Addressing uncertainty in extreme rainfall intensity for semi-arid urban regions: case study of Delhi, India
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Addressing uncertainty in extreme rainfall intensity for semi‑arid urban regions: case study of Delhi, India Ranjana Ray Chaudhuri1 · Prateek Sharma2 Received: 4 January 2020 / Accepted: 27 August 2020 © Springer Nature B.V. 2020
Abstract Classical approaches are used to develop rainfall intensity duration frequency curves for the estimation of design rainfall intensities corresponding to various return periods. The study modelled extreme rainfall intensities at different durations and compared the classical Gumbel and generalized extreme value (GEV) distributions in semi-arid urban region. The model and parameter uncertainties are translated to uncertainties in design storm estimates. A broader insight emerges that rainfall extremes in 1 h and 3 h are sensitive to the choice of frequency analysis (GEV in this case) and helps address anticipated intensification of extreme events for short duration at urban local scale. In comparison with Gumbel, GEV predicts higher extreme rainfall intensity corresponding to various return periods and duration (for 1-h duration the increase in extreme rainfall intensity is from 27 to 33% for return periods 10 years and higher, 3-h and 50-year return period—20%, 3-h and 100-year return period—20.6%, 24 h at similar return periods—10%). The Bayesian posterior distribution has a calibration effect on the GEV predictions and reduces the upper range of uncertainty in the GEV probability model prediction from a range of 16–31% to 10–28.4% for return period varying from 10 to 50 year for 1-h storms. In geographically similar areas these extreme intensities may be used to prepare for the rising flash flood risks. Keywords Extreme rainfall · Short duration · Uncertainty · Semi-arid · Bayesian · Delhi
Electronic supplementary material The online version of this article (https://doi.org/10.1007/s1106 9-020-04273-5) contains supplementary material, which is available to authorized users. * Ranjana Ray Chaudhuri [email protected] Prateek Sharma [email protected] 1
Department of Regional Studies, TERI School of Advanced Studies, 10, Institutional Area, Vasant Kunj, New Delhi 110070, India
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Department of Energy and Environment, TERI School of Advanced Studies, 10, Institutional Area, Vasant Kunj, New Delhi 110070, India
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Natural Hazards
1 Introduction Increasingly, the occurrences of flash floods (Westra et al. 2014) with the rise in intense short-duration rainfalls is leading to a greater demand for understanding rainfall patterns through the local scale hydrologic variables like rainfall intensity of short-duration extreme events (Groisman et al. 2012; Prein et al. 2017). The rainfall intensity duration frequency (IDF) curves are used to design hydraulic structures to carry stormwaters through the city; an increase of 30% in design storm intensity is envisaged for Belgium due to climate change (Willems 2013), an increase of 10% in design estimates for Denmark (Madsen et al. 2009) and 34–48% increase in rainfall (1–24 h) in Vietn
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