A stochastic framework for rainfall intensity–time scale–return period relationships. Part I: theory and estimation strategies

ABSTRACT

This work presents a stochastic framework for the construction of rainfall intensity–time scale–return period relationships, which was applied in the recent regionalization of design rainfall curves over the Greek territory, described in a companion paper. The methodology outlined herein builds upon a widely-used mathematical framework, which has been recently revisited and upgraded, and incorporates two different versions: (a) a theoretically consistent stochastic model applicable for rainfall intensity over any scale of interest; and (b) a simplified version valid over small scales, which makes parameter estimation easier. Special attention is given to the presentation of the simplified version, which suffices for most engineering tasks. Parameter estimation approaches are presented in detail, including the K-moments framework that allows for reliable high-order moment estimation and handling of bias due to spatiotemporal dependence.

KEYWORDS:

• Rainfall modelling
• extreme rainfall
• design rainfall
• intensity–duration–frequency curves
• tail-index
• K-moments
• stochastic modelling

Editor A. Castellarin; Associate Editor E. Volpi

Editor A. Castellarin; Associate Editor E. Volpi

Acknowledgements

We are grateful to the Associate Editor Elena Volpi and two anonymous reviewers for their comments which helped us to improve the manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The PythOm package may be used to apply the all-scale version of the ombrian model (Iliopoulou and Koutsoyiannis 2021).

Additional information

Funding

This research was funded by the General Directorate of Water of the Greek Ministry of Environment and Energy through the unit “Eπιτελική ∆oμή EΣΠA Υπoυργείoυ Περιβάλλoντoς και Eνέργειας Toμέα Περιβάλλoντoς” in the framework of the project “Production of maps with updated parameters of the ombrian curves at country level (implementation of the EU Directive 2007/60/EC in Greece).”