HYDROLOGICAL EXTREMES

IN THE MEGACITIES OF TOKYO 

DATA PRODUCTION

Climate impact indicators
Global essential climate variables/indicators used

Maximum annual rainfall on hourly (or less) and daily time steps are needed to assess the design rainfall. Continuous rainfall time series are desirable.

Regional/local indicators used and produced

Rainfall Intensity-Duration-Frequency (IDF) curves are evaluated by C3S Global Service data and compared with local observations. The Tokyo Storm Runoff (TSR) model will be run to evaluate the impact of climate change in terms of the inundation depth variations in a small urban watershed.

Global data to regional/local scale

Step 1: Collect rainfall data from climate projections for Tokyo; one high-resolution (10 min / 5 km) RCM projection from JMA's Meteorological Research Institute (MRI) and several GCM projections from the Climate Data Store (and potentially also other data bases).

Step 2: Compare the RCM projection with the GCM ensemble (at the GCM resolutions).

Step 3: Calculate IDF curves and design rainfalls for present climate in the RCM projection.

Step 4: Compare the results from Step 3 with IDF curves and design rainfalls from historical observations in Tokyo.

Step 5: Calculate IDF curves and design rainfalls (local CIIs) for future climate in the RCM projection. Compare with pre-simulated flood risk scenarios obtained by the Tokyo Storm Runoff model for different design rainfalls. Express flood risk in terms of e.g. number of flooded manholes and/or inundated area (local CIIs).

Step 6: Visualize rainfall and flood risk changes in an interactive atlas.

  
Department of Civil and Environmental Engineering, Tokyo Metropolitan University (TMU)

 


Civil Engineering Support and Training CenterBureau of Construction of Tokyo Metropolitan Government

Poster displayed at the Kick–Off meeting, 7/8 September 2017, Norrköping, Sweden

Distribution of times for hourly rainfall of 50 mm