Ancient lakes and rivers unearthed in Arabia's vast desert dating to around 9,000 years ago

Amazing stuff! Climate change has been going on for millennia not only since the Industrial Revolution as so many demagogues want us to believe!

That is what I call extreme weather events! 😊

"The desert that we see today in Arabia was once a region that repeatedly underwent ‘green’ periods in the past, as a result of periods of high rainfall, resulting in the formation of lakes and rivers around 9,000 years ago. 

This is the key finding from an international, interdisciplinary team that documented an ancient water-sculpted landscape in the Empty Quarter, one of the largest and driest deserts in the world today.   ..."

From the abstract:

"Abundant geomorphological, biological, and isotopic records show that Arabia repeatedly underwent significant climate-driven environmental changes during late Quaternary humid periods. Precisely mapping how the enhancement and expansion of the African Monsoon during these humid periods have affected landscape evolution and human occupation dynamics in Arabia remains a scientific challenge.

Here we reconstruct an ancient water-sculpted landscape consisting of lake and river deposits, coupled with a large outlet valley in the Rub’ al Khali Desert of Saudi Arabia.

During the peak of the Holocene Humid Period or before, intense rainfall reactivated alluvial floodplains and filled a ~1100 km² topographic depression, which eventually breached, carving a deep ~150 km-long valley.

Coupling geologic reconstructions with transient Earth system model simulations shows that this hydrological activity was linked to higher seasonal precipitation punctuated by repeated heavy events. 

Analysis of lacustrine and fluvial sedimentary deposits implies sediment routing across distances of up to 1000 km from the Asir Mountains. Our results indicate that such intense flooding challenges the conventional view of simple, weak, and linear landscape stabilization following increased rainfall in Arabia.

Our findings highlight the crucial role of an enhanced African Monsoon in driving rapid landscape transformations in the Arabian Desert."

Ancient lakes and rivers unearthed in Arabia's vast desert

Unearthing the lush, vibrant past of the world’s largest desert (original news release)

Monsoonal imprint on late Quaternary landscapes of the Rub’ al Khali Desert (open access)

Fig. 1: Distribution of palaeohydrological and geomorphic records, archaeological sites, modeled streams, major monsoon systems, and the study site in Arabia.

Fig. 6: Inferred palaeolake levels based on geomorphic observations.

China is slowly greening its deserts by building a 3,000 km green belt around the desert

Good news!

Extra CO2 in the atmosphere certainly helps! Therefore, China is also building hundreds of coal fired power plants! Caution: satire!

"China’s arid northwest is becoming slightly less so. Late last month, workers completed a 2,000-mile ring of trees around China’s Taklamakan Desert, the latest milestone in a 46-year effort to control desertification. The initiative appears to be making incremental progress: Reuters reports that 26.8 percent of China’s land is currently desert, down from 27.2 percent ten years ago."

Weekly Progress Roundup - by Malcolm Cochran - Doomslayer

China completes 3,000-km green belt around its biggest desert, state media says

Seismic detectors measure soil moisture in the desert using traffic noise

Amazing stuff! Except it depends on "pre-existing fiber-optic cables"!

"... Scientists have figured out a way to measure soil moisture by detecting the vibrations of traffic noise travelling through the ground.

The technique is called distributed acoustic sensing (DAS) and it is normally used to measure seismic waves during earthquakes.

Seismological instruments have never been used to measure soil moisture at such a large scale for such an extended and continuous timespan before.

Researchers in the US repurposed a DAS system to measure moisture content in a part of the Earth known as the vadose zone. This is the shallow region between the underground water table (where the soil is fully saturated) and the surface. ...

In DAS, laser pulses are sent along unused, underground fibre-optic cables. This light bends and refracts as vibrations, such as seismic waves, pass through the cable. Measuring this tells researchers important information about the passing wave.

DAS can also be used to pick up the vibrations of ambient noise caused by humans. The more moisture there is in the vadose zone, the slower these vibrations move through it. ..."

From the abstract:

"Vadose zone soil moisture is often considered a pivotal intermediary water reservoir between surface and groundwater in semi-arid regions. Understanding its dynamics in response to changes in meteorologic forcing patterns is essential to enhance the climate resiliency of our ecological and agricultural system. However, the inability to observe high-resolution vadose zone soil moisture dynamics over large spatiotemporal scales hinders quantitative characterization. Here, utilizing pre-existing fiber-optic cables as seismic sensors, we demonstrate a fiber-optic seismic sensing principle to robustly capture vadose zone soil moisture dynamics. Our observations in Ridgecrest, California reveal sub-seasonal precipitation replenishments and a prolonged drought in the vadose zone, consistent with a zero-dimensional hydrological model. Our results suggest a significant water loss of 0.25 m/year through evapotranspiration at our field side, validated by nearby eddy-covariance based measurements. Yet, detailed discrepancies between our observations and modeling highlight the necessity for complementary in-situ validations. Given the escalated regional drought risk under climate change, our findings underscore the promise of fiber-optic seismic sensing to facilitate water resource management in semi-arid regions."

Seismic detectors measure soil moisture in the desert

Seismic Detectors Measure Soil Moisture Using Traffic Noise "Caltech researchers have developed a new method to measure soil moisture in the shallow subterranean region between the surface and underground aquifers. This region, called the vadose zone, is crucial for plants and crops to obtain water through their roots. However, measuring how this underground moisture fluctuates over time and between geographical regions has traditionally relied on satellite imaging, which only gives low-resolution averages and cannot penetrate below the surface. Additionally, moisture within the vadose zone changes rapidly—a thunderstorm can saturate a region that dries out a few days later."

Fiber-optic seismic sensing of vadose zone soil moisture dynamics (open access)

Fig. 1: Conceptual model for the vadose zone water dynamics and time-lapse seismology example on Ridgecrest DAS array.

Desert Dreams: Celebrating Five Seasons in the Sonoran Desert

I have not seen it yet. However, this could be a stunning film!

Desert Dreams: Celebrating Five Seasons in the Sonoran Desert | Arizona PBS