Digitized Penang JICA Drainage Study Floodmap

The state of Penang, Malaysia is currently suffering from widespread flooding (5th November, 2017). The current flood comes on the heels of an earlier flood just one and a half months ago in mid September.

As part of the design and maintenance of a sensible urban planning policy, a proper understanding of the area's flood risks is required. Comprehensive flood studies are used to quantitatively analyze and evaluate the risks, hazards and potential human & economic losses associated with potential flood events.

Often, flood studies are lacking in developing parts of the world due to data, expertise and resource constraints. The current tragic flood event has prompted me to search for any data that may help inform the general public of the city's flood risk.

Flood Risk Data

I had managed to dig out an old 1991 drainage and flooding study of Penang produced by JICA. This study had produced a flood map for 5, 10, 30, 50 & 100 year ARI events. Unfortunately, the poorly scanned map is not very accessible for the general public due to missing roads and features from the scanning process as well as unnecessary clutter from the map's design:

Georeferencing & Data Transformation

In order to improve the accessibility of this floodmap and assist with informing the general public. I had georeferenced the scanned image in GIS and digitized the 5, 10, 50 and 100 year ARI flood extent boundaries.

Digitized Data on Online Map UI

The digitized data presented in a modern map UI below should help inform the public about the flood risks in Penang.

Words of Warning

The JICA study is published in 1991 and is considered very dated especially with regards to input such as landuse patterns, drainage infrastructure, and terrain due to the tremendous amount of growth in Penang Island.

As with all flood studies, there are not-insignificant amount of uncertainty associated with the results. It is therefore prudent to treat any flood map only as a rough guide.

Finally, I am not the author of the JICA paper. My effort only included the digitization of the flood map results and making it accessible via the internet. Please read the original report to gain an understanding of the modeling process and parameters.

Finally, there are no guarantee on the quality and suitability of the digitized map itself. Use at your own risk.