Evaluation of Restoration Effect of Submerged Plant Community in Urban Rivers Replenished by Reclaimed Water

Abstract

Submerged plant community construction is extensively used in the field of urban river ecological restoration, but it is sometimes difficult to establish a large area of survival or a stable community after restoration. Therefore, there is some uncertainty in determining the restoration effect. To verify the restoration effect of urban rivers replenished by reclaimed water through the application of a submerged plant community, this paper takes the typical urban rivers with reclaimed water in Beijing, the Liangshui River and the Dalong River, as the research objects and takes the Yongding River, a river replenished by natural water, as the comparison to establish a water eco-environment quality index and carry out the restoration effect evaluation of a submerged plant community based on field monitoring. In a comparison of the water eco-environment quality index of rivers and the coverage of submerged plants, the evaluation results indicate that the Yongding River and Liangshui River have the same number of submerged plant species, yet their plant coverage is different. The ecological environment quality condition of the Yongding River is superior to that of the Liangshui River and the Dalong River. The ecological environment quality of the reclaimed water river segment with an average coverage of submerged plants greater than or equal to 50% is relatively better, with relatively more sensitive species. This suggests that for rivers replenished by reclaimed water, the construction of submerged plant communities will improve the water ecological conditions on the premise of ensuring a certain degree of submerged plant species and coverage. By calculating the correlation coefficients relating to the coverage of submerged plants by 32 environmental factors including the indicators of water quality, hydrology and sediment, the paper initially screens out water depth, ammonia nitrogen, nitrite nitrogen, BOD, permanganate index, and total nitrogen and organic carbon in the sediment as the major environmental factors affecting the coverage status of submerged plants. It can provide a reference for the control of environmental factors in the construction and maintenance of submerged plants to guarantee a restoration effect in the future.