Water diversion and allocation for typical confined polder river-net in Taihu Basin

Abstract

Hydraulic restoration in a confined polder river-net is a new issue under the concept of the Interconnected River System Network (IRSN) proposed by the Ministry of Water Resources (MWR) in China. This paper studies the typical hydrographic connection in the polder, and analyses the current situation of the hydrographic river-net in the typical area of Subaiwei in Changshu City by setting up a one-dimensional unsteady hydrodynamic model. The best water diversion-allocation schemes in the confined polder river-net are simulated and optimized in various scheduling rules. In order to recover the ability of hydro-connection and stream function, the effects of different scheduling rules and the duration time of water diversion under the ability of pump stations around polder boundary are compared. The results show that the optimized injects can enhance the total flow velocity and the exchange rate is more than 20% on average in various streams. This study is critical for the sustainable utilization of limited clean water in a confined river-net polder, and for quantifying the water ecological recharge for hydrodynamic connection.