[A-HW22] River Channel Morphology, Water Resource Management, and Advanced Techniques

[AHW22-P01] Assessing Levee Overtopping Risks Under Climate Change: A Numerical Investigation of Water Level Variations in the Tamsui River Basin

*Cheng-Chia Huang¹, Hsiang-Yun Hsu¹, Chiao-Yin Hsu¹ (1.Feng Chia University)

Keywords:Climate Change, HEC-RAS, Levee Safety, flood risk, adaptation strategies

Levees serve as critical flood protection structures, yet their effectiveness under climate change scenarios remains uncertain. This study adopts the Taiwan capital river basin, Tamsui River, to be the simulation area and employs numerical modeling, HEC-RAS, to evaluate levee safety in the Tamsui River Basin by analyzing water level variations under historical extreme floods and climate change scenarios. This study simulates long-term flood events (2004-2024) to assess potential risks posed by increased flood magnitudes. The primary focus is on whether changes in peak water levels under historical typhoon-induced floods and future climate-driven precipitation increases could increase the likelihood of overtopping. The methodology includes reconstructing past bed elevation and extreme floods and simulating future flood scenarios based on projected rainfall intensity increments due to climate change. By analyzing the water level along the river, this study assesses critical flood thresholds that could challenge the current levee level design. The results indicate that extreme precipitation events significantly elevate water levels, increasing the probability of levee overtopping in vulnerable sections. In particular, future flood scenarios with higher rainfall intensities demonstrate a notable rise in peak flood levels, posing greater challenges for flood control infrastructure. Furthermore, comparing historical and future flood events highlights a progressive increase in flood risk, emphasizing the need for adaptation strategies. The study suggests that levee height and emergency response measures should be reassessed to ensure resilience against intensifying flood events. Given the uncertainty associated with climate projections, a risk-based approach integrating numerical modeling with real-time monitoring is recommended for future flood management. This study provides critical insights for policymakers, engineers, and floodplain managers in designing more adaptive flood mitigation strategies. The findings reinforce the necessity of continuous levee assessment to accommodate evolving hydrological conditions. In conclusion, future research should focus on refining climate projections, incorporating real-time hydrological data, and evaluating additional flood adaptation measures to enhance the reliability of flood protection infrastructure.