关键词: 平原河网;农业面源污染;水质;河道疏浚;崇明岛;

Abstract: Aiming at the water environment problems caused by insufficient hydrodynamics and the consequent deterioration of water quality in the plain river network of Chongming Island, a study on water resource dispatching schemes for the river network was carried out to improve the hydrodynamic conditions of the river network and the water quality condition.After sorting out the shortcomings of the current water resources scheduling model on the island, measures such as river channel dredging and widening, increasing the drainage channel of the North Lake, and utilizing the current culverts and sluices were selected as the water resources scheduling optimization engineering measures, and we studied their enhancement effect for hydrodynamic and water quality of the river network by constructing a one-dimensional hydrodynamic water quality model of the river network in Chongming Island.We quantitatively analyzed the improvement of the above optimization measures on the pollutant concentration in the characteristic cross section of the river and the renewal rate of the water body.The results showed that: the reduction rate of total phosphorus concentration in some rivers can reach 6.3%～20.1% by river channel dredging and expansion; the water body renewal rate of the river network on the south side increased about 12%～20% by increasing the drainage channel of the North Lake; the use of the existing culverts and sluices on the island for scheduling can comprehensively improve the overall efficiency of the water exchange of Chongming river system, but the upgrading effect through further reconstruction and expansion is limited.

Key words: plain river network; agricultural surface pollution; water quality; river dredging; Chongming Island;