Numerical investigation structural protection measures for riverbank due to flood flow-driven damage.

A three-dimensional Computational Fluid Dynamics (CFD) model was employed to investigate the impact of structural protection measures on riverbanks subjected to flood flow-driven damage. Three structural approaches are applied to a case study the downstream river of Cua Dat spillway: (i) three groups of submerged groynes with varying height ratios R = 1.04, 2.13 and 3.14 of flow depth (do) to groyne height (hg), (ii) detention zones and (iii) concrete lining. Several hydraulic characteristics at near-bank flow, such as Qvortex, near-bank velocity (Vbank) and impact load (F) acting on bank protection slabs. Groups of submerged groynes redirect high-velocity flow toward the mainstream, which may jeopardize the integrity of bridge piers. The lower-submergence scenario (R = 1.04) generates maximum impact forces on the upper slab layer approximately 3.5 times greater than those induced by no protection measure. Results indicate that excavating natural detention zones along the left riverbank, in combination with concrete lining on the right riverbank, effectively reduces flood risk not only at structurally vulnerable zones but also at the bridge. These findings provide practical insights into the hydraulic performance of structural measures for riverbank stabilization in high-risk spillway environments.