Ecological strategy for eutrophication control

Water monitoring results of the Danjiangkou Reservoir indicated that total nitrogen and total phosphorus concentrations are high and therefore worse than required for central drinking water supplies. Nutrients including nitrogen and phosphorus accumulated in the bank cultivated land were greater than those contained within the river estuary sediment as well as in the reservoir bay sediment. This implies that high concentrations of loosely exchangeable phosphorus (166.53 mg/kg) in cultivated land could, after the completion of the dam heightening project, easily lead to the development of algal blooms. Serious water and soil loss occurring in the reservoir area will promote the transportation of non-point source pollution mainly caused by untreated agricultural domestic wastewater, chemical fertilizer and livestock farming, which accounted for more than 50%of the total basin's nutrient input loads. Ecological control techniques were therefore the first choice for nutrient reduction and water quality guarantee in the Danjiangkou Reservoir. In order to guide the ecological restoration process, leading international ecological methodologies were summarized and compared, taking into consideration aspects of engineering, as well as ecological, biological, environmental and economic advantages and disadvantages. Finally, novel ecological filtration and a purification dam were designed for eutrophication control.