Estimation of Peak Discharges under Different Rainfall Depth–Duration–Frequency Formulations

Andrea Gioia,Tiziana Bisantino,Matteo Gianluca Molfetta,Vincenzo Totaro,Ciro Apollonio,Beatrice Lioi,Vito Iacobellis

doi:10.3390/hydrology8040150

Andrea Gioia, Tiziana Bisantino + Show 5 more

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https://doi.org/10.3390/hydrology8040150

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Abstract

One of the main signatures of short duration storms is given by Depth–Duration–Frequency (DDF) curves. In order to provide reliable estimates for small river basins or urban catchments, generally characterized by short concentration times, in this study the performances of different DDF curves proposed in literature are described and compared, in order to provide insights on the selection of the best approach in design practice, with particular reference to short durations. With this aim, 28 monitoring stations with time series of annual maximum rainfall depth characterized by sample size greater than 20 were selected in the Northern part of the Puglia region (South-Eastern Italy). In order to test the effect of the investigated DDF curves in reproducing the design peak discharge corresponding to an observed expected rainfall event, the Soil Conservation (SCS) curve number (CN) approach is exploited, generating peak discharges according to different selected combinations of the main parameters that control the critical rainfall duration. Results confirm the good reliability of the DDF curves with three parameters to adapt on short events both in terms of rainfall depth and in terms of peak discharge and, in particular, for durations up to 30 min, the three-parameter DDF curves always perform better than the two-parameter DDF.

Highlights

The investigations about the increasing of extreme events at a global level carried out in last decades generated a debate on the need of revisiting the risk management approach, in particular with regard to rainstorms and floods
In small river basins, characterized by short concentration times, the traditional approach based on the use of two-parameter Depth–Duration–Frequency curves for the evaluation of the rainfall design fails for durations close to zero, as the rainfall intensity diverges and tends to have unreliably high values
A number of rainfall monitoring stations, with time series characterized by sample size greater than 20, were selected in the study area located in the Northern part of the Puglia region (South-Eastern Italy)

Summary

Introduction

The investigations about the increasing of extreme events at a global level carried out in last decades generated a debate on the need of revisiting the risk management approach, in particular with regard to rainstorms and floods. Concerns and possible consequences deriving from changes in an extreme rainfall regime led scientists and practitioners to investigate the influence of these events on the current design practice. One of the most used tools in water management are the Depth–Duration–Frequency (DDF) and Intensity– Duration–Frequency (IDF) curves, which have the valuable quality of being analytical relationships able to provide a design rainfall depth (or intensity) for an assigned duration and return period [1,2]. Concerns about past changes and possible evolutions of climate on the phenomenology of rainfall raised questioning about the opportunity of retaining the still valid adoption of stationary hypothesis during the IDF/DDF deriving procedure [7,8,9,10]. Implications arising from the adoption of nonstationary probability distributions for modelling changes in extremes and applications of related statistical tests for trend detection were discussed in several studies (e.g., [11,12,13,14,15,16,17,18])

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