The Research Of The Ecological Hydrological And Water Quality Effect In Watershed Of Baiyian Creek,Maoli Lake,Jinshi City,Hunan Province

In this thesis,the watershed of Baiyian creek,Maoli Lake,Jinshi City,Hunan Province was taken as the research object,data information was collected by field surveys and searching for literatures,SWAT model software was used to establish the hydrology and water quality model of Baiyian creek Basin,simulate the status quo,three different vegetation types extreme scenarios and three ecological restoration plans of reasonable scenarios of the one-year eco-hydrological water quality effect,the differences in the improvement of water quality and hydrological quality covered by different vegetation types were analyzed.The main contents included the impacts of different types of vegetation cover in the river basin on runoff(surface runoff,groundwater runoff),sediment yield,and total nitrogen load,and total phosphorus load,and through the comparative analysis of the ecological benefits of different ecological restoration programs,choosing the optimal,practical and feasible program,providing the basis for the basin planning and design.The results showed that the eco-hydrological water quality effects of different vegetation cover types were different.In the basin,the forest land can exert good ecological benefits in all aspects,especially the evergreen forest,followed by mixed forest.The shrubbery’s ability to conserve water sources is not significantly different from that of the forest land,and it has the advantages of low cost and easy survival.Mixed wetlands have outstanding performance in ecological water quality effects,especially in sediment yield and total phosphorus load second to those of forest land.Therefore,ecological restoration of basin can focus on forest land construction,combine forests and shrubbery in water conservation lands,and combine forest lands with mixed wetlands in lakes and rivers to comprehensively improve overall ecological environment of the basin.The multi-measurement analysis of variance method of SPSS software was used to perform a significance test on the ecological benefits under different land use/vegetation cover scenarios.The results showed that the runoff and sediment yield were significant,demonstrating that the extreme scenarios and reasonable scenarios would significantly improve the functions of water conservation and regulation of runoff of the watershed systems and ecosystems.Organic pollutants such as organic nitrogen,organic phosphorus,and mineral phosphorus were closely related to the amount of soil loss.Thus,soil loss directly reflected organic nitrogen load,organic phosphorus load,and mineral phosphorus load.Therefore,the extreme scenarios and reasonable scenarios studied in this thesis can reduce total nitrogen load and phosphorus load to some extent.In the thesis,based on the status quo of the Baiyian creek Basin,the ecological restoration plan T1 of the planned basin was carried out,adjustment on the basis of T1 was performed,thus T2 and T3 were obtained(reasonable scenarios).Also the SWAT models for hydrological and water quality simulation prediction were established,respectively.From the data analysis of the average ecological and hydrological water quality effect of the simulated watershed,the simulation results of T3 indicated,with the surface runoff depth of 37.79mm,a decrease of 32.85%from the current situation,the groundwater runoff of 486.67mm,an increase of 3.26%over the current situation,the sediment yield of 4t/hm2,a decrease of 48.78%from the current situation,the total nitrogen of 49.619kg/hm2,14.98%lower than the current situation,the total phosphorus load of 0.79 kg/hm2,36.50%lower than the current situation.The decrease or increase ratio of each index is 1.33%,0.34%,1.15%,0.10%,0.81%higher than that of T1,which is 2.80%,0.50%,2.05%,0.24%,1.61%higher than that of T2.Among them,T3 had the best ecological benefits,followed by T1,and the T2 is relatively weak.On the basis of the planning ecological restoration scheme T1,the T3 will exchange the mixed forest and the evergreen forest.Without considering the construction cost and levies agricultural lands,T3 is the best and feasible recovery scheme for the ecological benefit.