Short duration extreme precipitation intensity/duration

Sector Infrastructure
Description Statistical characterization of extreme short-duration precipitation
End User water services, city planners and consultants dealing with design and management of infrastructure sensitive to pluvial flooding.
Calculation method ID Title Period Statistical processing Unit Threshold Comment
intdurfreq IntensityDurationFrequency (IDF) curve Selected accumulation periods (AP) from 15 min to 24 h Precipitation time-series of length 5 years and resolution 15 min from nine locations inside the domain are joined to form a 45-year time series. For each AP, annual maxima are extracted and a GEV (Generalized Extreme Value) distribution is fitted to these 45 values. From the fitted GEV distributions, the intdurfeq indicator is produced by the estimated intensities for return periods 5, 10, 50 and 100 years. See further Urban SIS deliverable 5.3 (section mm AP-1  


arearedfac Areal Reduction Factors (ARFs) Selected accumulation periods (AP) from 15 min to 24 h The above procedure (intdurfreq) is performed for time series of spatial averages (SA) surrounding each of the nine locations, from SA = 9 km² (3×3 grid cells) up to 121 km² (11×11 grid cells). The arearedfac indicator is produced by dividing the estimated intensities values for different SA-values with the corresponding intdurfreq value (i.e. for the same AP and return period). See further Urban SIS deliverable 5.3 (section    
Provenance Theese indicators are based on output from the Harmonie meteorological modell.
Validation The simulations made by HARMONIE-AROME in Urban SIS has been validated against observations in Urban SIS deliverable 5.1, where an overview is given in Table 4. For precipitation a more extensive analysis have been made in section 4.2. For intense precipitation a more extensive validation is done in Urban SIS deliverable 5.3, where in particular section 4.1.2 gives a more in depth validation for precipitation patterns and intensity.
Calculation caveats Spatial representation: S4
Other caveats: 
Could be compared to: C5, C6
Could be used with: U4 (flood models)

These indices represent the type of information on short-duration rainfall extremes used in urban hydrological analysis and design.

Experience user  
References Maidment DR (Ed.) 1993: Handbook of hydrology. New York, McGraw-Hill.