Early warnings for floods in South Africa: Engineering for future climate change

If the forecast system works, African cities need significant on the ground support. Credit: Shutterstock

Severe weather, rain and flooding are at the forefront of the minds of many South Africans, especially those in KwaZulu-Natal. Early last week (11–12 April 2022), the province’s coast received heavy rain, with some areas recording over 300mm in 24 hours. This is about a third of the annual rainfall in KwaZulu-Natal.

The rain was caused by a strong cut-off low weather system off the east coast of southern Africa. Cut-off lows frequently occur off this coast during the autumn months. These systems can cause localized flooding as well as large wave events.

The port city of Durban (in the municipality of eThekwini) has experienced flooding events almost every year since 2016. Storms responsible for these floods typically dropped 100mm–150mm of rain in 24 hours, according to the eThekwini data portal.

Between 11–12 April 2022, a storm system dropped even more rain than that. It caused devastating floods, landslides, and loss of life. It is natural to ask whether the recent floods in the area will occur more often within the context of climate change or whether they were simply freak events. It is not possible to state conclusively that this storm was a result of climate change. However, scientists believe these types of intense weather systems will occur more frequently in the future.

Perhaps more pertinent is the question: did anyone see this coming? There isn’t a simple answer. It’s something that has been challenging scientists and engineers around the world for decades. For example scientists like myself have been trying to apply the principles of fluid mechanics to address these types of questions.

This is important because if we can predict the occurrence of an event, we can arm disaster management teams with life-saving information.

Predicting flooding

Predicting flooding is not new and consists of two methods. The first relies on historical rainfall and flood records that come from weather stations and river gauges. South Africa has many of these stations throughout the country. It is vital that these stations are properly maintained.

The second method involves computer modeling. It is difficult to predict where rain will fall, how much will fall and whether this will cause flooding. These processes depend on spatial gradients that are not resolved in regional climate models. For example wind moves from high pressure to low pressure, sometimes bringing with it rain. However the wind speed (and how quickly the rain arrives) depends on the difference between the high and low pressure. This is typically very difficult to model accurately. Advances in computer power will likely be able to address this in the future.

Predicting where the water will flow once it reaches the ground is also challenging. Some water infiltrates the soil and flows as groundwater, while some water runs along the surface (called surface runoff). Both the surface and groundwater runoff contribute to the water flowing in rivers. If the ground is saturated, there is less infiltration and more surface water will flow into rivers, causing more flooding. Increased surface runoff also contributes to landslides and erosion. Hardened impermeable surfaces in cities and residential areas also cause increasing . Storm duration is another factor that can influence flooding.

All these factors can combine to drive significant flood events.

How do engineers and city managers develop plans to respond in real-time to these events? A possible answer lies in developing forecast early warning systems. There are good examples in the Netherlands.

Forecast early warning system

The eThekwini coastal, stormwater and catchment management department has developed a forecast early warning system in conjunction with the University of KwaZulu-Natal and the Dutch engineering research institute Deltares. The design incorporates weather forecasting, flood prediction and coastal modeling. The goal of the system is to alert authorities to to provide them with temporal and spatial information to guide decision making. An example of a system like this is the Global Storm Surge Information System.

The department’s engineers and managers have deployed hundreds of rain, weather, water level and coastal monitoring gauges throughout the region that provide authorities with real-time information. The system is still in a and requires resource investment from , South African universities and local authorities.

The works by downscaling output from global modeling centers such as the European Center for Medium-Range Weather Forecasts and National Centers for Environmental Prediction. This data is fed into numerical models that predict flooding and coastal processes at regional and local scales.

The European Center model did predict severe , about three days before the flood. The National Centers model did not. This highlights the difficulties in predicting weather and any decision making that follows.

Observations from the recent flood event suggest there is still a long way to improve and further develop the system. This will rely on improved data sharing between government departments, universities and communities. Currently this isn’t easy in South Africa, for policy reasons. Furthermore, government and local authorities must invest in city engineering staff and technical decision-makers.

