| Based on a large number of literatures based on the extraction of hydrological features and the relationship between hydrological features and landform development based on digital elevation models(DEM)or traditional paper data,this dissertation refers to the digital blue line water system of 1:50 million topographic maps as a reference,Using the current ArcGIS 10.2 and Arc Hydro Tools technology based on DEM to extract or estimate hydrological feature values to extract 20 m DEM,30 m DEM,90 m DEM water systems,and extract the water system from the optimal threshold based on river network density and confluence threshold,The relationship between the density of the river network and the threshold of the catchment area determines the optimal confluence threshold of the dam construction area of the Karst Qianzhong Water Control Project;the Horton theorem method,the grid method of the water system,the fishnet method(Fishnet)and the fluctuating ratio method of the watershed(the integrated value of elevation HI)systematically evaluate the suitability of the method for determining the stage of landform development in the Karst dam basin,with a view to using the DEM digital elevation data and ArcGIS 10.2,Arc Hydro Tools and other technologies to quantitatively study the grids of fishing nets constructed by ArcGIS technology.Estimate the watershed fractal dimension and watershed relief ratio(elevation integral value HI),quantify the watershed landform development stage determined by the fishing net raster and estimate the water system fractal dimension value and watershed relief ratio value(elevation integration value HI)A comparative study was conducted to explore the feasibility of judging the development stage of watershed geomorphology based on the ArcGIS technology in the Karst area to construct the grid of the water system fishing net and estimate the fractal dimension of the water system.In-depth analysis of domestic and foreign research results,this paper based on ArcGIS technology DEM extraction of hydrological characteristics and quantitative research on the relationship between hydrological characteristics and landform development,the following new understanding and new progress.Under the reference of 1:50,000 water systems,it is proposed to extract water systems from different scale DEMs such as 20 m DEM,30 m DEM,90 m DEM,etc.Based on the trial and error method,set the cumulative accumulation threshold at 500 intervals,using ArcGIS 10.2 Research on extraction of grid confluence thresholds from 500,1000,1500,2000,2500,3000,3500,4000,4500,5000,5500,6000,6500,7000,7500,8000,8500,9000,9500,10000 The water system of the district river network,through the use of technical drawing and statistical software such as EXCEL,Oringin9.1,and statistics of each grid confluence threshold to extract the relationship between the density of the river network,the total length of the river,the number of rivers and the set confluence threshold,and then through the analysis River network density,total length of rivers,number of rivers,and inflection point change trend of set confluence threshold curve to determine the best confluence threshold;in addition,based on Arc Hydro Tools set a series of watershed area threshold thresholds to establish different watershed areas The relationship between the threshold and the density of the river network determines the optimal threshold for the catchment area.Finally,the ArcGIS 10.2 hydrological analysis tool and Arc Hydro Tools are used to extract the grid flow threshold of the water system,and the optimal threshold of the water system based on the DEM of different spatial resolutions at the 1:50000 topographic map of the Karst area is determined.Finally,using the DEM of 20 m spatial resolution as the basic data source,Arc Hydro Tools software was used to extract the water system of the study area based on the optimal threshold,and the spatial distribution and evolution characteristics of the river network water system in the study area and its topography,landform and geology were further analyzed.Lithological relationship.Based on the optimal threshold extraction water system,Horton's theorem method,water system grid method,fishnet method(Fishnet)are used to estimate the fractal dimension of the best water system with different resolution DEM,and discuss the different scale water system fractal dimension and the dam engineering area.The relationship between watershed landform development.By using DEM of different scales in each watershed of the dam construction area as the basic data source,using ArcGIS 10.2 software to calculate the maximum elevation,minimum elevation,and average height of each watershed,and finally estimate the integrated elevation value(HI)of each watershed according to the fluctuation ratio method Finally,the HI value is used to determine the stage of landform development in each watershed in the study area,and then compared with the landform development stage revealed by Horton's theorem,water grid method,and fishnet method through the fractal dimension of the water system to determine the various methods for karst The suitability of judging the stage of landform development in the dam basin.This article takes the dam area of Qianzhong Water Control Project as the research sample area,takes the digital water system of 1:50 million topographic map as reference,uses 20 m DEM,30 m DEM,90 m DEM as data sources,and uses ArcGIS 10.2 and Arc Hydro Tools software Extract the optimal confluence threshold and catchment area threshold in the study area.Based on the optimal threshold extraction water system,Horton's theorem method,water system grid method,fishnet method(Fishnet)are used to estimate the fractal dimension of the best water system with different resolution DEM,and discuss the different scale water system fractal dimension and the dam engineering area.The relationship between watershed landform development.The main conclusions of this study are as follows:(1)Using the spatial resolution DEM of 20 m,30 m and 90 m and the reference water system of the 1:50000 topographic map as data sources,using ArcGIS 10.2 and Arc Hydro Tools,a 1:50000 topographic map of different spatial resolution DEM was carried out The optimal threshold value of water system extraction at the scale of extraction water system is analyzed,and the optimal confluence threshold value for extracting the DEM hydrological characteristics of Karst area at this scale is 1500.(2)Using 20 m DEM as the data source,combining ArcGIS 10.2 and Arc Hydro Tools,and extracting the water system of the water system research area based on the best confluence threshold 1500 of appeal,construct a 10km×10km fishing net grid in the research area and carry out each fishing net grid Coding to find the unit grid river network density of each fishing net grid,and to explore the relationship between the spatial distribution of the fishing net grid river network density and the geological and geomorphic response of the study area.The area is basically located in the central and eastern part of the study area,with complex tectonic activities(basin),peak forest valleys,peak cluster valleys and local peak cluster depressions in the southwest and northeast,and Permian and Triassic strata in the central and eastern regions.The most widely distributed Karst distribution area.(3)Using the spatial resolution DEM of 20 m,30 m and 90 m and the reference water system of 1:50,000 topographic maps as data sources,using ArcGIS 10.2 and Arc Hydro Tools to carry out the DEM of different spatial resolutions at 1:50000 The topographic map refers to the optimal confluence threshold 1500 at the scale of the water system to extract the water system,and discusses the hydrology and Arc Hydro Tools hydrogeographic analysis technology based on ArcGIS 10.2 respectively,and uses the classic traditional method of judging the development stage of landforms as the verification of the fluctuation ratio(HI),Discuss the Horton-Strahler method,water grid method,and fishing net method to estimate the fractal dimension of the Karst watershed and its relationship with the landform development stage.Through analysis,we can get the method of extracting the estimated fractal dimension of the water system based on DEM in the Karst area.Horton-Strahler The error rate of the method is higher,and the result of judging the development of the watershed geomorphology is quite different from the real situation.The results of the watershed landform development stage estimated by the fishing net method are the same as the results of the classical method of undulation ratio(HI),and the results obtained by the water grid method are second to the fishing net method.Through comparative analysis,it can be concluded that the fishnet method is feasible in the method of extracting the estimated fractal dimension of the water system based on DEM in the Karst area. |
PDF Full Text Request