Climate change impact and uncertainty analysis of extreme rainfall events in the Apalachicola River basin, Florida

Climate change impact on rainfall intensity–duration–frequency (IDF) curves at the Apalachicola River basin (Florida Panhandle coast) is assessed using an ensemble of regional climate models (RCMs) obtained from the North American Regional Climate Change Assessment Program. The suitability of seven RCMs on simulating temporal variation of rainfall at the fine-scale is assessed for the case study region. Two RCMs, HRM3–HADCM3 and RCM3–GFDL, are found to have good skill scores in generating high intensity events at the mid-afternoon (2:00–4:00 PM). These two RCMs are selected for assessing potential climate change impact on IDF curves. Two methods are used to conduct bias correction on future rainfall IDF curves, i.e., maximum intensity percentile-based method, and sequential bias correction and maximum intensity percentile-based method. Based on the projection by HRM3–HADCM3, there is no significant change in rainfall intensity at the upstream and middle stream stations but higher intensity at the downstream station. RCM3–GFDL projected increased rainfall intensity from upstream to downstream, particularly at the downstream. The potential temporal shift of extreme rainfall events coupled with overall increased intensities may exacerbate flood magnitudes and lead to increased sediment and nutrient loadings to the estuary, especially in light of sea level change.