滆湖重建沉水植物生境对抑制沉积物再悬浮的模拟研究OA北大核心CSTPCD

Lake Gehu,the second largest shallow lake in Taihu Basin,has undergone rapid water environment changes since the 1990s,with almost total loss of aquatic plants and the changing of ecological type from"macrophyte-clear"to"algae-turbid".The sediment in this type of lake tends to suspend induced by strong wind,hence,recreation of submerged plants community was recog-nized to be one of the valid measures for restoring ecological environment in Lake Gehu.In this article,an environmental model was developed,to investigate the hydrodynamic process and sediment resuspension.Results show that,under normal wind condition(2.2-2.8 m/s),the mean value of bed shear stress of the whole lake is about 0.023 N/m2,which cause no sediments resuspen-sion.However,this value can reach over 0.45 N/m2 under extreme wind condition(＞10 m/s),and sediment resuspension proba-bly occurs in the most parts of the lake.The southern shallow area and its east and west coast are the high-frequency areas where sediment resuspension occurs.A scenario of reconstructing submerged plant habitat in the area prone to sediment resuspension and suitable for plant growth(covering about 12％of the whole lake)was set for prediction analysis.The results indicate that,under scenario condition,the average annual bed shear stress of the whole lake reduced 24.4％and thus 29.3％and 25.1％for suspended solids concentration both in annual average and at the moment of strong wind,respectively.During a strong wind in simulation,the mean bed shear stress of the whole lake decreased from 0.45 to 0.34 N/m2 compared with the actual situation,and the mean and maximum concentrations of suspended solids decreased by 20.9 mg/L and 470 mg/L,respectively.The presence of submerged plant habitat is capable of significant reducing the concentration of total suspended solids in the lake.