The Texas Triangle, one of the fastest-growing regions in the United States, is also highly vulnerable to extreme rainfall and flooding. As cities such as Dallas, Fort Worth, Austin, San Antonio, and Houston continue to expand, it becomes important to understand how urban growth could influence future storms. In this study, we used a detailed weather model (WRF-Chem) to simulate the effects of projected urban expansion on rainfall and flood risk during two real storms: a winter frontal system in February 2017 and a prolonged summer rainstorm in August 2022.

Urban growth increases emissions of small particles that help form cloud droplets. In February, all four cities experienced a clear increase in rainfall, driven by stronger cloud updrafts and more heat released from condensation. In August, with a warmer and more humid atmosphere, the rainfall response was more complex. Rainfall decreased in newly urbanized areas of Dallas, while Fort Worth showed localized increases within the original urban core.

We also produced high-resolution flood risk maps, showing that future urban development may create new areas vulnerable to flooding, while preserving existing high-risk zones. These results show how land-use changes and urban pollution can reshape how storms affect this already flood-prone region.