Dual-Source Optimization of the “Diverting Water from the Yangtze River to Tai Lake (DWYRTL)” Project Based on the Euler Method

Abstract

Appropriate water body diversion can improve the water quality of Tai Lake. Excessive diversion of water would, however, dramatically alter the local flow fields, which are not conducive to the growth of aquatic plants and the stability of ecosystems. The current “Diverting Water from the Yangtze River to Tai Lake (DWYRTL)” project uses a single water source, the Wangyu River, for diversion, a model that may significantly affect the nearby flow rate or uniformity of the lake and is not conducive to the long-term stability of the aquatic ecosystem in the Tai Lake district of the eastern part of the lake. In order to simulate the different situations of single- and dual-source water diversions (Wangyu-Xinmeng Rivers) in Tai Lake, we based this study on a three-dimensional hydrodynamic model coupled with the Euler method, which can accurately calculate the water exchange rates in the different districts of Tai Lake. The results show that (1) it is recommended that the total annual diversion of water should not exceed 20 × 108 m3; (2) the wind field is the most important factor determining the distribution of spatial water exchange; (3) under wind-free conditions, the flow rate of a single-source diversion of water is approximately 50% higher than that of dual-source diversion; and (4) water diversion under the prevailing conditions of the northwest wind in winter will reduce the semiexchange period of the eastern part of the lake area from 50 to 30 days, significantly changing the nearby district’s uniformity, leading to ecological risks. Therefore, it is recommended that the dual-source water diversion mode be used in winter and windless season, and single-source water diversion mode be used in other seasons.

Study on the proportion and flow path of Yangtze River water diversion into Taihu Lake

“…In addition, due to the high water level of the Wangyu River during the diversion period, there was very little diversion from the Baiqu River, the Zhangjiagang River, and the Xicheng River entrance through the reciprocating river network into the Wangyu River. Therefore, the WYR pathway was less affected by the external water volume, which could be the highest quality water access filling water for Taihu Lake compared with the other pathways (Yan 2018;Xu et al 2020a).…”

“…A series of water diversion and drainage projects in The Taihu basin began to be implemented from this period. In 2002, the 'Yangtze-Taihu Water Diversion ' project of Wangyu River began to run formally (Li et al 2013b), the construction of the diversion station along the Yangtze River in Wucheng Area also has been constantly improved, and the water diversion has also begun to rise steadily (Xu et al 2020a). Over the past 30 years, the YRD has increased by 84%, while the WITL has increased by 95%, which shows that there is a close relationship between the two, but the proportion of the YRD and how to reach the Taihu Lake through the Grand Canal still need to be quantified by hydrodynamic model .…”

“…With the implementation of the water diversion project from the Yangtze River to Taihu Lake (WDYT) and the construction of increasingly intensive regional water conservancy projects, a large number of studies have shown that artificial external water diversion is highly correlated with changes in the residence period in Taihu Lake (Hu et al 2008;Zhai et al 2010). However, previous studies have focused on the influence of water diversion on the hydrodynamics and water quality of Taihu Lake, focusing on the internal migration and transformation process of the lake body after water diversion (Li et al 2013a(Li et al , 2013bXu et al 2020a). Very little research has been done on the flow process in the river network from the Yangtze River to the entrance of the lake, which leads to an unclear knowledge of the weight of the water diversion in the lake volume and the route into the lake in the complex river network.…”

Uncertainty and Sensitivity Analysis of Input Conditions in a Large Shallow Lake Based on the Latin Hypercube Sampling and Morris Methods

“…In order to further the comparison between the simulation results and the real value of the water level, this study adopted the average relative error (MRE), root mean square error (RMSE), analysis of correlation coefficient (R 2 ), and the coefficient of Nash model (NSE) to evaluate the measured data (M) and the simulated data (S). The specific formulas are as follows [31]: In order to further the comparison between the simulation results and the real value of the water level, this study adopted the average relative error (MRE), root mean square error (RMSE), analysis of correlation coefficient (R 2 ), and the coefficient of Nash model (NSE) to evaluate the measured data (M) and the simulated data (S). The specific formulas are as follows [31]:…”

“…The specific formulas are as follows [31]: In order to further the comparison between the simulation results and the real value of the water level, this study adopted the average relative error (MRE), root mean square error (RMSE), analysis of correlation coefficient (R 2 ), and the coefficient of Nash model (NSE) to evaluate the measured data (M) and the simulated data (S). The specific formulas are as follows [31]:…”