| The core content of the distributed hydrological model to study the spatial distribution of hydrological variables is spatial discretization.It is an important basis for hydrological models to improve simulation efficiency and be widely used to establish appropriate hydrological models to establish hydrological models.Research on spatial discretization based on DEM has been initially explored in hydrological models.This study is based on the micro-terrain digital elevation model(M-DEM).The grid size is used to divide the M-DEM grid size into 1mm-10mm,and the impact of spatial discretization on the hydrological characteristics of the basin is analyzed.Based on the basic principles of multiple disciplines,GIS technology,and cellular automaton model method,combined with distributed hydrological model to build SCS-CA model and CA confluence model,for different rain intensity(1mm/min,1.5mm/min),artificial digging and cultivating the slope confluence on the micro-topography of loess under different slopes(5°,10°,15°).Through statistical analysis of model confluence simulation results and measured data,the effect of spatial discretization on hydrological model confluence simulation effects is studied and the best discrete grid unit for model operation is determined.The main conclusions of this paper are as follows:(1)The degree of DEM grid discretization has an important influence on the extraction of hydrological features based on DEM.Among them,the numerical effects on the length of the flow path,the length of the main channel and the slope are greater,and the elevation is less affected by the grid dispersion.At the same time,the water collection threshold that determines the structure of the virtual river network also changes.(2)Through the statistical analysis of the simulation results and measured data of the SCS-CA model and CA confluence model,it can be seen that the spatial discretization has an important influence on the simulation results of the hydrological model.The best discrete grid cell size of SCS-CA model for 5°slope,10°slope and 15°slope at 1mm/min rain intensity is 4mm,5mm and 4mm,respectively;The optimal discrete grid cell size of the CA confluence model at a slope of 5°at a rain intensity of 1.5 mm/min is 4 mm;At 1mm/min rain intensity,the optimal discrete grid cell sizes for the 5°,10°and 15°slope CA confluence models are 5mm,6mm and 6mm,respectively;The optimal grid cell size of the CA confluence model at a slope of 1.5°at a rain intensity of 5 mm/min is 6 mm.(3)Through the analysis of the simulation results of the grid model with different degrees of dispersion(1mm-10mm),it can be seen that under the same rainfall conditions,with the increase of the grid,the simulated flow of the model decreases.And when building a hydrological model,it is not that the smaller the grid,the better the simulation results of the model.The simulation results are better within a certain grid size,and the simulation errors of the hydrological model beyond this grid range are very large.Therefore,in the application of the model,researchers need to select the best discrete grid unit or find the range of the discrete grid with better model simulation results according to the specific watershed and the simulation accuracy of different models.(4)According to the r~2 measure of the relative gain of the simulation results of the SCS-CA model and the CA confluence model,the simulation effect of the SCS-CA model is better than that of the CA confluence model on the loess micro-terrain slopes and manual digging and cultivation measures.In summary,based on GIS technology,cellular automaton model theory and method,this study builds a distributed SCS-CA model and CA confluence model to simulate confluence based on M-DEM,and successfully achieves the spatial dispersion of micro-terrain It provides a new research idea for determining the best discrete grid unit of the hydrological model based on the grid method,and is of great significance to the spatial discretization research of the hydrological model. |
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