El uso del suelo en las cuencas de captación condiciona la calidad del agua en embalses del sudeste peninsular ibérico

We studied the total nitrogen (TN) concentration, the total phosphorus (TP) concentration, and the TN/TP ratios in 12 reservoirs located in the southern Iberian Peninsula, to study the influence of land-use in the reservoir watershed on the trophic status of these systems. The TN/TP ratios indicated limitation by P or co-limitation depending on the system. Only the percentage of agriculture areas significantly classified the reservoirs by their P and N concentrations, while the percentage of urban areas also grouped the reservoirs by their N contents, according to the univariate tree regression analyses. We found a positive relationship between the percentage of agriculture areas and the trophic state of the reservoirs, according to the Carlson index (TSI), that indicates a deterioration in water quality in the reservoirs induced by agricultural activity.