A two-year survey of the physicochemical parameters and nutrient speciation in a lower Oum Rabiaa basin, characterized by three dams in series (Imfout, Daourat and Sidi Maâchou), was performed from December 1998 to November 2000.
The presence of the three dams in series is responsible for the nitrogen and phosphorus loads in the dams because of the reduction of fluvial contributions to the lower sector. Multivariate statistics were used to identify the principal factors influencing water chemistry in the individual dam systems. The three dams are influenced mainly by nutrient and organic sources. The eutrophication status of the studied systems was evaluated by N/P ratios. Mean N/P ratios at the three dams showed a high likelihood of P-limitation. Highest values were observed primarily during winter and early spring.