| In order to meet the needs of irrigation,storage of water resources,drainage,flood control,and shipping in plain areas,people have artificially rebuilt or rebuilt the original water system.In the past period of time,the artificial reconstruction of rivers generally fo-cused on the functions of river diversion,drainage,storage,navigation,etc.,which exerted greater social and economic benefits.However,the artificial reconstruction has played a major role in maintaining the ecological environment in the region.Insufficient considera-tion of ecological functions such as balancing and regulating the microclimate in the region.Some rivers no longer meet the requirements of high-quality development and ecological civilization construction.It is necessary to carry out ecological transformation of artificial rivers.In ecological transformation,it is necessary to grasp that "landscapes,forests,fields,lakes and grasses are a The scientific connotation of "Community of Life" comprehensively considers various water requirements inside and outside the river,aquatic organisms,and terrestrial plants,defines the ecological functions of the river,determines the ecological wa-ter level,and calculates the ecological water demand.On the basis of combing the relevant theories and calculation methods of ecological water demand at home and abroad,this paper proposes a method that considers the mainte-nance of normal vegetation in the river block in order to solve the problem that the existing methods are not applicable to the ecological functions of the highly artificial rivers in the plain area.The calculation method that meets the needs of ecological services in Hanoi is the key to the growth requirements,and the method is applied to calculate the ecological water demand of the plain rivers in the high sand area in the south of Jiangdutong,which is the calculation of the ecological water demand of the highly artificial rivers in the plains.A useful exploration.The research results are as follows:(1)Study the connotation of ecological water demand of highly artificial rivers in plain river network areas and the protection goals of artificial rivers.Combining the characteris-tics of the plain area,comprehensively analyze the existing concepts of ecological water demand,and give the connotation of ecological water demand used in this study,namely,the ecological water level and ecological water level and ecological water required for the health of rivers and lakes,meeting water quality requirements and meeting ecological needs flow.Through the evaluation and analysis of the regional river ecology status,it is found that in terms of natural functions,the river has insufficient biodiversity and serious water pollution;in terms of social functions,problems such as poor river connection and poor landscape environment.Based on this,the goals of ecological protection are clearly defined as:ensuring the aquatic habitat,replenishing groundwater,ensuring the normal growth of vegetation in river plots,ensuring landscape entertainment,shipping,maintaining the flow-ability of the river,and the need for water in such areas as river self-purification.(2)Research on the calculation method of river ecological water level for replenish-ment of groundwater by the river to ensure the normal growth of vegetation in the river block.By analyzing the relationship between the growth of vegetation roots and the depth of groundwater level,it is determined that the suitable and limit ecological groundwater levels of typical vegetation are 2.5m and 3.0m,respectively.According to the recharge rela-tionship between the river and groundwater,the relationship between the groundwater level and the ecological water level of the river is established,and the ecological water level of the river is 2.1m calculated by the mathematical model of the steady movement of diving.(3)Research on calculation of river ecological water level that meets the requirements of water depth.The rivers in the river network of the study area are interconnected.Accord-ing to the river elevation of the study area,the minimum water depth for aquatic organisms and the minimum water depth required by the navigable landscape are analyzed as the basis for the ecological water level of the study area.It is calculated that the functions of main-taining aquatic habitat,ensuring navigation functions,and landscape entertainment func-tions are 2m,1.5m,and 1.5m,respectively.According to the above three protection goals,the ecological water level of the river channel that meets the water depth requirement is 2m,and all the protection goals are integrated.The calculated result takes the outer line to de-termine the ecological water level of the river channel to be 2.1m.(4)Calculation of the ecological flow of the Baita River in the artificial backbone of the plain area.First,calculate the ecological flow required for the self-purification of the river.According to the actual situation of the Baita River,use MIKE11 to simulate the arti-ficial river course in the plain area to obtain the current year(2020),the wet year(2003),and the normal year(2007).And the self-purification ecological flow in the dry year(2001)is 0.6m3/s,0m3/s,1.5m3/s and 2.8m3/s respectively.In order to ensure a good ecological en-vironment in Baita River,the dry annual water volume should be used.And water quality as the benchmark,that is,the ecological flow of the river channel that reaches the key river Baita River’s water quality target is 2.8m3/s.On the other hand,considering the maintenance of the connectivity of the artificial river network in the plain,biological habitat,landscape entertainment and other functions to calculate the ecological flow,it needs to be determined according to the control section parameters of the river,the ecological water level and the flow velocity.Among them,as the key factor,the ecological flow rate for fish breeding is 0.1m/s.According to the formula,the ecological flow rate during the fish breeding period in Baita River is 10.3m3/s,which can basically maintain the water required for normal fish breeding.Claim. |
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