The effect of depth‐duration‐frequency model recalibration on rainfall return period estimates

Abstract In November 2009 and December 2015, two record‐breaking 24‐hr rainfalls occurred in Cumbria, UK, significantly changing the perception of flood risk for local communities. FEH13, current UK rainfall depth‐duration‐frequency (DDF) model, estimated return periods around 1,000 years both events. The previous FEH99, received criticism from panel engineers responsible making technical safety decisions relating to reservoirs appearing estimate relatively short extreme Although FEH13 is more consistent with probable maximum precipitation (PMP) estimates, there high uncertainty models due limited number extremes captured by rain gauges. Furthermore, neither model included or 2015 event its calibration. Here, we re‐calibrate using additional gauged data collected Cumbria during 2006–2016, including storms. Using updated calibration set reduces events approximately 140 each. This case study illustrates considerable short‐sample records, demonstrates importance maximising quantity relevant data, shows that depends upon method used, difficulty separating trends natural variability.