Research On Effect Of Land Use Change Of Hydrological And Ecological Processes In Luanhe River Basin

Land use change is a crucial component of underlying surface variation and environment change,causing the transformation in the hydrological process and structural and function of ecosystem at different sacles.Research on land use and lande cover change and its hydrologic c circulation process and eco-environmental effect is of great importance to basin planning,hydraulic engineering construction and maintenance of ecological security.By researching on upstream area of Panjiakou Reservoir in Luanhe River Basin,the paper makes analysis of land use change and its effect of ecological regionalization,hydrological component,ecological security status and reservoir ecological operation rules,which provides sufficient reference to the decision-making and management of water resource and eco-environmental problems.The main research methods and conclusions are summarized as follows:(1)This paper uses Markov land use transfer matrix and land use comprehensive dynamic degree to analyze the basic characteristics of area changes of the land use type,and uses Kriging interpolation method to analyze the spatial change of land use comprehensive dynamic degree.The results show that the main types of land use in the basin are cultivated land,forest land and grassland,of which the forest land area is the largest,accounting for 37.5%-39.5% of the total area of the basin.The land use type transfer is mainly represented by the mutual transformation between cultivated land,forest land and grassland.The sum of the area of mutual transfer between cultivated land,forest land and grassland accounts for 80.5%-84.5%.In addition,the comprehensive dynamic index of land use respectively reaches highest in the south and north by the degree of spatial distribution at different period of time.(2)This paper selects the regional DEM topographic data,accumulated temperature,precipitation and dryness meteorological data,as well as soil,land use type and NDVI data as the zonation indicators,and uses the sub-basin as the basic zonation unit to divide the basin into five types of ecological divisions.And then this paper uses the land use data of 1970 and 2015 to calculate the ecological zonation distribution of the basin,and analyzes the impact of land use on the ecological zonation.The result shows that the change of land use type with the largest area of cultivated land,forest land and grassland from 1970 to 2015 was the main factor causing the change of ecological division.Changes in land use directly or indirectly affect the spatial distribution of ecological divisions in the basin.(3)In this paper,MWP,Brown-Forsythe,ordered clustering and Lee-Heghinian mutation test are used to analyze the runoff mutation points in hydrological stations.Then the distributed hydrological model is established,and the changes of land use in different phases are selected to analyze the impact of land use conditions on runoff,evaporation and surface runoff.The result show that under the different land use conditions of the hydrological control stations above the Panjiakou Reservoir,the average annual runoff from 1970 to 1990 and 1990 to 2015 shows a downward trend.Changes in land use have led to spatial changes in yield,evaporation,and surface runoff in the study area.(4)This paper establishes an index system of natural,economic and social factors,and studies the ecological security status of the basin through the PSR model comprehensive index method and improved set pair analysis.In addition,this paper uses the land use data of 1970,1990 and 2015,using the grade transfer matrix and Getis-Ord Gi* hotspot analysis to study the impact of land use change on ecological security.The results show that human activities drive the structure and composition of land cover types to change,which makes the ecological level of the basins have large spatial differences.Changes in the pattern of land use types at different phases have led to important changes in the ecological security level of the basin.(5)In this paper,the Phabsim model weighted availability area(WUA)and hydrological statistics are used to determine the minimum and suitable ecological flow of the river.In addition,this paper constructs a reservoir ecological scheduling model,analyzes the water supply scheduling of reservoirs and the available habitat area of carp at different typical years,and calculates the impact of land use change on reservoir management.The results shows that,compared with the Tennant method and 10% of the average annual flow,which is widely used and recognized,it is applicable and reasonable to determine the river ecological environment fow by the biological habitat area.The reservoir ecological scheduling model has greatly improved the river channel's suitable and minimum ecological flow and water supply and the available habitat area of fish.The change of land use has led to the reduction of water supply in cities and rivers in the ecological scheduling of reservoirs,and has affected the changes of fish habitat environment,resulting in the reduction of the available habitat area of carp.