Ecological Restoration Engineering Integrated Technology Of River In Plain Lake Area

In river network concentration areas of our country,farmers are used to living along the river,domestic sewage,aquaculture waste water,and agricultural water is discharged directly as soon as possible without being treated.In addition,in the past 40 years,due to the rapid economic growth and the improvement of people’s living standards,the trend of water ecological function and water environment degradation has become more and more intense,outstanding performance in the water quality decline,water blackening eutrophication is obvious,water body self-purification ability decreases,ecosystem structure and function disappear.,which make plain lake river ecological degradation and water pollution,ecological restoration are playing a more and more difficult.This paper selects the typical river-Yuanmi River of plain lake area as the study area and under the guidance of the"Near-natural,high-effective,multi-functional,sustainable"as ecological restoration concept.And the stage goal is’Contain water pollution,improve water environment,strengthen self-purification capacity,improve ecological function.This study employs integrated technologies including riparian vegetation buffer zone,artificial biological floating island,ecological pond-shoal,shoal-biofilter.And on the basis of evaluation and analysis of ecological diversity,water quality status and pollution sources of the Yuanmi River,by doing the engineering design,construction and investigation on water quality,biodiversity and ecological function of river after construction.It constructed the initial ecological restoration engineering integration technology of water body pollution suitable for rivers in plain lake area.The main conclusions are as follows:（1）Before implementation of ecological restoration project,Through on-the-spot investigation of the Yuanmi River,The results show that:The water has pungent smell,water quality pollution is mainly characterized by eutrophication and blackness,high concentration of COD、TN、TP,the water quality is inferior classⅤ,has lost its functions which including drinking water and irrigation.The pollution source of the river is mainly from the rural areas,and rural and agricultural pollution contribute 87.81%to the total water pollutants.The first pollution source of Yuanmi River is rural domestic sewage from non-point source pollution,accounting for 49.74%;followed by livestock pollution,accounting for 30.24%;the third is the urban domestic sewage,accounting for 7.43%.（2）Taking into account the impact of organic pollution on the Yuanmi River,we build and implement an ecological rehabilitation project which assembles riparian vegetation buffer zone,artificial biological floating island,ecological pond-shoal,shoal-biofilter.According to the survey data,odour decrease clearly and the phenomenon of blackening be improved to a certain extent about Yuanmi River after completion of project implementation.And the number of riparian plant species was from the initial 11 to 28,aquatic plant species was from 8to 15,bird and fish species was from 10 to 21,vegetable and fruit was from 3 to 12,riparian vegetation coverage rate reach more than 80%.At the same time,ecological ponds change the single state of fish structure,improve fish yield and quality,flowers and garden stuffs from floating islandbring other additional economic benefits to the residents.In addition,these measures such as riparian vegetation play a role in beautifying landscape,increasing biodiversity and improving surrounding habitats.（3）By monitoring water quality before and after construction,datas show that after the river has been regulated,TN、TP、TN、COD_Cr、NH₃-N of water body decreased significantly,DO has a marked upward trend。In the construction section,the average TP、TN、COD_Cr、NH₃-N decreased from 1.60 mg/L,2.625mg/L,49.75mg/L,1.49mg/L down to 0.85mg/L,1.27mg/L,29.81mg/L,1.02mg/L,as the same time,the average of DO rose from2.07mg/L to 3.98mg/L.And without considering other external factors,the decrease rates of TP,TN,COD_Cr,NH₃-N in the whole water body were respectively 46.88%,51.62%,40.08%,30.61%,the increase rate of DO was 92.27%,and the overall water quality is gradually recovering from inferior classⅤto classⅣ.As a result,the water quality improved effectively because of the demonstration project,and the feasibility of the integrated technology of ecological restoration engineering is verified.（4）the integrated technology of river ecological restoration project implemented in this paper can not take measures to reduce the source of pollutants in the river basin,but also reduced the content of TP,TN,COD_Cr,NH₃-N in the river and increase the content of DO in the river.And the number of coastal plants,aquatic plants and fish species has increased,the landscape of the river has been improved,and the water quality of the demonstration project has been effectively managed and gradually improved.From the whole research area,the demonstration project has a good effect on the water quality of the river in the plain lake area,and can provide some technical support and demonstration for the ecological restoration of the river environment in the plain lake area.