Spatial and temporal dynamics of nutrients during the first filling years of a Mediterranean reservoir

The spatio-temporal evolution of classical limnological variables has been studied in a Mediterranean reservoir: Rules, in the province of Granada, after its inauguration. The dynamics of nutrients and chlorophyll-a is strongly conditioned by: (i) contributions through fluvial waters; (ii) the photosynthetic activity in the upper layers of the water column and (iii) the accumulation of orthophosphate and ammonium in the anoxic hypolimnion during summer thermal stratification. The sedimentation rate in Rules Reservoir shows a clear increasing gradient in the dam-tail direction, reflecting the important contribution of allochthonous fluvial material. Finally, the comparison of the total concentrations of phosphorus and nitrogen after 10 years of operation, in which, among other factors, the purification of wastewater in the catchment basin has improved, has shown a drastic decrease.