Study on the River Network Extraction Method from Complex Surface Based on Trend Surface Fitting

If the degree of polynomial is properly determined, the trend surface can be fitted in complex terrain. The trend surface can be fine-tuned by filling the depression. Based on the free flow model, the flow direction is determined. The least square method is used to determine the length of water flow. Finally, the confluence analysis is carried out to generate the river network. The experimental results show that the river network extracted from the complex surface is in good agreement with the actual river network based on the trend surface fitting.