Study On Ecological Restoration And Waterfront Plants Landscape Construction Of Moon Lake In Ningbo City

As a shallow lake in the center of the city,Moon Lake in Ningbo has become increasingly eutrophic in recent years,accompanied by seasonal black odor in some sections,which has greatly reduced its ecological and social benefits.It is urgent to restore its water environment.In conjunction with the ecological restoration engineering,the project carried out water quality monitoring of 10 parameters at 8 sites for 24 weeks to explore the methods of water ecological restoration and waterfront landscape construction.The main results are as follows:(1)Moon Lake has various spatial layers and wingding shoreline,along with excellent waterfront landscape construction conditions.But its overall liquidity is poor and self-purification ability is weak.The shoreline presents typical hardening characteristics,with length ratio of regular revetment and natural revetment about 7:3.The water quality of the lake is not optimistic because of the surrounding domestic sewage,rainwater runoff and nutrient input from the moat.The problems of eutrophication and poor fluidity have been significantly improved through the implementation of ecological restoration measures such as sponge restoration,ecological silt removal,aquatic vegetation reconstruction,operation of the whole-lake flowing water system and artificial blocking salvage.(2)The results of water quality monitoring show that after the operation of the whole lake's living water system and hydrophytes entered a period of vigorous growth,which strengthened their ability of water purifying and the decomposition of rhizosphere microorganisms,the water transparency increased by 0.46 m on average,the concentration of total nitrogen and total phosphorus decreased by 1.74 mg/L and 0.17 mg/L respectively,the chlorophyll a concentration decreased by 70.12 mg/L compared with that before operation,and the growth of organic pollutants and algae was obviously controlled.Furthermore,the water quality of the sites with better exchange,higher coverage of aquatic vegetation and fewer surrounding buildings tends to be better.The average value of nutritional status index decreased from 68.8 to 58.6,which reflects that overall eutrophication degree of the lake was reduced from medium-heavy to light-medium level by implementation of engineering.(3)The aquatic ecosystem restoration engineering impeled the hydrophytic community to recover gradually such as Vallisneria natans,Iris pseudacorus and Canna indica,combining with reasonable community configuration of terrestrial plants,constructed waterfront plant landscape according to the different waterfront space.Combination of “colorful leaves and flower shrubs + hydrophyte” was used to soften the hard straight shoreline,high and low scattered trees such as Melia azedarach,Sapium sebiferum and Metasequoia glyptostroboides were used to enrich the canopy line,and the bird-attracting species like Pyracantha fortuneana and Ilex cornuta were used to increase the diversity of lakeside animal landscape.All of the above form a transitional zone of terrestrial and aquatic plant communities,and ultimately achieve the dual effects of restoration of damaged lake ecosystem and visual enhancement of waterfront landscape.