Study on the effect of urban river environmental dredging and hydraulic dredging:taking Xuejiabang, Liangtang River of Wuxi as an example

In view of the serious endogenous pollution in Xuejiabang, Liangtang River of Wuxi City, two dredging methods, including environmental dredging and hydraulic dredging, were applied to evaluate the effect of dredging on the reduction of endogenous pollution in river by studying the changes of total nitrogen and total phosphorus in sediment and water before and after dredging, and the static release flux from the sediment. The results showed that the two dredging methods could effectively reduce the nutrient contents in the sediment. After environmental dredging, the total nitrogen and total phosphorus concentrations were reduced by 46.50% and 35.51%, respectively, and after hydraulic dredging, the total nitrogen and total phosphorus concentrations were reduced by 40.10% and 30.51%, respectively. But to achieve the same dredging effect, hydraulic dredging would lead to an increase in the amount of work compared with environmental dredging. On the premise of better control of exogenous pollution, both the two dredging methods could effectively reduce the pollution caused by endogenous release to water. The nitrogen and phosphorus release flux reduction rate of environmental dredging was higher with 46.92% and 38.53%, respectively, while that of hydralic dredging was 40.99% and 30.09%, respectively. In view of the shortage of land resources in urban areas, the problem of easy over-digging by hydraulic dredging and the difficulty in recovering the water ecosystem after dredging, it was suggested to adopt the environmental dredging method to solve the problem of the internal pollution of urban river courses.