Mapping the Sulawesi Earthquake and Tsunami

The New York Times (detail)

Last week a magnitude-7.5 earthquake struck the Indonesian island of Sulawesi, triggering a tsunami that struck the city of Palu with far more force than expected. The New York Times has multiple maps and aerial images of the damaged areas; NASA Earth Observatory has before-and-after Landsat imagery.

The Changing Padma River

Padma River erosion animation
NASA Earth Observatory

Landsat observations have charted the erosion of the banks of the ever-changing Padma River, a major distributary of the Ganges in Bangladesh. This is vividly shown in this animation produced by NASA Earth Observatory, which “shows 14 false-color images of the Padma river between 1988 and 2018 taken by the Landsat 5 and 8 satellites. All of the images include a combination of shortwave infrared, near infrared, and visible light to highlight differences between land and water.” More on the erosion of the Padma River here.

Cape Town’s Disappearing Water Reservoirs

Cape Town is running out of drinking water, a crisis dramatically depicted by NASA Earth Observatory maps that show the depletion of the city’s reservoirs. The animated gif above, for example, “shows how dramatically Theewaterskloof [Cape Town’s largest reservoir] has been depleted between January 2014 and January 2018. The extent of the reservoir is shown with blue; non-water areas have been masked with gray in order to make it easier to distinguish how the reservoir has changed. Theewaterskloof was near full capacity in 2014. During the preceding year, the weather station at Cape Town airport tallied 682 millimeters (27 inches) of rain (515 mm is normal), making it one of the wettest years in decades. However, rains faltered in 2015, with just 325 mm falling. The next year, with 221 mm, was even worse. In 2017, the station recorded just 157 mm of rain.”

Google’s Cloud-Free Mosaic Gets Updated

Google’s low- and medium-resolution satellite imagery has gotten a comprehensive update with new imagery from the Landsat 8 satellite. It’s the first such update to its seamless, cloud-free mosaic in three years. The Atlantic has detailed coverage (that helpfully points out, among other things, that this doesn’t apply to the highest zoom levels: those images come from DigitalGlobe satellites and aerial photography).

Lake Poopó Dries Up

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Lake Poopó has become the Aral Sea of the Andes. Thanks to drought, water diversion and mining activity, the lake—long, wide, shallow, saline and the second-largest in Bolivia—has basically dried up, as this comparison of 2013 and 2016 Landsat 8 images demonstrates. CBC NewsThe Independent.

New Year’s Flooding in the Midwest

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These two Landsat images illustrate the extent of flooding along the Wabash and Illinois Rivers at the end of last year, as 6-10 inches of rain fell over the midwestern United States. The image from 8 December 2015, above left, shows normal water levels; the image from 1 January  2016, above right, shows the rivers in flood. Use the slider to compare the two views. Original image. [via]