06 May 2008

Myanmar flooding from cyclone Nargis

Cyclone Nargis struck Myanmar (Burma) on 2 May 2008. Current NASA MODIS imagery and news reports indicate that this cyclone is an emerging humanitarian disaster.

From an informative Terra Daily news item:

At least 351 people were killed and nearly 100,000 left homeless when tropical cyclone Nargis tore through Myanmar, razing thousands of buildings and knocking out power lines, state media said Sunday.

The meteorological stats of the storm, as gleaned from the news item above...

Nargis made landfall late Friday around the mouth of the Ayeyawaddy (Irrawaddy) river, about 220 kilometres (137 miles) southwest of Yangon, before hitting the country's economic hub...

Electricity supplies and telecommunications in Yangon have been cut since late Friday night as the storm bore down from the Bay of Bengal, packing winds of 190-240 kilometres (120-150 miles) per hour.

These stats put it at the borderline Cat-3/Cat-4, suggesting a storm surge of ~4 m.

The image is a before-and-after comparison of the Ayeyawaddy province of Myanmar.Spatial dimensions of the images are 400x225 km. Yangon (nee Rangoon) is towards the upper right corner. The picture is a false-color image, comprised of visible and short-IR channels. Water appears black here; sediments in the water are dark blue (see here for description). The top panel is from 26 April; the bottom from 5 May, three days after the storm. Judging from the imagery, the area is largely low-lying river delta.

With the aid of this satellite image with the track superimposed, the storm presumably came ashore in the lower left of the image, near the large river. Comparison of the two images suggest the storm surge has been quite extensive. A swath of water is apparent across the peninsula (the storm track, perhaps?). Extended regions of the delta system are underwater –- new islands have formed off the new coastline, albeit temporarily.

The water over the former land is a deep blue hue, suggesting lots of erosion and silt transport out to sea.

Careful examination (and guesswork on the navigation!) indicate that the flood waters are very close to Yangon, as well. This is consistent with this statement (from the above news article): “There are also fears that the poorer outlying areas of Yangon, with their flimsy houses, might have been hard hit.”

An as-I-write post at The Intersection is indicating that up to 10 000 may be dead, and the normally reclusive government is appealing for international aid. These rare appeals, supported by the remote sensing data, would suggest that indeed they were hard hit.

Addendum: From Dr Jeff Masters' WunderBlog:

The storm hit the coast of Myanmar Friday night as borderline Category 3/Category 4 cyclone, with winds of 130-135 mph. After passing over the low-lying and densely populated Irrawaddy River delta region, Nargis made a direct hit on the capital city of Rangoon (Yangon), as a Category 1 storm with top winds of 80 mph...

However, it was the storm surge, not the winds, that was the big killer in Nargis. The storm tracked over the low-lying Irrawaddy River delta region, which is highly vulnerable to storm surge deaths due to its low elevation, dense population, and limited hurricane awareness of the people. I could find no records of a major tropical cyclone ever making a direct hit on the Irrawaddy River delta.
Again, as suggested by the imagery.

Addendum 2: Here is the official NASA Natural Hazards version of the picture above. They use a different 'before' picture, and their fancy image processing software and GIS make their image a bit crisper. Here is a MODIS true-color image of the cyclone at landfall.

Image: compiled by me, from raw material collected at NASA MODIS Rapid Response

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