The effects of flushing with NO3 and Ca rich water on shallow eutrophic lakes

A long term computational results and sensitivity analysis of the eutrophication model, incorporating phytoplankton, submerged macrophytes and nutrient dynamics in sediments were performed for understanding the effects of macrophytes on algal blooming in shallow lakes. The model was successfully reproducing long term change experienced in Lake Veluwe (The Netherlands). The model also described the reduction of phosphate return flux from the sediment and phytoplankton biomass and the resulting development of macrophytes under improved light condition after restoration measurement of the lake by artificial flushing of nitrate rich water into the lake and reduction of external phosphorus loading. Numerical experiments reproduced the following phenomena successfully: the blooming after the initiation of macrophyte growth has a remarkable effect on the following macrophyte development, thus with higher nutrient load, the macrophytes are significantly depressed. Sensitivity analysis of important coefficients show that the maximum photosynthesis rate, the conversion rate from oxygen to ash free dry weight are most sensitive parameters for macrophyte and algal development.