Short- and long-term control of external and internal phosphorus loads in lakes—A scenario analysis

In this paper the structure and validation of the deterministic eutrophication model SALMOSED is discussed. It is applied to two lakes of different depths with a long history of cultural eutrophication. The simulation results are used to assess the short- and long-term efficiency of alternative measures for eutrophication control considering external and internal phosphorus loads. In the case of the shallow Lake Mueggelsee the control of the phosphorus release from the sediment by sediment dredging seems to be the only efficient method. To consolidate a mesotrophic steady state of Lake Mueggelsee in a long-term perspective, 10-year simulation runs show that single sediment dredging should be followed by a reduction of the external phosphorus load by at least 50%. The eutrophication of the medium-deep Lake Yunoko can be controlled by a significant reduction of the effluent phosphorus concentration. Additionally it is recommended to control the considerable internal phosphorus load of Lake Yunoko by artificial aeration/destratification or the more costly sediment dredging.