Application of factor analysis to the study of contamination in the aquifer system of Ayamonte-Huelva (Spain)

The growth of cultivation (strawberries and citrus fruits) in the coastal region of the Huelva province of Spain in the last 10 years has meant an increase in the demand of water from the Ayamonte-Huelva aquifer system, It has also meant the introduction of an excess of nitrogen via fertilizers from farming. The system now has two problems: salt-water intrusion in the southern sector (Gonzalez and Romero, 1991; Gonzalez, 1992); and a general increase in the nitrate content in the saturated zone, This second problem has led to average concentrations of nitrates in the aquifer above potable limits (50 ppm), reaching local values near to 400 ppm of NO3- (Gonzalez and Romero, 1991; Grande et al., 1993). This paper delineates the sphere of influence of the two factors being considered (salt-water intrusion and agricultural contamination) on the different variables studied, The proximity between both factors is justified for each of the contaminating processes.