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Impacts on Floods

Course Name: 
Climate Change Downscaling Approaches and Applications - Course 2 (2015)
Body: 

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

Objectives

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.

Description

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.

Outline

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

Learning Outcomes

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.

References

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.

Srikantha Herath

Academic Programme Director, Postgraduate Programmes; Head, Global Change, and Sustainability Section; and senior Academic Programme Officer, Institute for the Advanced Study of Sustainability, United Nations University, Tokyo, Japan.

Dr. Srikantha Herath engages in research and education in water security, climate change and natural disaster risk reduction. His postgraduate teaching and research currently focuses on global change impacts on environmental processes, especially related to atmospheric process with applications in urban hydrology, flood forecasting, damage estimation, sediment transport and water cycle change assessment using physically based distributed hydrological modelling aided by Remote Sensing and GIS.

Shigeru Nakamura

Deputy Manager, Research & Development Center, Nippon Koei Co., Ltd., Tsukuba, Japan

Mr. Shigeru Nakamura has been working on hydrologi- cal cycle analysis, watershed management, groundwater development and flood forecasting in Japan as well as in other Asian countries since 1989. He has been involved in research and development of a grid-based hydrological model and the SHER model. Currently, he is the in charge of the NK-GIAS development project in Nippon Koei co., ltd. He is also a board member of the Japan Society of Hydrology and Water Resources (JSHWR). 

Priyantha Bandara Hunukumbura

Researcher & Development Center, Nippon Koei Co., Ltd., Tsukuba, Japan

Dr. Priyantha Hunukumbura is currently working as a consulting engineer at Nippon Koei Co., Ltd. Japan. He specializes in hydrology and water resources engineering. His research interests focus mainly on monitoring and modeling of hydrological processes, studying the future effects of climate change on water resources in Asian countries, flood modeling and forecasting, prediction of ungauged basins, hydrological model transferability and GIS applications in hydrological modeling.