Lastly, even if the forecast system works, African cities of the future need significant “on the ground” support in the form of disaster management teams such as police, rescue workers, paramedics and places of shelter.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Early warnings for floods in South Africa: Engineering for future climate change (2022, April 20)
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Early English lessons have lasting effects

In Germany, children start to learn english in primary school. Credit: RUB, Marquard

An international research team has examined how English lessons in primary school affect language proficiency in this subject in secondary school. Children who started learning English in the first grade of primary school performed significantly better in listening and reading comprehension in grade nine than children who started in grade three. The study was a continuation of an earlier paper that had only covered the period up to the seventh grade and couldn’t find any such learning advantage.

The team headed by Professor Markus Ritter from Ruhr-Universität Bochum (RUB) and Dr. Nils Jäkel from the University of Oulu, Finland, in cooperation with Dr. Michael Schurig from the Technical University of Dortmund, describes their findings in the journal System. The study will be published in the June 2022 edition, but is already freely accessible online. The researchers are collaborating within the university consortium UNIC: European University of Post-Industrial Cities.

Data from North Rhine-Westphalia

The study included data from around 3,000 students who participated in a conducted in North Rhine-Westphalia, Germany, between 2010 and 2014. The same data had also been used in the previous study, the results of which the researchers had published in 2017. At that time, they had compared two cohorts, one of which had started English lessons in grade one, the other in grade three. In grades five and seven, they had compared both cohorts in terms of English reading and listening comprehension. The new analysis incorporated another set of data collected in 2016 to measure the English performance of the same in grade nine.

The previous study had found that children who had started English lessons earlier in performed worse in reading and listening comprehension in grade seven than children who had not started English lessons until grade three. However, the new analysis showed that, in grade nine, the early starters in English performed better than the late starters in English.

Additional background variables such as gender, language of origin or could not account for the difference between the poorer performance in the and the late learning gains in the ninth grade.

Transition between school types decisive

“We believe the most plausible explanation is that lessons following the transition period in have been increasingly adapted to the needs of children who start to take English lessons at an early stage,” concludes Nils Jäkel, formerly at RUB, now at the University of Oulu.

“This explanation is in line with research that considers the transition between school types to play a key role in the long-term success of English language education across school boundaries.”

With this in mind, it is crucial to optimize the didactic coordination and alignment of English classes at the intersection of school types. In addition, it may be that pupils benefit in the long run from more implicit language lessons in primary school.

“We see a high need for research to elaborate factors for successful language education, and we recommend well-coordinated, evidence-based measures in overall,” say the researchers.

More information:
Nils Jaekel et al, The impact of early foreign language learning on language proficiency development from middle to high school, System (2022). DOI: 10.1016/j.system.2022.102763

Early English lessons have lasting effects (2022, March 18)
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Hexbyte Glen Cove Early long-distance trade links shaped Siberian dogs, study finds thumbnail

Hexbyte Glen Cove Early long-distance trade links shaped Siberian dogs, study finds

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Nenets dogs of the Siberian Arctic resting beside a dogsled in the Iamal-Nenets region of Siberia. Credit: Robert J. Losey.

Archeological finds show that people in the Arctic regions of Northwestern Siberia had already established long-range trading links with Eurasian populations some 2000 years ago. The initiation of trading relationships was one of a series of significant social changes that took place during this period. Moreover, these changes even had an impact on the genomes of Siberian dogs, as an international team of researchers led by LMU palaeogeneticist Laurent Frantz has now demonstrated. Based on extensive genetic analyses, the team concludes that dogs were imported into the Siberian Arctic, and that this process ultimately led to the establishment of Siberian breeds such as the samoyed.

Genomes dating from the Stone Age to the Holocene

The researchers analyzed the genomes of 49 dogs from sites in Siberia and Eurasia dating to between 60 and about 11,000 years ago. Four of the dogs originated from Ust-Polui, where Russian and Canadian archeologists have uncovered the remains of more than 100 dogs dating back to about 2000 years ago. Numerous finds indicate that this site on the remote Yamal peninsula in Northwestern Siberia was in use—most probably for ceremonial purposes—over a period of about 400 years.

