UK’s climate change readiness has made ‘significant progress’
by Renee Karunungan on May 4, 2022
There is significant progress in the UK for reporting and implementing climate change adaptation, according to a new study led by TyndallUEA’s Katie Jenkins. Katie has created an Adaptation Inventory of adaptation actions happening based on official records of adaptation projects being implemented by both public and private sector, accompanied by a systematic review of the peer-reviewed literature of adaptation case studies.
Adapting to climate change means taking action to prepare for and adjust to current and predicted effects of climate change. Adaptation plays an important role in managing past, present and future climate risk and impacts. However, there is an “adaptation gap” where the distance between existing adaptation efforts versus adaptation needs is widening, according to the United Nations Environment Programme’s Adaptation Gap Report. Tracking national adaptation plans is deemed critical to support future decision-making and drive future actions.
According to the Committee’s assessment, adaptation planning for 2C and 4C global warming is not happening, and that the gap between future risks and planned adaptation has widened, delivering the minimum level of resilience.
Katie’s new Adaptation Inventory provides insight on what is currently being implemented, which helps policymakers and practitioners learn from existing knowledge and practical case studies.
“The Adaptation Inventory provides a consistent and easily searchable database which will continue to evolve. It can provide evidence on the specific types of adaptation implemented on the ground as well as provide more detailed insight into the specific examples of action being implemented. This has the potential to help and inform UK-based decision-making,” Katie said.
The Adaptation Inventory identifies and documents current and planned adaptation in the UK, and how it is being implemented through adaptation actions, the sectors where adaptation is occurring, and where the gaps remain. There were 360 adaptation actions identified in the Inventory, comprising 134 adaptation types. Out of these 360 adaptation actions, 80% have already been implemented.
The private sector accounts for 74% of the actions with water companies dominating. Regulatory frameworks, standards, and reporting requirements are key drivers required by water companies by the Regulator. For example, water companies are already required to plan their resilience to drought.
The most common types of adaptation actions are flood protection (12%), leakage reduction (4%), water metering (3%), property level flood protection (3%), operational improvements (3%), and back-up generators (3%). Most actions were categorized as structural and physical interventions. Other interventions were categorized as technological and ecosystem based.
The Adaptation Inventory also looks at the types of climate hazards being addressed. It found that 76% of the actions were in response to drought, 26% for extreme rainfall, 13% for flooding, and 11% for higher temperatures. One example of adaptation for drought is rainwater recovery using storage facilities available on the site, reducing the demand for fresh water during drought. For alleviating flooding, a water company is using afforestation. The London Underground has doubled the capacity of ventilation shafts on the Victoria line, which provide more air flow on hot days.
The Brain Bank has released findings from its first three years of operation, analyzing the brains of professional and non-professional athletes who donate them after death.
The researchers say 12 of the athletes’ brains showed signs of chronic traumatic encephalopathy (CTE), a condition associated with a range of psychiatric problems, ranging from mood and behavior disorders to cognitive impairment and dementia.
“CTE was identified in the brains of older former professionals with long playing careers, but also in younger, non-professional sportsmen and in recent professionals who had played under modern concussion guidelines,” the authors found.
“Screening for CTE in all deaths by suicide is probably impractical, but our finding suggests it should be undertaken if a history of repetitive head injury is known or suspected,” the authors say.
The authors note that brains donated to the bank are more likely to show signs of trauma because donation is often done when an athlete’s family have concerns about the role head trauma may have played in a person’s death or condition.
Nonetheless, they say: “Our findings should encourage clinicians and policymakers to develop measures that further mitigate the risk of sport-related repetitive head injury.”
One Step Closer to Hydrogen-Fueled Planes
Airbus to Test Zero-Emissions Aircraft, but How Does It Work?
Hydrogen fuel, touted by some as the fuel of the future, is seen as a potential solution for the deeply polluting aviation and shipping industries in a net-zero world: hydrogen burns cleanly, producing just energy and water vapor.
But while engineers have promoted hydrogen as a possible transport fuel since at least the 1920s, real-world technologies are still in their infancy, thanks to the destructive dominance of fossil fuels over the last century.
