Study On Spatial Information Model Of Watershed Ecological Environment Risk Management In Xishan Coal-related Industry Agglomeration Area

As coal resources are extracted in large quantities,a large amount of solid waste based on coal is produced.Due to the large amount of coal-based solid waste and difficult to deal with,a lot of coal-based solid waste exists in the form of stacking.Coal-based solid waste contains a large number of toxic and harmful substances,which is one of the main sources of pollution diffusion in the storage site.Long-term accumulation causes water,soil and air pollution,which seriously threatens the environment around the storage site and the safety of production and life of residents.Rainfall is one of the main driving forces and rainwater runoff is one of the main causes of pollution diffusion in storage yard.The spatial information model can effectively assess the environmental risks of rainfall-runoff and provide a basis for the pollution risk control of coal-based solid waste storage yards.In this thesis,the typical coal-based solid waste storage yards in Xishan Mining area is taken as the research object.In order to clarify the rainfall-runoff law of the storage yard,the rainfall-runoff law of small watershed of the storage yard is studied based on UAV oblique photogrammetry technology,watershed hydrology,geographic information science and other theories.The main work and achievements of this thesis are as follows:（1）By collecting data of Xishan mining area and combining remote sensing satellite image data,the general situation of Xishan mining area is investigated and analyzed.The coal-related industries in Xishan mining area are relatively concentrated in the bottom of the Fen River main stream in the valley and Sichuan,with large gathering area,small scale and high density,showing the characteristics of small-scale and high-intensity agglomeration,among which the northwestern Gujiao coal-related industry has the highest degree of agglomeration.The three coal-based solid waste storage yards in Gujiao mining area with high intensity mining are located near the water system,and the downstream water system has the risk of accepting the polluted water from the upstream storage yard.（2）The hydrological model of the Gujiao section of Fenhe River watershed was constructed based on the SWAT model.The measured hydrological data of Zhaishang Station were used for calibration and verification of the model.The periodic R² of the model rate was 0.79,the E_NS was 0.66,the R² of the model verification period was 0.74,and the E_NS was 0.59,indicating that the simulation data could better conform to the variation trend of the measured flow value,and the SWAT model had good applicability in this watershed.Based on the output results of the model,the thesis studies the influence characteristics of the three small drainage watersheds of Gujiao storage yard on the adjacent drainage systems.The results show that the area of small drainage watersheds of storage yards is not the determinant factor of the drainage yield,but is closely related to the properties of the underlying surface of storage yards and rainfall.From June to August,the rainfall yield of small drainage watersheds of storage yards is the largest,and the runoff flowing through storage yards into the adjacent drainage systems is also the largest.Are the months to focus on.（3）Based on the UAV oblique photogrammetry technology,DJI Jingwei M300RTK UAV equipped with SHARE 202S 5 lens camera was used to acquire high-precision image data of coal gangue storage yard.The images acquired were of uniform tone,moderate contrast,uniform image and no obvious shadow.Through image preprocessing and data processing of aerial triangulation,yard positive projective image data（DOM）,yard digital elevation model（DEM）and yard true three-dimensional model are produced,and the relevant accuracy indexes are verified to meet the research requirements.（4）Based on the obtained high-precision underlying surface data of the storage yard,GIS hydrological analysis technology was used to analyze the small drainage watershed of the storage yard,accurate the range of small drainage watershed and surface runoff distribution,and clear the main migration path of polluted rainfall-runoff in the small drainage watershed of the storage yard;Based on the analysis of small drainage watershed of the storage yard,a rainfall-runoff model of small drainage watershed was constructed based on the SWAT model using the high-precision underlying surface data of the storage yard,and the model was calibrated using the discharge results at the outlet of the small drainage watershed.The periodic R² and E_NSwere 0.94 and 0.92.In the verification period,R² is 0.81 and E_NS is 0.77,indicating that the simulation results of the model can better reflect the rainfall-runoff in the small watershed of the storage yard.The rainfall-runoff model established for small watersheds of the storage yard was used to simulate the rainfall-runoff situation of small watersheds of the storage yard from 2008 to 2018,and the rainfall-runoff law of small watersheds of the storage yard was analyzed according to the output results of the model.The results show that most of the water flow from the coal-based solid waste accumulation area will flow into the downstream drainage system,and the downstream drainage system has a higher potential risk of water pollution from the storage yard.The runoff produced by rainfall in the storage yard was the highest in July,followed by August and September,and the risk of water pollution from the storage yard was the highest in the downstream water system in summer.The properties of the underlying surface of the storage yard have an important impact on the rainfall-runoff.Improving the cover of the storage yard,interception,diversion and increasing the runoff from other areas are helpful to reduce the risk of pollution of the downstream water system.The rainfall-runoff simulation model and method proposed in this thesis based on UAV tilt photogrammetry technology and SWAT model can reasonably simulate the situation of surface water flow generated by rainfall in storage yard,and is suitable for the study of rainfall-runoff law in small watersheds of storage yard.Relevant theories and methods have important application value for rainfall-runoff prediction and management in small watersheds of storage yard.