As a result of global warming, the occurrences of floods have increased in frequency and severity. Flooding often occurs near rivers and low-lying areas, which makes such areas higher-risk locations. Flood-risk evaluation represents an essential analytic step in preventing floods and reducing losses. However, the uncertainty and nonlinear relation between evaluation indices and risk levels are always difficult points in the evaluation process. Fuzzy comprehensive evaluation (FCE), an effective method for solving random, fuzzy and multi-index problems, has led to progress in understanding this relation. Thus, in this study, an assessment model based on FCE is adopted to evaluate flood risk in the Dongjiang River Basin. To correct the one-sidedness of the single weighting method, a combination weight integrating subjective weight and objective weight is adopted based on game theory. The evaluation results show that high-risk areas are mainly located in regions that include unfavorable terrain, developed industries and dense population. These high-risk areas appropriately coincide with the integrated risk zoning map and inundation areas of historical floods, proving that the evaluation model is feasible and rational. The results also can be used as references for the prevention and reduction of floods and other applications in the Dongjiang River Basin.

A comprehensive comparison between the Hertz–Mindlin model and the linear spring model in true triaxial shear simulations of granular soils was conducted using the discrete-element method (DEM). The no-slip Hertz–Mindlin model for general elastic non-spherical particles with smooth surfaces was revisited and implemented for superellipsoidal particles in an in-house DEM code. Three groups of specimens with a grain size distribution of Ottawa 20–30 sands, consisting of spheres, ellipsoids and superellipsoids, respectively, were subjected to triaxial shear DEM simulations with the Hertz–Mindlin model and the linear spring model. The corresponding mechanical behaviours were examined in terms of a series of macro- and micro-parameters. It was found that the linear spring model was able to resemble the Hertz–Mindlin model in aspects of both microscopic and macroscopic mechanical behaviours of granular media with spherical and/or non-spherical particles. This finding suggests that the linear spring model can be used to investigate micro-mechanical behaviours of granular soils, even with complex particle shapes.