Airbus’ announcement, then, marks an important early step in a move towards making the sector compatible with net-zero.
“This is the most significant step undertaken at Airbus to usher in a new era of hydrogen-powered flight since the unveiling of our ZEROe concepts back in September 2020,” said Sabine Klauke, Airbus Chief Technical Officer, in a statement.
“By leveraging the expertise of American and Europeanengine manufacturers to make progress on hydrogen combustion technology, this international partnership sends a clear message that our industry is committed to making zero-emission flight a reality.”
“Our ambition is to take this aircraft and add a stub in between the two rear doors at the upper level,” said Glenn Llewellyn, Airbus’ Vice President of Zero Emissions Aircraft, in a promotional video on YouTube. “That stub will have on the end of it a hydrogen powered gas turbine.”
There will be instruments and sensors around the hydrogen storage unit and engine, to monitor how the system functions both in ground tests and in-flight. Up in the cockpit, instruments will need to be modified with a new throttle to change the amount of power the engine operates at, and a display for pilots to monitor the system.
Why Hydrogen Fuel?
Hydrogen, the most abundant element in the Universe, burns cleanly, and can be produced using renewable energy through the electrolysis of water (though it can be produced using fossil fuels, too).
Given that it’s so abundant, can be made from water, and combusts to produce water vapor, it can be a closed-loop energy system; the definition of renewable.
It’s also highly reactive: hydrogen gas, made up of two hydrogen atoms, can combust at extremely low concentrations. It can combust in response to a simple spark, and it’s even been known to combust when exposed to sunlight or minor increases in temperature. That’s why it’s a suitable replacement fuel for kerosene, but it’s also why the system needs to be tested for safety.
“Aviation is one of these things that everyone agrees needs hydrogen for decarbonization, because it’s not going to be possible to electrify long distance air travel in the next few decades,” explains Fiona Beck, a senior lecturer at ANU and convener of the Hydrogen Fuels Project in the University’s Zero-carbon energy for the Asia Pacific grand challenge. “We just don’t have the battery technologies.
“One kilogram of hydrogen has 130 times the energy of one kilogram of batteries, so in something like air travel, where weight is really important, there’s just no way you’re going to get batteries light enough to directly electrify air travel.”
That’s a very high-profile incident in which hydrogen proved deadly, but a proverbial boatload of hydrogen gas encased within a fabric covering is nothing like the fuel cells proponents of hydrogen fuel are creating in the modern era.
Nonetheless, the incident demonstrates why it’s important to ensure the safety and impregnability of fuel storage; a single spark can prove fatal (though that’s the case with existing fuels, too).
“The key will be to have really good storage containers for the hydrogen, and you’re going to have to re-engineer all the fuel delivery lines,” says Beck, “because you can’t assume that the systems that deliver kerosene safely to an engine are going to be suitable for delivering hydrogen.”
Ultimately, Beck says pre-existing, sophisticated hydrogen technologies, even if they aren’t derived from aviation, mean engineers aren’t going into this blind.
“We already use quite a lot of hydrogen in industry, which is very different than flying a plane full of hydrogen, but still, we know how to handle it relatively safely.
“So, it’s just about designers and engineers making sure that they consider all the safety aspects of it. It’s different, but not necessarily more challenging.”
Two Paths to a Hydrogen Fueled Future of Flight?
Beck notes that Airbus aren’t the only commercial entity exploring hydrogen as a fuel type. In fact, Boeing are incorporating hydrogen into their vision of a cleaner future, but in a different way.
“There’s a difference between just getting hydrogen and burning it in a modified jet engine and what Boeing are doing, which is using sustainable air fuels,” she says.
But what are sustainable air fuels (SAFs)? Beck says they’re made by combining hydrogen with carbon dioxide to make a sustainably-produced kerosene.
“The difference is that instead of getting fossil fuels and refining them, you start with hydrogen, which you would hope comes from green sources, and then you take some carbon dioxide captured from another industrial process, and you’re cycling the carbon dioxide one more time before it gets released.”
