Two-Step Simulation of Underwater Terrain in River Channel

Abstract

When studying river hydrodynamics and water quality evolution laws on the basis of numerical simulation analysis, it is necessary to carry out topographic interpolation along the bend direction of the river on the basis of the measured river section, as this can provide accurate and reliable topographic data for river numerical modeling. In this paper, a two-step terrain simulation method based on sparse and discrete river sections is proposed by comprehensively considering the river trends and the lack of monitoring sections. On the basis of establishing a reference using the river centerline and coding the spatial relationship of the river, the linear weight method, which uses the distance and gradient change between the known sampling elevation section to realize the preliminary encryption of spatial points with any number of longitudinal sections and any horizontal distance, is carried out first. Considering the structural and anisotropic characteristics of the river, the improved inverse distance weighting (IDW) method is further used to locally interpolate the encrypted points to obtain the continuous surface of the river terrain. In order to prove the effectiveness of this method, a part of the Qinhuai River in Nanjing was taken as the research object. The experiment was carried out by setting different spacing distances for preliminary densification and by using different interpolation methods for further local terrain simulation. Root mean square error (RMSE) and mean absolute error (MAE) are used to evaluate the overall performance of different simulation methods. The experimental results show that the method proposed in this paper overcomes the obvious inaccuracy of directly using an interpolation algorithm to generate the river terrain due to sparse section data. The river terrain generated by the preliminary densification and improved IDW interpolation calculation method is more reasonable, and continuous and unobstructed, reflecting the original river terrain more accurately.