Hydraulic and ecological comparison of Gabion and reinforced Earth revetments in Keelung river Taiwan.

Abstract

In response to climate change and increasing flood risks, Taiwan has adopted nature-based solutions to enhance riverbank resilience and ecosystem services. This study evaluates the hydraulic and ecological performance of gabion and reinforced earth revetments installed along the Keelung River after Typhoon Nari (2001). Using satellite imagery (1999-2020) and field surveys, we assessed vegetation recovery and plant diversity on both revetment types. Hydraulic modeling (HEC-RAS) simulated flow behavior under a 25-year flood and an extreme typhoon scenario to determine the impact of gabion and reinforced earth structures on flood mitigation. Findings indicate that both revetment types support significant vegetation regrowth, with reinforced earth revetments achieving ~ 13% higher coverage and greater species richness due to their sediment-retentive geotextiles and favorable surface conditions. Gabion revetments also promoted revegetation, particularly in high-flow zones. Hydraulic simulations revealed that both revetments installations reduced peak water depths and near-bank flow velocities, enhancing riverbank stability and decreasing erosion risk. These eco-engineering approaches improve flood safety and deliver long-term ecological and climate adaptation benefits, underscoring their value in sustainable river management.