So, CO2 is still released into the atmosphere, but the individual flight is not adding its own new load of greenhouse gases to the amount. Instead, it essentially piggy-backs off a pre-existing quantity of emissions that were already produced somewhere else.
The type of fuel that wins out remains to be seen.
“It’ll be really interesting to see which approach we go for in the longer term,” Beck muses. “With synthetic air fuels, your plane engine doesn’t need to change at all, nothing about the demand side needs to change–it’s just kerosene.
“But then there’s issues, because you’re still using carbon dioxide.”
Some commentators see Boeing’s bet on SAFs as a more pragmatic approach that may help us usher in a less polluting age, quicker. On the other hand, if successful, the Airbus system can be fully carbon-neutral from fuel production through to combustion.
“Climate Adaptation by Itself Is Not Enough”: The Latest IPCC Report Installment
The Second of Three Reports Shows Our Vulnerabilities and How We Can Protect Them.
In the next part of its Sixth Assessment Report, released today, the IPCC has examined the world population’s vulnerability to climate change, and what must be done to adapt to current and future changes.
It’s the second of three sections of this report (Working group II)–Working Group I’s section, released last August, demonstrates that anthropogenic climate change is continuing, while Working Group III’s component, on mitigation, will be released in April. An overall report is coming in September.
The IPCC reports represent a phenomenal amount of work from hundreds of researchers and government officials. It synthesizes information from over 10,000 studies, with over 62,000 comments from expert peer reviewers.
Literally every sentence of the summary for policymakers has been agreed upon by consensus from a group of experts and government delegations–the line-by-line approval process alone takes a fortnight. The report in its entirety is a product of several years.
Given the time and expertise involved in making the report, its conclusions aren’t revelatory: the world is becoming increasingly vulnerable to the effects of climate change, poorest people are often the most at risk, and adaptation to these effects will force changes in our lifestyle, infrastructure, economy and agriculture.
While adaptation is necessary, it’s also insufficient. “It’s increasingly clear that the pace of adaptation across the globe is not enough to keep up with climate change,” says Professor Mark Howden, Working Group II’s vice-chair and director of the Institute for Climate, Energy & Disaster Solutions at the Australian National University.
Under the IPCC’s projected emissions scenarios, the climate could warm much more or slightly more, based on the volume of greenhouse gas released into the atmosphere.
“Depending on which of those trajectories we go on, our adaptation options differ,” says Howden.
On our current, business-as-usual trajectory, we can’t avoid the crisis, no matter how much we change our human systems to prepare for or recover from the ravages of climate change.
“Climate adaptation, risk management, by itself is not enough,” says Howden.
The report comes at a pertinent time for Australia, as southern Queensland and northern New South Wales experience dramatic flooding from high, La Niña-related rainfall.
“One of the clear projections is an increase in the intensity of heavy rainfall events,” says Professor Brendan Mackey, director of National Climate Change Adaptation Research Facility at Griffith University, and a lead author on the Australasian chapter of the report.
Mackey also notes that he has extended family members in Lismore, NSW, who today needed to be rescued from their rooftops as the town floods.
Howden says that while it’s hard to link individual disasters to climate change as they occur, he agrees that there are more floods projected for northern Australia.
“I think we can say that climate change is already embedded in this event,” adds Howden.
“These events are driven by, particularly, ocean temperatures, and we know very well that those have gone up due to climate change due to human influence.”
He points out that flooding is a common side effect of a La Niña event, of which more are expected as the climate warms.
Flooding is not the only extreme weather event that can be linked to climate change.
“We’ve observed further warming and sea level rise, we’ve observed more flood days and heat waves, we’ve observed less snow,” says Mackey.
“Interestingly, [we’ve observed] more rainfall in the north, less winter rainfall in the southwest and southeast, and more extreme fire weather days in the south and east.”
All of these trends are expected to continue, especially under high-emissions scenarios.
