The Efficacy of Water Transfer on Nutrients Removal in the Tianjing Lake, Tiacang City, China

Abstract

Water pollution is a key environmental problem affecting modern day China. Increased human population, agricultural and advanced industrial activities present a complex multiple problems impacting water resource across China. This situation is more pronounced in Tianjing Lake, Tiacang City. Engineered in April 2012, the lake exemplifies severe eutrophication problems. Constructed for recreational uses, the lake plays a vital role in the economic and sociopolitical development of Tiacang City. As a result, the Tianjing Lake water transfer project was carried out in order to improve water quality and alleviate eutrophication. The project considered major field observations that monitored the lake’s nutrients concentrations (TN, TP, NH4, COD Mn) before and after water diversions. Results showed that the effects of water transfer on the overall water quality improvement in the lake seemed heterogeneous. The observed heterogeneity is as a result of the lake’s hydrodynamic conditions influenced by inflow tributaries. However, poor water movement resulting from the lack of outlet to actively expel pollutants may be a key factor compounding the lake’s internal nutrients management. This, however, dictates the engineering of additional flow directions in order to ensure better exchanges and additional nutrients removal through the expulsion via the outlet to improve water quality and sustain ecosystem health. Hence, this study provides useful information necessary to better understand the complex hydrodynamic and mass transport processes in the Tianjing Lake and present a road-map for future management decision-making.