Evaluating Flood Adaptation Effectiveness through Economic Analysis: A Case Study of Surat, India

Floods are among the most costly natural disasters globally and are projected to increase in frequency and magnitude with a warming climate. To confront increasing flood risks, flood managers need the most cost-effective adaptation actions to reduce economic damage to floodplain infrastructures. Recent research advancements have explored the physical aspects of flood adaptation strategies such as levees, diversions, and barrages. However, implementing adaptation actions requires comprehensive economic analysis before execution due to the substantial capital investment involved. Here, we develop a 1D-2D coupled hydrodynamic flood model in the MIKE+ platform, considering river flow to generate flood inundation maps for various hydraulic inland scenarios. We generate inundation maps for 10-, 50-, 100-, and 200-year return periods of design discharge, considering flood adaptation strategies. Subsequently, we utilize available flood depth-damage functions to calculate expected flood damage and conduct a cost-benefit analysis of the proposed adaptation strategies. We demonstrated the proposed framework for the coastal city of Surat, India. Our results provide the decision matrix to select adaptation strategies based on design standard objectives. The initial assessment highlights that a combination of levee and barrage is more effective than individual levee, barrage, and diversion strategies, particularly in terms of cost-effectiveness in reducing flood damage. Our framework would be beneficial in selecting effective planning strategies for reducing flood damage.