Uncertainty Quantification in Rainfall Intensity Duration Frequency Curves Based on Historical Extreme Precipitation Quantiles

Intensity Duration Frequency (IDF) curves form the basis for quantifying the magnitude of rainfall events those are used in the design of a variety of civil infrastructure, especially in an urban environment. It is important that the capacity of urban infrastructure (e.g. storm sewers, culverts, and storm water management ponds) be appropriately sized to avoid overdesigned or underdesigned, which could lead to economic losses, increased property damage and possible increased risk of loss of life. Thus, obtaining high quality estimates of IDF curves is important. Uncertainty in IDF curves is usually disregarded in the view of difficulties associated in assigning a value to it. Latin Hypercube Sampling (LHS) and regional frequency analysis based on L-moments approach were utilized in order to estimate the uncertainty in the IDF curves based on historical extreme precipitation quantiles from different stations in the Langat River Basin. Uncertainties of the rainfall intensity in IDF curves were estimated with the bootstrap sampling method, and were described by a GEV distribution. Shape parameter, scale parameter, and location parameter, were modeled as the functions of rainfall duration and rainfall intensity using 103 LHS set samples for all the durations and return periods considered for each rainfall station.