Enhancing Infrastructure Resilience in Alabama through Climate-Informed IDF Curve Development

Rainfall Intensity-Duration-Frequency (IDF) curves are essential for designing infrastructure to manage runoff, including stormwater systems, drainage networks, and flood control structures. Traditionally, these curves are derived from statistical analyses of historical rainfall data, based on the assumption of stationarity, which presumes that past precipitation trends will continue unchanged. However, the growing impact of climate change has increasingly invalidated this assumption, underscoring the need for IDF curves that incorporate non-stationarity to more accurately predict future precipitation patterns. This study addresses this challenge by utilizing the Generalized Extreme Value (GEV) distribution and the Generalized Maximum Likelihood Estimation (GMLE) method to develop updated IDF curves for Alabama, USA. The novel aspect of this work lies in the integration of high-resolution climate projections under various Shared Socioeconomic Pathways (SSPs) scenarios, using downscaled CMIP6 daily precipitation data from the Geophysical Fluid Dynamics Laboratory’s Earth System Model (GFDL-ESM4). The LOCA downscaling technique enhances the spatial resolution of climate model data, making it more relevant for local-scale infrastructure planning. The study estimates 24-hour precipitation depths for different return periods (2, 10, 50, 100, 200, and 500 years) across Alabama, based on both historical and future climate data. Model reliability is validated by comparing historical simulations with current NOAA Atlas 14 estimates. Future projections indicate a significant rise in the frequency and intensity of extreme precipitation events, with the SSP3-7.0 scenario showing the most substantial increases. These results suggest that Alabama could face more intense and frequent rainfall in the coming decades, presenting significant challenges for infrastructure designed on historical data. To mitigate these challenges, it is crucial to update design standards for stormwater management and other infrastructure to incorporate future climate projections. This approach involves adopting adaptive management strategies, enhancing monitoring and data collection systems, and integrating climate projections into policy frameworks. By implementing these measures, Alabama can strengthen the resilience of its infrastructure to future climatic conditions, safeguarding property and public safety. This study offers a comprehensive methodology for developing IDF curves that consider future climate scenarios, providing valuable insights for infrastructure planning and climate adaptation strategies.