Effects of Land Use Change on Surface Runoff and Infiltration: The Case of Dhaka City

This study presents an integrated field- and model-based assessment of how rapid urbanization is transforming water infiltration and storm runoff dynamics in Dhaka—a megacity facing escalating flood risks. Unlike conventional studies that rely solely on secondary or modeled datasets, this research combines extensive in situ field measurements of soil infiltration with scenario-based hydrological modeling to capture the localized impacts of land use change. Using the SCS Curve Number and Water Balance methods, the study quantifies how variations in land cover under different urban growth trajectories alter surface runoff behavior. Results show that Dhaka’s annual infiltration rates—measured at 2034 mm, 1546 mm, and 1074 mm during wet (2017), normal (2018), and dry (2020) years—could decline by nearly 50% if current urban expansion trends persist. Concurrently, surface runoff volumes are projected to nearly double, amplifying flood hazard potential across the city. By grounding scenario modeling in empirical local data, this work offers a context-specific understanding of the evolving hydrological regime of a rapidly urbanizing South Asian metropolis, providing a framework for flood resilience planning in other data-limited cities.