Regulation and management of lake eutrophication in urban regions based on an improved model for aquatic ecosystem simulations

The construction of a model based on an analytic system and dynamic structure is an important technique in lake manage-ment. The Yan-Model conducts system simulations based on the dynamics of the main aquatic species but does not include filter-feeding fish and N elements, which have important effects on eutrophication. Based on the Yan-Model, modules for the filter-feeding fish A. nobilis and the N cycle were constructed and combined to form a new model, the Yan-Model II. After model calibration and validation, a scenario analysis was performed to simulate eutrophication regulation and external pollution impacts. The results show the following: (1) the simulated and measured values of the lake ecosystem were highly consistent (R > 0.9, RSR < 0.7); (2) an eutrophic lake could be effectively restored by planting Vallisneria natans (Lour.) Hara with low biomass density; (3) assuming that urban sewage drained into the lake, equal or more than 600 m3 of urban sewage would lead to an increase in the Chl-a concentration to a level that exceeded the eutrophication threshold; and (4) an Aristichthys nobilis density of 50 g/m3 had a strong ability to control phytoplankton growth. Using the improved model, this study successfully guided the ecological restoration of Dongshan Lake. This model can be used for lake management and sustainable development in urban ecosystems.