Coupled improvements on hydrodynamics and water quality by flowing water in towns with lakes.

With the worsening environmental problems in the plain river network, flowing water has become important because of its obvious improvement effect. In order to solve water quality and water mobility problems of the river network in Shengze Town, this paper establishes four flowing water scenarios and compares the associated improvements in water quality and hydrodynamics of the river network with the use of coupled hydrodynamic and water quality models. It is identified as the best scenario to dispatch 20 m3/s of water from the Xiegang River downstream of the Qingxi River and 20 m3/s of water from Lake Xiangjiadang to Lake Beiyandang. Results of this scenario show a significant improvement in the water mobility of the river network in the southern area of the Qingxi River, with the flow rate increasing by 38.23%. The water quality in Lake Beiyandang has upgraded from Class V to Class IV (based on the Chinese water quality standards), and the water quality downstream of the Qingxi River has improved a lot. Findings in this work could provide references for the development of flowing water scenarios in similar watersheds.