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Impacts on Floods
Extreme Rainfall and Rainfall-Intensity-Duration-Frequency Curve
Prof. Srikantha Herath Academic Director, United Nations University, Institute for Sustainability and Peace
Visiting Professor, Integrated Research Systems for Sustainability Science, University of Tokyo
This session aims to: (1) introduce the nature of these extreme events under climate change; (2) introduce rainfall-intensity-duration-frequency (RIDF) curves and how to convert them to account for future climate change; and (3) application of the RIDF curves for design floods of small rural and urban watersheds.
The nature and characteristics of extreme rainfall and runoff events are projected to change under climate change. To a certain extent, changes in the characteristics of these extreme events have already been observed and also GCM simulations of future climate change projections indicate the changes in characteristics of these extreme events. However, the observed data are too short to project changes in these extreme events especially with the non-stationarity and evolutionary nature of climate change and also it is recognized that there are limitations and constraints of GCM simulations in handling extreme events. Thus, this is challenge to hydrology in dealing with extreme events under climate change. The rainfall-intensity-duration-frequency (RIDF) curve is used in hydrology to estimate design floods. The derivation and application of RIDF curves with observed data (historical past) and with GCM simulations data (under climate change) are illustrated in this session.
1. Spatial and Temporal Characteristics of Extreme Event
2. Limitations and Constraints of GCM/RCM in Handling Extreme Events
3. Derivation of Extreme Event Statistics from GCM Data
4. Uses of Rainfall Intensity-Duration-Frequency (RIDF) Curves
5. Derivation of RIDF Curves
6. Converting RIDF Curves with Climate Change
7. Present versus Future RIDF Curves
8. Applications of RIDF for Design Floods of Small Rural and Urban Watershed
The students are expected to learn about the nature and characteristics of extreme rainfall and runoff events especially under climate change and to learn about the use and application of the rainfall-intensity-duration-frequency curves for design floods under Climate change.
Mishra, B.K. and Herath, S. (2012): Investigating potential climate change impacts on rainfall intensity duration frequency curves in Kathmandu, Nepal, Proceedings of 11th International Symposium on New Technologies for Urban Safety of Mega Cities in Asia, October 10-12.