Author(s): Liping Xu; Xueping Gao; Chen Zhang
Keywords: Urban artificial lake; Water diversion，Water renewal; Renewal time; Three-dimensional modeling; Hydrodynamic
Abstract: Appropriate water diversion is one of the most effective methods of improving water quality in lakes, especially urban artificial lakes, where water renewal is crucial for sediment transport and ecological environment protection. Water renewal depends on hydrodynamic processes and can have a complex spatial distribution due to irregular topographic features. Water renewal time scales are not directly observable but are derived indirectly from computational studies. Lake Dragon, situated in eastern Zhengzhou city Henan Province of China, is an urban artificial lake with complex irregular boundaries. For the purpose of assessing water renewal capability, a three-dimensional hydrodynamic model, was developed to simulate the impacts of water diversion projects on the transport of dissolved tracer by using the concept of water renewal time. The model was calibrated and verified with the inflow and outflow based on the principle of water balance. Model results show that the effect of water diversion on transport processes in the lake is strongly influenced by hydrodynamic conditions induced by inflow/outflow tributaries. A series of numerical simulations using idealized simplifications provides detailed insight into water renewal pathways and regional differences in renewal timescales. Water in the central lake is fully renewed over 30 days because of insufficient water channels connected to the outside water domain. However, a short water renewal time exhibits in the outer part and river channels within about 14 days. The simulated results can provide useful information for understanding the transport processes and guidance for operation management and landscape maintenance in urban artificial lakes under water diversion projects.