The precipitation may produce decreasing or rising water level. As it was demonstrated the relationship between the ENSO and the precipitation on the Southeastern South America (SSA) by several authors, presently work was aimed to establish relationships between the water table and the ENSO. This correlation also provides useful information about the predictability of the future piezometric levels for sustainability of groundwater resources.
Three pluviometric and freatimetric gauge stations were analyzed, with records measured between 1950 and 1997, period in wich the freatimetric information is valid and the El Niño observations are reliable. The same were considered because of the longitude and quality of the series (Rafaela, 9 de Julio and Pehuajó).
At Rafaela, for the series 1970-1997, the correlation between the monthly mean piezometric level and the ENSO could be considered as good, since the coefficient of correlation for El Niño 3 and the lag 11 months is 0.35, and for El Niño 4 and the lag of 12 months is 0.49. In this station, the relationship between El Niño events and the standarized piezometric anomalies is very good. To each El Niño event corresponds an important behavior change, reflected in the increase of the freatic level. The precipitation on the same station shows its better correlation with a lag 4 for El Niño 4, and with a lag 5 for El Niño 3+4.
At 9 de Julio, it exists good correlation between the precipitation and the piezometric amplitude for a series of 28 years (1956/1983), so much to annual level as monthly ones, but the correlation among the SST with the piezometric amplitude, the piezometry and the precipitation is low (0.12 for the first and the last, and extremely low for the piezometry). The best correlation for the precipitation corresponds for El Niño 4, that in all the stations show a lag of 4 months, although the signal is not strong.
At Pehuajó, the piezometry and the precipitation show good correlation so much at monthly as annual level, but its relationships with the signal of El Niño are not satisfactory, probably due to the shortness of the series records (1970 / 1987).
The main conclusion of this work is that the water table level is predictable in function of a predictor like El Niño and is believed that probably the coefficients of correlation between the freatic levels and the predictors could be improved by means of the application of an multiregressive analysis.
The analysis gives special attention to water table fluctuations registered with an approximate monthly periodicity, from wich trends and order of magnitude on direct recharge can be stablished.