“Some of the dogs found there appear to have been intentionally buried,” says Dr. Robert Losey, from the University of Alberta, and lead archeologist of the study. “But there is also evidence which suggests that many were eaten. Dogs were used for a variety of purposes—not only as a means of transport, but potentially also hunting partners and as sources of food.”

The artifacts uncovered in Ust-Polui include glass beads and objects made of metal, which cannot have been fabricated locally. They must have been sourced from the steppe zone, the Black Sea region or the Near East. Therefore, the people who lived on the Yamal peninsula must have been integrated into long-range trading networks more than 2000 years ago. This was also a time of significant social and technological change—as indicated by the exploitation of iron ore and artifacts related to reindeer harnessing both being evidenced at the site. Large-scale reindeer pastoralism, now widely practiced by Indigenous people in this region, emerged here only in the last few centuries.

Dogs as trade goods

The new genetic analyses revealed that dogs were also among the goods imported into the Siberian Arctic imported from areas further to the south at this time. “Whereas Arctic dogs evolved in isolation prior to at least 7000 years ago, genomic DNA isolated from Siberian dogs dated to between the Iron Age and medieval times shows that there were increasing portions of genetic material derived from dogs from the Eurasian steppes, as well as Europe,” says Dr. Tatiana Feuerborn, the lead author on the paper based at the University of Copenhagen. Thus, the proportion of non-Siberian ancestry among dogs on the Yamal peninsula increased significantly during this period. “Dogs were potentially valuable possessions, and they were bought and sold,” says Frantz. On the other hand, human genomes in Arctic Siberia remained quite stable over this long stretch of time, and there is little sign of genetic input from non-Arctic populations.

The authors of the new study assume that the import of dogs from farther afield is a reflection of societal transitions in Siberia. “The first dogs domesticated in the Arctic served primarily as sledding dogs,” says Frantz. “When Siberian populations turned to pastoralism, they may well have required dogs that had other useful behavioral traits, which were better suited for reindeer herding. The mixing of Arctic dogs with other populations potentially led to the establishment of dog lineages that were both suited to herding and also adapted to the harsh climatic conditions.”

From working dog to samoyed

This strategy of cross-breeding and selection for improved traits eventually led to the emergence of modern Siberian canine lineages such as the samoyed. “A large fraction of the samoyed genome can be traced back to ancestral Arctic bloodlines,” says Frantz, “but it also shows far more Western influence than the husky, for instance.” Because very little subsequent hybridization with other breeds has occurred in the meantime, yet samoyeds have remained largely unchanged since the Middle Ages. In contrast, most other modern breeds result from the targeted efforts of breeders during the 19th and 20th centuries. Only when polar explorers such as Ernest Shackleton obtained dogs from the Arctic and began to breed from them did the samoyed acquire its modern name. “Prior to that they were simply a population of working ,” says Frantz.

The study is published in the Proceedings of the National Academy of Sciences.

More information:
Modern Siberian dog ancestry was shaped by several thousand years of Eurasian-wide trade and human dispersal, Proceedings of the National Academy of Sciences, 2021. www.pnas.org/cgi/doi/10.1073/pnas.2100338118

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Hexbyte Glen Cove Early land plants evolved from freshwater algae, fossils reveal thumbnail

Hexbyte Glen Cove Early land plants evolved from freshwater algae, fossils reveal

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A new assemblage of fossil spores of Lower Ordovician age, about 480 Ma, are intermediate in character between controversial Cambrian forms and well-accepted plant spores from later Ordovician and Silurian deposits. This linkage aligns fossil spores with molecular data and helps explain why megafossil plants axes don’t appear in the geological record until 75 million years later during the Silurian. Credit: Paul Strother

The world may need to start thinking differently about plants, according to a new report in the journal Science by researchers who took a fresh look at spore-like microfossils with characteristics that challenge our conventional understanding about the evolution of land plants.

