| The Wei River is the largest tributary of the Yellow River,and its governance and development play an important role in the healthy development of the Guantian Economic Zone.The Wei River Basin is a relatively water scarce area.The main cause is resource-based water shortage.Since the beginning of the 21st century,the rapid development of society and economy has led to excessive exploitation of water resources.Serious ecological and environmental problems such as water shortage,water quality pollution,and river siltation have occurred in the Wei River Basin.In order to restore the ecological health of the Wei River Basin,when developing and utilizing water resources,in addition to considering production and domestic water use,the environmental flow of the river must also be considered.On the basis of summarizing the research results of environmental flow at home and abroad,this paper summarizes the related concepts of environmental flow and elaborates the research progress of its calculation methods.Taking the Wei River Basin as the research area,12 research sections were set up in the Wei River,Jinghe River and Beiluo River,and the environmental flow calculation model was established.The environmental flow optimization calculation and guarantee rate analysis were performed to restore water ecology in the basin and optimized allocation to provide scientific basis for water resources.The main research results are as follows:Based on the ecological and environmental characteristics of the Wei River,Jinghe River and Beiluo River,the ecological types of the rivers were divided.Based on the improved ecological hydraulic radius method,the annual average environment flows of 12 sections of the Wei River,Jinghe River and Beiluo River were calculated.Each section was selected.The minimum value of the dry season(December-March)is used as the recommended value of environmental flow.The environmental flows of Wei River Beidao,Linjiacun,Weijiabao,Xianyang,Lintong and Huaxian are 5.68m3/s,2.51m3/s,11.39m3/s,25.33m3/s,77.26m3/s and 61.86m3/s.The environmental flows of Yangjiaping,Yuluping and Zhangjiashan sections of Jinghe River system are 7.74m3/s,4.05m3/s and 9.64m3/s,while those of Liujiahe,Jiaokouhe and Zhuangtou sections of Beiluohe River are 2.80 m3/s,10.96 m3/s and 8.52m3/s.The maximum value of the environmental flow in each section is concentrated in the flood season(July to September),and the minimum value is concentrated in the dry season(December to March).The environmental flow of each section of the same water system has the same trend in each month.The Lintong and Huaxian sections showed significant peaks during the flood season,and the maximum environmental flow appeared in July and August,respectively.The environmental flow of the Jinghe River in the flood season is Zhangjiashan,Yangjiaping,and Yuluoping.The maximum environmental flow of Zhangjiashan appears in July in the flood season and the minimum appears in March in the dry season.The environmental flow of each section of the Beiluohe River system varies greatly in different months.The peaks of the environmental flow of Liujiahe,Jiaokouhe and Zhuangtou all appeared in July in the flood season.Based on the improved ecological hydraulic radius method,the annual and monthly average environmental flow of the 12 sections of the Wei River,Jinghe River and Beiluo River were calculated.The environmental flow is different,and the monthly environmental flow in the flood season is higher than the non-flood season.By comparing the calculation results of environmental flow in different horizontal years of Beiluo River and Jinghe River,it is found that the value of environmental flow in flood season in different levels of Beiluo River system is obviously higher than that in Jinghe River system.According to the formula of the environmental flow guarantee rate,the monthly environmental flow guarantee rate of the 12 sections of the Wei River,Jinghe River and Beiluo River was calculated.Except that the average daily flow of the Beidao section in October can meet the requirements of the environmental flow,the other sections cannot meet the requirements of the environmental flow in each month,and there is a significant difference in the monthly rate of environmental flow in different months of each section.Except for the Linjiacun section of the Wei River,the other sections of the Wei River have a higher monthly rate of environmental flow during the flood season,a lower rate of protection during the non-flood season,and the problem is most prominent during the dry season.On the other hand,the sections of the Jinghe River and Beiluo River have higher monthly guarantee rates for the environmental flow in the non-flood season,and lower monthly guarantee rates for the environmental flow in the flood season.According to the formula of the environment flow guarantee rate,the monthly basement guarantee rate of the environment flow in the 12 sections of Wei River,Jinghe River and Beiluo River with different levels of abundance,flatness,and dryness was calculated.The year is the lowest,the annual rainfall and annual runoff are high,and the guarantee rate is higher,which is consistent with the actual situation.By comparing the calculation results of the annual environment flow guarantee rates at different levels in the Beiluo River and the Jinghe River,it can be found that the average environment flow guarantee rate of different levels of abundant,flat,and dry seasons in the Beiluo River system is significantly lower than that in the Jinghe River.Based on the analysis of the guarantee rate of environment flow in Wei River Basin,the shortage of environment flow in Wei River Basin is serious,and the following measures are put forward:through rational use of water resources,adopting agricultural water saving,industrial water saving and urban water saving,can alleviate the shortage of water;Through the use of ecological water regulation and control methods such as joint operation of reservoirs,inter-basin water transfer,construction of regulation and storage projects,and strengthening the control and management of water resources,the sustainable guarantee of environment flow is realized,and the environmental and economic benefits of water resources utilization are adjusted to restore and improve the environmental health of the river. |
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