生态调度控制汉江中游入侵沉水植物过度生长效果研究OA北大核心CSTPCD

Overgrowth of the invasive submerged plant,Elodea nuttallii,in the middle reaches of Hanji-ang River(from Danjiangkou to Wangfuzhou)has adversely effected native aquatic plants and biodiver-sity.Based on the observed relationship between extreme changes in spring flow and E.nuttallii over-growth,experiments on ecological scheduling of flow were conducted in Danjiangkou Reservoir and Wangfuzhou Reservoir to control E.nuttallii overgrowth for two consecutive years,2020 and 2021.We evaluated the effect of ecological flow regulation based on continuous monitoring of water velocity and flow,and E.nuttallii biomass and distribution area.Results show that:(1)In the section from Danjiangkou to Wangfuzhou,there was 16.8 km2 of water area suitable for E.nuttallii growth,distributed primarily in the shallow waters on both sides above the dam,the upper beach of the sluice gates,Shuianxincheng Is-land and Zhongzhou Island,Mupaigang and Yangpitan.(2)The biomass of E.nuttallii peaked in July and August,at 4.80×104t,1.30×104t and 0.58×104t,respectively,in 2019,2020,and 2021 and the respective distribution areas of E.nuttallii were 11.60 km2,2.02 km2 and 0.87 km2.Ecological flow regulation de-creased E.nuttallii overgrowth significantly with biomass and distribution area decreasing each year.The annual peak biomass of E.nuttallii was negatively correlated(r＞0.9)with both the ratio of extreme flows during the spring germination period(January to March)and the average flow in the vigorous growth peri-od(April to August).The correlation coefficient between annual peak biomass of E.nuttallii and the annu-al average flow(r--0.748),as well as with the average water temperature(r=0.732),were greater than 0.7.Discharge(velocity)and water temperature were the key factors affecting E.nuttallii biomass.(3)Based on the daily harvest of floating E.nuttallii and the inflow to Wangfuzhou Reservoir,we recom-mend an inflow(i.e.,the release from Danjiangkou Reservoir)not less than 1 500 m3/s to carry away ma-ture agglomerates of E.nuttallii,and a single peak flow of 3 500 m3/s to reduce E.nuttallii biomass in the study area by about 40％.