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» Black Rock Playa, Nevada, USA
 

In a desolate corner of Nevada, a playa surrounded by rugged mountains and described as dry, dusty, desolate, and devoid of vegetation comes to life the week before Labor Day every year for a unique arts festival.

Black Rock Playa in northwestern Nevada is part of the lakebed of ancient Lake Lahontan, a deep lake that existed as recently as 15,000 years ago. Lake Lahontan left fine sediments on the lake bottom to form the extremely flat surface. According to a detailed topographic study, the elevation of the playa varies by just 1 meter over 310 square kilometers.

The playa stretches 56 kilometers from the small town of Gerlach toward the northeast and the edge of the Black Rock Range.

Rainfall is rare during summer when daily high temperatures regularly exceed 37°C, making the surface hard-packed and dusty. Snowmelt flows into the playa in the spring to smooth out the surface. The clay minerals on the lakebed expand when wet and then contract as they dry to form a cracked pattern.

Black Rock Playa is managed by the Bureau of Land Management (BLM) as The Black Rock Desert–High Rock Canyon Emigrant Trails National Conservation Area.

Map of the featured area.

A unique event takes place every year on the playa. Burning Man is a weeklong arts and culture festival that ends on the Saturday of Labor Day weekend with the burning of a huge wooden effigy.

Part of the event is the construction of a temporary metropolis named Black Rock City. Building of the temporary town starts about 6 weeks before the event. This is the most visible product of the event in satellite images.

Besides the city’s radial roadways, the images show a pentagon surrounding the city. This “trash fence” catches wind-blown garbage to keep it from spreading throughout the playa. A major policy of Burning Man is to leave no trace. All debris must be cleaned up after the event is over. Participants must pick up all MOOP, which stands for Matter Out Of Place. The BLM, which grants the license for the event, monitors the cleanup.

A Landsat 8 image from October 16, 2018, shows not only the temporary nature of the metropolis but also that cleanup is evidently still in progress on that date.

Burning Man began in 1986 in California with 20 attendees and a 2.4-meter effigy. The festival’s first year at Black Rock Playa was in 1990, when the event had outgrown its California beach location. The temporary city that year had a population of 350 and the effigy was 12 meters tall. The 2018 event included 70,000 people. In recent years, the height of the entire effigy has exceeded 30 meters.

Usually located in the southern portion of the playa, the festival location changes slightly every year. Can you find the festival location in the 1996 image? (Look in the upper right of that image.) How about in 1999? (Extreme southwestern part of the playa.)

The city becomes easier to spot as the event grows larger. In the 2018 image, Black Rock City spans nearly 5 kilometers across. But its area covers only about 3 percent of the entire playa.

The BLM sets a population limit of 70,000 on the temporary city.

As dry and dusty as the playa is when it comes time for Burning Man in late summer, it’s often wet during winter and early spring. Mean annual precipitation in the playa is about 17 centimeters, but water also flows into the playa from melting snow in the mountains to form shallow lakes of varying size.

The shortwave infrared and near-infrared bands on the Landsat sensors accentuate water and the land-water boundary. The silty water on the playa pops in bright aqua in the images. The frequent flooding and drying keeps the playa surface firm.

It is possible, though rare, for lakes to stay through an entire calendar year, such as from fall 1983 to spring 1985. A September 16, 1984, Landsat image shows the playa as still wet. Most other years, the lakes dry up by midsummer.

An image from May 4, 1993, shows an interesting effect. Water from that year’s temporary lake was blown out of its bed to the north by a strong south wind. A shallow scarp, only 20–40 centimeters high, curves around the north edge of the playa and often marks the edge of the lake. But the blue color washes over the scarp in this image.

On the other hand, the playa occasionally does not flood at all. If that happens for a few years in a row, the surface can become soft and loose, as happened from 2002 to 2004 when the playa remained dry. After two springs (2005 and 2006) of lake formation and desiccation, flooding restored the surface to a hard and durable crust.

If lake formation on the playa becomes less frequent in the future, it could become a source of dust emissions. In this relatively remote area, remote sensing with satellites provides an efficient means to monitor hydrologic conditions.

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