Browsing by Author "Xu, Ruichen"

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Dual-Source Optimization of the “Diverting Water from the Yangtze River to Tai Lake (DWYRTL)” Project Based on the Euler Method
(Hindawi Publishing Corporation, 2020-08-04) Xu, Ruichen
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.
Influence of water diversion on spatial and temporal distribution of flow field and total phosphorus (TP) concentration field in Taihu Lake
(IWA Publishing, 2020-03-04) Xu, Ruichen
In order to evaluate the overall impact of water diversion on Taihu Lake, this paper carries out numerical simulation of the temporal and spatial distribution of the flow field and the TP concentration field in Taihu Lake based on measured data during the water diversion period by using the Euler–Lagrange method. The results show that: (1) the Pearson coefficient of monitoring points in the East Lake area increases significantly during the water diversion period, indicating that the diversion of water may indirectly influence water quality; (2) the diversion of water has a significant influence on the flow rate of the simulated stations in Taihu Lake, and the influence is Taipu (103%) > Gongwan (60%) >East Lake (31%); (3) when the amount of water flow transfer from the Wangyu River to the lake is greater than 100 m3/s, the mean concentration of TP in the Center and East lakes increases significantly (more than 50%). The recommended water diversion discharge is to be controlled in the range 100–200 m3/s and the total water diversion yield between 1.56 and 2.59 billion m3/a.
Study on pollution traceability based on the optimized hydrodynamic model of Tai Lake
(IWA Publishing, 2020-08-17) Xu, Ruichen
This research optimized a hydrodynamic model based on in-situ measurement experiments, which can evaluate the transport process of pollution groups from inflowing lake sources with different wind conditions and their effects on the sensitive area in Tai Lake. The results showed that the wind drag coefficient (Cs) was 0.001–0.0028 when the wind speed was 1–12 m/s, and the particle trajectory is validated well by the methods of Thiessen polygon and Lagrange particle tracking, which proves that this hydrodynamic model was optimized successfully. During the water diversion period, the results showed that the Northwest Area and Gong Bay are the most important pollution flux sources to the sensitive area. Under northwest wind condition, the pollution flux proportion from Northwest Area and Gong Bay is 65 and 17%, respectively. Under southeast wind condition, the pollution flux proportion from Northwest Area and Gong Bay is 48 and 27%, respectively. Namely, pollution control to the upstream watershed of the Northwest Area and improving the water quality (TP < 0.065 mg/L; TN < 1.2 mg/L) from the Wangyu river are the effective methods to reduce the pollution risks for the sensitive area.