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Imaggeo on Mondays: The Crossroads of Flood and Drought

Imaggeo on Mondays: The Crossroads of Flood and Drought

This picture was taken on the way back from collecting field measurements at the Lordsburg Playa in southwestern New Mexico, USA. The setting sun highlights the contrast between the dry, cracked soil and the standing water from antecedent rainfall.

A playa is a flat topographic depression in arid or semi-arid regions that contains a large amount of deposited sediment. When the surface of the playa is dry, this deposited sediment is exposed and at risk of being entrained into the atmosphere by wind.

With an extent of approximately 250 square kilometers, Lordsburg Playa is a dust ‘hot spot’ in the southwestern Unites States. Dust events originating from the playa are normally small, but they can contain high dust concentrations and occur frequently during the dry season in spring.

The Lordsburg Playa is of particular interest to the local population, as the interstate highway I-10 crosses over the region. Under windy conditions, dust emissions from the playa can drastically reduce visibility on the highway and cause severe traffic accidents.

In October 2016, I went on a one-week field trip to the playa, installing a temporary measurement site to study local dust emission mechanisms. At that time, parts of the playa were still flooded from summer monsoon precipitation. During the field trip, we observed a local, but strong dust event. The event started in the morning and peaked at around 9:00 am when visibility was reduced to a few meters for a short time. Fortunately, the dust was blown northward during this event and the highway was not affected. Visibility recovered shortly after, but small-scale dust phenomena such as dust plumes and dust devils occurred almost continuously during most of the day.

By Martina Klose, a post-doctoral researcher at the Barcelona Supercomputing Center (BSC) in Spain

Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their photographs and videos to this repository and, since it is open access, these images can be used for free by scientists for their presentations or publications, by educators and the general public, and some images can even be used freely for commercial purposes. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. Submit your photos at http://imaggeo.egu.eu/upload/.

Imaggeo on Mondays: a storm is coming

Imaggeo on Mondays: a storm is coming

Coastlines globally are immensely diverse: from the beautifully topical and sun kissed beaches of the Caribbean, to the wet and misty British coastline, through to the raw and wild Alaskan shores, they are home to scores of flora and fauna; rich habitats shaped by powerful forces of nature.

In stark contrast, some coastlines, (28,000 km worldwide to be precise) are dry almost barren places, where little grows. These long stretches of inhospitable seaside lands are known as hyperarid and arid coastlines. Due to the lack of protective vegetation the land is exposed to the action of winds and the sun, leaving behind pavements of bare rock, large dune formations and/or highly saline enclosed lakes (sebkhas).

The Gulf of Aqaba, in the north-western tip of Saudi Arabia, where the desert meets the Red Sea is one such place. Rivers here, which drain into the sea water, are fleeting. They appear after heavy rainfall, when flash floods deliver huge influxes of sediment to the coral-rich waters of the Red Sea.

Nadine Hoffman took today’s featured image while driving from Israel from the Red Sea. Pictured is the northern tip of Saudi Arabia, where a spring storm is coming into the desert bringing severe rain and flash floods. Eventually, the flood waters will drain into the Gulf of Aqaba.

 

If you pre-register for the 2017 General Assembly (Vienna, 22 – 28 April), you can take part in our annual photo competition! From 1 February up until 1 March, every participant pre-registered for the General Assembly can submit up three original photos and one moving image related to the Earth, planetary, and space sciences in competition for free registration to next year’s General Assembly! These can include fantastic field photos, a stunning shot of your favourite thin section, what you’ve captured out on holiday or under the electron microscope – if it’s geoscientific, it fits the bill. Find out more about how to take part at http://imaggeo.egu.eu/photo-contest/information/.

Imaggeo on Mondays: Dune ridge perspective

Imaggeo on Mondays: Dune ridge perspective

Imagine taking a hike over soft, ever shifting sands. This is exactly what Martina Klose, a researcher at USDA, did when she captured this beautiful photograph. While most of us will likely think of deserts as inhospitable and static landscapes, they can tell us much about dune forming processes, as Martina explains in today’s blog post.

The photograph shows the view down from the crest of a megadune in the Badain Jaran Desert in China. It was taken during a two-day field trip in the course of the International Conference on Aeolian Research (ICAR) VIII, which took place in Lanzhou, China, in 2014.

Aeolian processes are wind-generated processes, such as the emission, transport, and deposition of sediment

The Badain Jaran desert is located north of the Hexi Corridor in western Inner Mongolia and is one of the largest areas of shifting sands in China. With maximum dune heights of a few hundred meters, the Badain Jaran Sand Sea hosts some of the largest megadunes in the world. The sand sea is not only dry, however – amongst the dunes are a number of lakes of various sizes, creating a picturesque environment. You can see what it looks like from space by following the link to this NASA satellite image!

In general, wind is the driving force for dune formation. In the case of the Badain Jaran Sand Sea, the local topography and the subsurface water source are likely additional factors contributing to the development and evolution of the dune fields.

After a long bus drive on the way to the sand sea, climbing one of the giant dunes was a welcoming exercise for most of the conference participants – rewarded with a stunning view from the dune crest and optionally a fun slide down the dune slope.

 By Martina Klose, USDA-ARS Jornada Experimental Range

Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their photographs and videos to this repository and, since it is open access, these images can be used for free by scientists for their presentations or publications, by educators and the general public, and some images can even be used freely for commercial purposes. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. Submit your photos at http://imaggeo.egu.eu/upload/.