ISOTOPIC ALTITUDE EFFECT AS A TOOL TO EXPLAIN THE BEHAVIOR OF SPRINGS IN CENTRAL EASTERN OF VERACRUZ, MEXICO

The study area is located in the central part of Mexico, in the state of Veracruz. Twenty rain collectors were placed for the seasons; 2007, 2008 and 2009, from an altitude of 10 to 4200 masl, covering a section of 90 km from the coast of Veracruz up to the top of the volcano Cofre de Perote. On this section 34 springs with altitudes from 160 to 4100 masl were sampled. These springs are the main source of water supply for more than 60 communities in the area. Also they are considered as representatives of local recharge, with conductivities between 50 to 125 μS/cm and temperatures close to the average local. From the isotopic results in rain and physicochemical characteristics measured in the springs, as well as climatic and topographic characteristics of the region, the isotopic value for the altitude effect was determined with a value of 0.5/200m for oxygen-18. It is assumed that this effect is caused due to the particular climatic regime of the area, creating a kinetic fractionation in the cloud masses that enter the continent.