| The flash flood disaster is one of the most serious natural disasters in China.In the small watersheds where the mines are mined,slag accumulations may change the hydrological processes of the river basin,which may trigger more serious debris flow disasters at the mines.Flooding may flood the towns and cause flooding disasters.It is of great significance to study the formation of flash floods in slag drainage basins and flood inundation.This paper aims at the slag accumulation basin’s flood formation process and the flood inundation process.Through the construction of a two-dimensional numerical model of rainwater flooding and a numerical model of flood evolution,the impact of slag accumulation on the flood discharge capacity in the basin and the water depth distribution of the main channel in the basin are calculated and analyzed.At the same time,the submergence process and the distribution of inundated area when the floodwaters evolved in urban areas were studied.The accuracy,efficiency and stability of the model were analyzed.Mainly achieved the following research results:1.A set of basin terrain reconstruction methods is proposed,which can build a more reasonable basin terrain based on local high-precision terrain data and all low-precision terrain data,effectively improving the calculation accuracy of the flow process line.Through different interpolation methods and different interpolated width production and convergence analysis,it was found that the method of low sensitivity to interpolation width was TIN method,followed by Natural method and IDW method,and Kriging method had higher sensitivity of interpolation.At the same time,considering the high interpolation efficiency of the TIN method and good interpolation effect at the place where the elevation change is significant,the TIN method can be preferentially used in the terrain reconstruction,and the width of the transitional terrain is preferably selected to have the same natural slope ratio.2.A two-dimensional numerical model of the rain flood process in the Dasixi River Basin was established.The process of production and sinking of the landfill with or without slag topography was calculated under five kinds of return periods.The response rule of the torrential process to the slag landform was analyzed.The slag accumulation has a certain effect on the dewatering effect of the drainage section of the river basin;during the return period of five different types of rainfall,the effect of the peak reduction is most significant when the rainfall is 10 years old.When the return period of rainfall is less than 10 years,the terrain plays a major role in the size and arrival time of the flood peak.Influencing effects,on the contrary,the effect of the terrain gradually weakened;the peak reduction rate gradually increased as the section moved downstream.The research results have certain positive significance for reducing the flood risk downstream of the slag accumulation basin.3.A flood evolution model was established to obtain the submergence process and scope of urban floods when they were flooded for a hundred years,and the calculation accuracy,efficiency,and stability of the model and the existing models were quantified and compared.The GAST model simulated the percent error between the inundated area and the actual measurement results was only 0.96～4.36%.At the same time,the terrain time used for calculating the 5m and 2m resolutions was 2.17 h and 9.00 h,respectively,which had high simulation accuracy,efficiency,and calculation stability.Under the condition of input MIKE21 FM model,the calculation accuracy of GAST model is increased by 4.51～7.33 times;the calculation efficiency of GAST model is increased by 3.4～11.78 times,and the efficiency advantage is more obvious with the increase of the number of calculation grids,so its application prospect is broad. |
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