For Australians, the predictions the IPCC has made with very high or high confidence include: both a decline in agricultural production and increase in extreme fire weather across the south of the continent; a nation-wide increase in heat-related mortality; increased stress on cities, infrastructure and supply chains from natural disasters; and inundation of low-lying coastal communities from sea level rise.
The final high-confidence prediction is that Australian institutions and governments aren’t currently able to manage these risks.
“Climate change impacts are becoming more complex and difficult to manage,” says Professor Lauren Rickards, director of the Urban Futures Enabling Capability Platform at RMIT, also a lead author on the Australasian chapter.
“Not only are climatic hazards becoming more severe–including, sometimes, nonlinear effects such as, for example, tipping over flood levees that have historically been sufficient–but also those climatic hazards are intersecting in very, very complex ways. And in turn, the flow-on effects on the ground are interacting, causing what’s called cascading and compounding impacts.”
She adds that many local and state governments and the private sector have both recognized the importance of changing their practices to prepare for or react to climate extremes.
“We have these systems, these infrastructural systems–energy, transport, water, communications, for example–and it’s the need to adapt those at the base of a lot of the adaptation that’s needed,” says Rickards.
Australia is missing a large investment in research on how different places and systems can adapt to the changing climate.
“We’ve seen a really significant reduction in the research into what actions different individuals, communities, sectors, can take,” says Howden.
“And what that means is we don’t have the portfolio of options available for people in a way that is easily communicable, and easily understood, and easily adopted.”
Without this research, as well as work from local and Indigenous experts, some adaptations can even risk worsening the impacts of climate change.
“The evidence that we’ve looked at shows really clearly that adaptation strategies, when they build on Indigenous and local knowledge and integrate science, that’s when they are most successful,” says Dr. Johanna Nalau, leader of the Adaptation Science Research Theme at Cities Research Institute, Griffith University.
While the risks Australia faces are dramatic, things are much worse for other parts of the world. Nalau, who was a lead author on the report’s chapter on small islands, says that “most of the communities and countries are constrained in what they can do in terms of adaptation”.
In April, we will have access to the IPCC’s dossier on mitigating climate change and emissions reduction. But in the meantime, Working Group II’s battalion of researchers advocate for better planning for climate disaster, more research into ways human systems can adapt, sustainable and just development worldwide, and rapid emissions reduction.
“Adaptation can’t be divorced from mitigation, conceptually or in practice,” says Rickards.
“We need adaptation to enable effective mitigation. We need effective mitigation to enable adaptation to give it a chance of succeeding. At present, we’re not on track and we need to pivot quickly.”
Piecing Together Pandemic Origins
New Research Asserts Market, Not Laboratory, Is the “Unambiguous” Birthplace of SARS-CoV-2
by Jamie Priest
Now in our third year of woe, most of us are naturally focused on the end of the pandemic. The global death toll is approaching 6 million, and the world is desperately searching for signs the ordeal’s over.
But amid the future watching, a team of researchers have turned their attention back to the beginning, tackling the question that was once on everyone’s lips: where did SARS-CoV-2 originate?
Outlining their evidence in two preprints, researchers assert an “unambiguous” origin in the Huanan market in Wuhan, spilling over not once, but twice into the human population and kicking off a global health crisis.
The paired papers, which have yet to undergo peer review and publication in a scientific journal, critically undermine the competing, and controversial, alternative origin story that involves a leak–intentional or otherwise–from a nearby Wuhan virology lab where scientists study coronaviruses.
The Huanan market was an immediate suspect when COVID first emerged in late 2019. Workers at the market were amongst the first individuals to present with the pneumonia that was quickly linked to a novel coronavirus, and Chinese officials, fearing a repeat of the 2002 SARS epidemic that killed 774 people, were quick to close the market down.
But by the time Chinese researchers descended on the Huanan market in 2020 to collect genetic samples, they found no wildlife present at all. Although they were able to detect traces of the virus in samples taken from surfaces and sewers in the market, the lack of direct evidence of infection in market animals sparked a debate over whether this truly was the epicenter of the outbreak. Alternative theories centered around the Wuhan Institute of Virology.
