon measurements from individual wells and also on the base flow of rivers originating in the plain, thus providing an estimate integrated over the area drained by the rivers.