Found in rock samples retrieved in Australia more than 60 years ago, the microfossils dating to the Lower Ordovician Period, approximately 480 million years ago, fill an approximately 25-million-year gap in knowledge by reconciling the molecular clock—or pace of evolution—with the fossil spore record—the physical evidence of early plant life gathered by scientists over the years.

This reconciliation supports an evolutionary-developmental model connecting plant origins to freshwater green algae, or charophyte algae, said Boston College paleobotanist Paul Strother, a co-author of the new report. The “evo-devo” model posits a more nuanced understanding of plant evolution over time, from simple cell division to initial embryonic stages, rather than large jumps from one species to another.

“We found a mix of fossils linking older, more problematic spore-like microfossils with younger spores that are clearly derived from ,” said Strother. “This helps to bring the fossil spore record into alignment with molecular clock dates if we consider the of land plants as a long-term process involving the evolution of embryonic development.”

The fossil record preserves direct evidence of the evolutionary assembly of the plant regulatory and developmental genome, Strother added. This process starts with the evolution of the plant spore and leads to the origin of plant tissues, organs, and eventually macroscopic, complete plants—perhaps somewhat akin to mosses living today.

“When we consider spores as an important component of the evolution of land plants, there is no longer a gap in the fossil record between molecular dating and fossil recovery,” Strother said. Absent that gap, “we have a much clearer picture of a whole new evolutionary step: from simple cellularity to complex multicellularity.”

As a result, researchers and the public may need to re-think how they view the origin of terrestrial plants—that pivotal advance of life from water to land, said Strother.

A new assemblage of fossil spores of Lower Ordovician age, about 480 Ma, are intermediate in character between controversial Cambrian forms and well-accepted plant spores from later Ordovician and Silurian deposits. This linkage aligns fossil spores with molecular data and helps explain why megafossil plants axes don’t appear in the geological record until 75 million years later during the Silurian. Credit: Paul Strother

“We need to move away from thinking of the origin of land plants as a singularity in time, and instead integrate the fossil record into an evo-devo model of genome assembly across millions of years during the Paleozoic Era—specifically between the Cambrian and Devonian divisions within that era,” Strother said. “This requires serious re-interpretation of problematic fossils that have previously been interpreted as fungi, not plants.”

Strother and co-author Clinton Foster, of the Australian National University, set out to simply describe an assemblage of spore-like microfossils from a deposit dating to the Early Ordovician age—approximately 480 million years ago. This material fills in a gap of approximately 25 million years in the fossil spore record, linking well-accepted younger plant spores to older more problematic forms, said Strother.

Strother and Foster examined populations of fossil spores extracted from a rock core drilled in 1958 in northern Western Australia. These microfossils are composed of highly resistant organic compounds in their cell walls that can structurally survive burial and lithification. They were studied at Boston College, and at the ANU’s Research School of Earth Sciences, with standard optical light microscopy.

“We use fossil spores extracted from rock drill cores to construct an evolutionary history of plants going back in time to the very origin of plants from their algal ancestors,” said Strother. “We have independent age control on these rock samples, so we study evolution by looking at changes in the kinds of spores that occur over time.”

Molecular biologists also look at evolutionary history through time by using genes from living plants to estimate the timing of plant origins using “molecular clocks”—a measurement of evolutionary divergence based on the average rate during which mutations accumulate in a species’ genome.

However, there are huge discrepancies, up to tens of millions of years, between direct fossil data and dates, said Strother. In addition, there are similar time gaps between the oldest spores and when actual whole plants first occur.

These gaps resulted in hypotheses about a “missing fossil record” of the earliest land ,” said Strother.

“Our work seeks to resolve some of these questions by integrating the fossil spore record into an evolutionary developmental model of plant origins from algal ancestors,” Strother said.

More information:
A fossil record of land plant origins from charophyte algae, Science (2021). science.sciencemag.org/lookup/ … 1126/science.abj2927

Early land plants evolved from freshwater algae, fossils reveal (2021, August 12)
retrieved 12 August 2021
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