Construction And Application Of Yitong River Habitat Quality Assessment (Y-RHA), Near Changchun City

River ecosystems around the world have taken place in different degree of degradation during the past decade.As an important component of river ecosystem,river habitat is the important basis of river health assessment and management.As a result,the river habitat quality assessment has the vital practical significance.The paper comprehensively summarized the theoretical basis and experience of riverhabitat quality evaluation.On the basis of the most representative river habitat quality evaluation systems: Rapid Bioasscssment Protocols of United States,River habitat survey of United Kingdom and An index of stream condition of Australia,together with the present situation of Yitong river habitat and characteristics.Yitong river habitat quality assessment?Y-RHA?framework has been determined,which involves riparian habitat characteristics,channel characteristics,disturbance of human activities.Screening out 10 indicators: bank stability,width of riparian zone,structure of riparian vegetation,types of revetiment,water volume,water quality parameter,river sediment composition,channel connectivity,hydrophyte,land use type.The habitat survey was taken in July 2014,October 2014,July 2015,October 2015,seclecting 16 monitoring of the river.Different types of river habitat are endowed with different scores,river habitat quality comprehensive index?Y-RQI?.The evaluation results show that:?1?Y-RQI of wet season is 90.97,belongs to the general level.The ROI of 16 monitorings is beween 3.47-8.47.The number of general monitoring level is 6.The number of good monitoring level is 4.The number of best monitoring level is 3.The number of bad monitoring level is 3.There's no worst monitoring level.?2?Y-RQI of normal water period is 62.41,belongs to the general level.The ROI of 14 monitorings is beween 2.02-7.18.The number of general monitoring level is 6.The number of bad monitoring level is 5.The number of good monitoring level is 3.The number of worst monitoring level is 1.There's no best monitoring level.?3?Analysis of Yitong different segments' habitat quality differences and factors.We can see that the habitat quality index of source and ecological engineering region is higher than other regions.The habitat quality index of rural and urban region is relatively low.The habitat quality index of town region is between rural and urban region.Yitong habitat quality problems are mainly reflected in 5 aspects:?1?Riparian zone space pending is redevelopment.Yitong overall health of riparian zone space gets vandalism and interferences.?2?River bank protection types need to be improved.There's a lot exposed soil banks without the presence of vegetation and Artificial stepped revetment or vertical reinforced concrete revetment which is concentrated in urban region.These phenomena cause revetment channels and homogenization.?3?Water pollution of wet season is serious.NH₃-N is a Class V water in the 6 monitoring sites from monitoring 10.COD_Cr?BOD₅ is a Class V in 4 monitoring sites.Water pollution of normal water period is worse than wet season'.?4?Channel connectivity is poor.The average index of 2 regions' channel connectivity?C8?is 0.34.The channel connectivity of 4 monitorings is severely damaged.?5?Yitong is in serious interference by human activities.The average index of landuse?C10?is 0.24.We can see that there are a lot of land use types,which is a serious damage to Yitong.Suggestions and advice for Yitong habitat quality problems are given as follows:?1?It suggests strengthening the management of riparian zone spacerural of Yitong's rural and urban region.The area and extent of land development should to be appropriately restricted.?2?We recommend to control of water quality of discharged waste water strictly.Reducing emissions from domestic sewage,industrial waste water.Using biofilm methods to control water pollution in the middle and lower reaches of river basin.?3?Yitong revetment should to be repaired.Building natural soil slopes with vegetation cover or close to natural ecological sloping revetment.