An Artificial Stream Network and Its Application on Exploring the Effect of DEM Resolution on Hydrological Parameters

Digital elevation models (DEM) are widely used in various distributed hydrological models. The stream network can be extracted from it so that runoff routing can be calculated. With the advent of remote sensing and computing technologies, the computation based on DEM with high resolution becomes possible. However, there still exist regions with poor resolution, particularly in developing countries. Previous work only conducted comparisons between results by implementing hydrological models for specific basins in the real world and resolutions were only assigned to several fixed values, such as 30 and 90 m. So, the results derived were thus not in a general sense. To roughly understand how DEM resolution influences the hydrologic response, in this paper, first an artificial stream network of which the principle is originated from fractal theory is constructed. Then by implementing calculation on such artificial networks in an iterative way and performing aggregation, the influence of DEM resolution on several hydrological parameters, namely, the number of basins, drainage density of all basins, total stream length, average stream slope and average topographic index used to assess the spatial distribution of soil saturation of the largest basin can thus be acquired. It is found that DEMs of low resolution would reduce drainage density, total stream length and average stream slope, but would increase topographic index. But the effect is insignificant regarding the number of basins. In the end, the results of the simulation as well as the quality of the fractal terrain are validated by referencing field data.