Maximum Precipitable Water for Estimating PMF
Hill et al. (2025) describe an approach for deriving preliminary estimates of the Probable Maximum Flood in m³/s based upon the maximum precipitable water (PW) in mm (or kg/m²) and the catchment area (A) in km².
The estimate of the maximum precipitable water was extracted from the ERA5 global meteorological reanalysis data set developed by the European Centre for Medium-Range Weather Forecasts (ECMWF) (Hersbach et al., 2020). The daily mean values were calculated from the hourly data for the period between 1950 and 2022 and then the maximum daily value extracted.
Hill et al (2025) provides a global map of the resulting maximum precipitable water. The following more detailed results are provided to assist application to a specific catchment:
- Gridded (0.25° x 0.25°) data set (3.96 Mb)
- Interactive map
Please refer to the paper for a description of the approach and associated limitations.
Download gridded dataReferences:
Hersbach, H., Bell, B., Berrisford, P., Hirahara, S., Horányi, A., Muñoz‐Sabater; J., Nicolas, J., Peubey, C., Radu, R. and Schepers, D. (2020) The ERA5 global reanalysis, Quarterly Journal of the Royal Meteorological Society, 146(730), 1999–2049, 2020.
Hill, P.I., Rasheed, A., Shen, Y., Jordan, P.W. and M. Raymond (2025) Regionalisation of flood envelope curves to derive preliminary estimates of Probable Maximum Floods. Proceedings of 28th ICOLD Congress and 93rd Annual Meeting. Chengdu, China 16th-23rd May 2025.
