IDFcurves
IDF curves, or intensity–duration–frequency curves, are a foundational tool in hydrology and civil engineering used to estimate the characteristics of rainfall events for design and risk assessment. For a given location, an IDF curve expresses the expected rainfall intensity (mm/h) as a function of storm duration (minutes to hours) for a specified return period (e.g., 2-year, 10-year, 100-year). They underpin the selection of design storms for sizing drainage networks, culverts, and detention facilities, and are also used in rainfall–runoff modeling and flood risk assessments.
IDF curves are constructed from long-term rainfall records, typically by analyzing annual maximum rainfall for different
To use, engineers choose location and return period, pick the duration of interest, and read the corresponding
Limitations include uncertainties from record length, measurement errors, non-stationarity due to climate change, and extrapolation beyond