Research On The Method And Application Of Differential Environmental Flow Definition Of Rivers In The Shaying River Basin Of Henan Province

The concept that the environment is a legitimate user of water has been accepted by governments and scholars.Environmental flow is an important reference for basin water resources management and a key factor for river ecological protection.Scientific definition and calculation of river environmental flow is to ensure the river ecosystem An important prerequisite for health and sustainable development.The Shaying River Basin has extremely high water resources pressure and severe human disturbance,which has led to various water pollution and water ecological degradation problems among rivers in the basin.Starting from the diversified problems faced by rivers in the Shaying River Basin,this research carried out research on the classification of river basins,the composition of various types of river environmental flow and calculation methods,proposed a method for determining the differential environmental flow of rivers in the basin,and calculated the environmental flow threshold of typical rivers,And analyze the corresponding environmental traffic protection measures.The main research contents of the thesis include:(1)Based on the status quo of hydrology,water conservancy,and aquatic ecological environment,analyze the various water ecological environmental problems faced by rivers in the basin,and divide the rivers in the basin into three types: basic flow scarce type,water quality guarantee type and near-natural type based on the problem.The type of river is judged step by step.The distinguishing factors for the lack of base flow are the frequency of river dry-up and the guarantee rate of ecological water demand,and the distinguishing factor for the guarantee of water quality is the proportion of the river length that does not meet the standard.(2)The differentiated environmental flow composition of the three types of rivers was defined,and the corresponding applicable calculation methods were determined through comparison.For rivers with poor base flow,choose the monthly frequency method to calculate the minimum ecological water demand of the river,and use the monthly guarantee rate method with a 25% guarantee rate to calculate the basic flow of the river;the water quality guarantee river chooses the first section and tail control method to calculate the self-purification and pollution-receiving requirements Select the monthly guarantee rate method with a 50% guarantee rate to calculate the basic ecological flow of the river;select the IFIM method to calculate the environmental flow required during the breeding period of the protection target for the near-natural river,and use the monthly frequency method of the minimum ecological runoff to calculate the required growth period Environmental flow.(3)The Fenquan River,Jialu River,and Beiru River are selected as typical rivers of various types to carry out the application of differentiated environmental flow definition methods.The baseline flow-scarce Fenquan River has a monthly environmental flow target of 1.56～4.67m~3/ s(monthly guarantee rate method grade IV and 10% multi-year average runoff),the long-term environmental flow target is5.29～18.50m~3/s(monthly guarantee rate method grade II and monthly frequency method);the water quality guarantee type Jialu River in recent months The environmental flow target is 2.40～4.18m~3/s(monthly guarantee rate method grade IV),and the long-term environmental flow target is 18.38～37.28m~3/s(section head and tail control method);the near-natural Beiru River is based on horsemouth fish 、Cabbage fish is a protected fish.The environmental flow target in the breeding period(March to August)is 13m~3/s(IFIM method),and the environmental flow target in the growth period is 1.42～43.01m~3/s(Monthly Guarantee Rate Method Level IV)).