NATurelle CATastrophes .net – Research points to the existence of rapid droughts

Like flash floods, sudden droughts occur quickly, drying the soil in days or weeks. These events can destroy crops and cause great economic losses. And according to scientists, the speed at which the landscape is drying up has increased.

An iconic example: the drought that hit the central United States in August 2012. It only lasted a few days, but suddenly all the water on the ground ran out. These droughts are brief, therefore less severe and more difficult to detect. However, when they fall at a key time for agriculture. In the US Midwest, 2012 completely wiped out corn crops, causing an estimated loss of more than $ 35 billion.

Researchers at the University of Texas at Austin, Hong Kong Polytechnic University and Texas University of Technology found that while the number of rapid droughts has remained stable over the past two decades, more of them are happening more quickly. Globally, the fastest-growing droughts, which have sent drought-prone areas in just five days, have risen by 3 to 19 percent. And in places especially prone to sudden droughts, such as South Asia, Southeast Asia and Central North America, this increase is between 22 and 59 percent.

Rising global temperatures are likely to be blamed for the rapid onset, said UT Jackson School co-author and professor Zong-Liang Yang, who added that the results of the study point to the importance of to understand sudden droughts and prepare for their effects. “Every year we see record warming attacks, and that’s a good precursor to these rapid droughts,” he said. “The hope and goal of this research is to minimize adverse effects. The research was published in Nature Communication. The study was led by PhD student Yamin Qing and Professor Shuo Wang, both of whom Hong Kong Polytechnic University.

Instant droughts are relatively new to science, with advances in remote sensing technology over the past two decades that have helped reveal cases of rapid soil drying. This serves as a telltale sign of the onset of a rapid drought and can cause drought conditions to appear unexpectedly.

As its name suggests, sudden droughts are short-lived, usually lasting only a few weeks or months. But when they occur during critical growth periods, they can be a disaster. For example, in the summer of 2012, a sudden drought in the central United States caused the corn crop to wither, causing an estimated loss of $ 35.7 billion.

In this study, scientists analyzed global hydroclimate data sets that use satellite-based soil moisture measurements to capture a global picture of instantaneous drought and its evolution over the past 21 years. The data showed that about 34-46% of sudden droughts occurred in about five days. The rest appear in a month, with more than 70% development in half a month or so.

When they analyzed droughts over time, they noticed that fast droughts happened faster.

The study also revealed the importance of humidity and variable weather conditions, with sudden droughts that are more likely when there is a change from humid to arid conditions. As a result, regions experiencing seasonal changes in humidity, such as Southeast Asia, the Amazon Basin, and the east coast and Gulf Coast of the United States, experience hot spots.

“We need to pay special attention to vulnerable regions with a high probability of soil drought and simultaneous atmospheric aridity,” Wang said.

Mark Svoboda, director of the National Drought Mitigation Center and creator of the term “instant drought,” said advances in drought detection technology and modeling tools, such as those used in this study, they have provoked a growing awareness of the influence. and impact of sudden droughts. He said the next big step is to translate that knowledge into field planning.

“You can go back and see how this drought evolves in 2012 and then compare it to the evolution of this tool,” said Svoboda, who was not part of the study. “We really have the groundwork to do a better job of monitoring these droughts.”

The study was funded by the National Natural Science Foundation of China and the Hong Kong Research Grants Council.

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