In the face of this absence of evidence, researchers working on the new reports turned to alternative information sources.
Using data pulled from the Chinesesocial media app Weibo, they were able to map the location of 737 COVID-positive Wuhan residents who turned to the app to seek health advice during the first three months of the outbreak.
Plotting the geographic concentrations of cases through time, the researchers clearly identified the market as the centre of origin, with the virus spreading radially through surrounding suburbs and across the city as time progressed. Through statistical analysis, the researchers demonstrated that the chances of such a pattern arising through mere chance was exceedingly unlikely.
However, the pattern alone was open to interpretation, with questions remaining about pathways of introduction to the market–was the virus carried in inside a caged animal, on the coat of an unwitting scientist, or via some as-yet unidentified vector?
To dig further into the mystery, the researchers looked at the genetic samples obtained from market surfaces in January 2020 by Chinese scientists, tracing the locations of individual positive samples to their exact location within the market complex.
This second map revealed a strong concentration of positive samples in one corner of the market, a sector that had been previously documented to house a range of wild mammals that are considered potential coronavirus hosts.
Finally, the researchers created an evolutionary family tree of the earliest coronavirus lineages that emerged in the first few panicked weeks of the pandemic.
Even in its very earliest stages SARS-CoV-2 was a variable beast, with evidence of two distinct lineages, dubbed A and B. Looking closely at the mutations that separate the two, the researchers found something surprising–rather than one descending from the other, it appears that they had separate origins and entries into the human population, with lineage B making the leap in late November and lineage A following suit shortly afterwards.
Initial studies of the Huanan market genetic samples found only lineage B, but this latest investigation detected the presence of lineage A in people who lived in close proximity to the market–a finding corroborated by a recent Chinese study that identified lineage A on a single glove collected from the market during the initial shutdown.
Questions remain about the identity of the intermediary animal host species. But by narrowing research focus to the most likely centre of origin, this research will significantly aid efforts to understand the process that saw COVID-19 enter the world, and hopefully help avert future pandemics.
Fake Viral Footage Is Spreading alongside the Real Horror in Ukraine—Here Are 5 Ways to Spot It
Manipulated or Falsified Videos and Images Can Spread Quickly—but There Are Strategies You Can Take to Evaluate Them.
By TJ Thompson, Daniel Angus and Paul Dootson
Amid the alarming images of Russia’s invasion of Ukraine over the past few days, millions of people have also seen misleading, manipulated or false information about the conflict on social media platforms such as Facebook, Twitter, TikTok and Telegram.
One example is this video of military jets posted to TikTok, which is historical footage but captioned as live video of the situation in Ukraine.
Visuals, because of their persuasive potential and attention-grabbing nature, are an especially potent choice for those seeking to mislead. Where creating, editing or sharing inauthentic visual content isn’t satire or art, it is usually politically or economically motivated.
Disinformation campaigns aim to distract, confuse, manipulate and sow division, discord, and uncertainty in the community. This is a common strategy for highly polarized nations where socioeconomic inequalities, disenfranchisement and propaganda are prevalent.
How is this fake content created and spread, what’s being done to debunk it, and how can you ensure you don’t fall for it yourself?
What Are the Most Common Fakery Techniques?
Using an existing photo or video and claiming it came from a different time or place is one of the most common forms of misinformation in this context. This requires no special software or technical skills—just a willingness to upload an old video of a missile attack or other arresting image, and describe it as new footage.
Another low-tech option is to stage or pose actions or events and present them as reality. This was the case with destroyed vehicles that Russia claimed were bombed by Ukraine.
Using a particular lens or vantage point can also change how the scene looks and can be used to deceive. A tight shot of people, for example, can make it hard to gauge how many were in a crowd, compared with an aerial shot.
Taking things further still, Photoshop or equivalent software can be used to add or remove people or objects from a scene, or to crop elements out from a photograph. An example of object addition is the below photograph, which purports to show construction machinery outside a kindergarten in eastern Ukraine. The satirical text accompanying the image jokes about the “calibre of the construction machinery”—the author suggesting that reports of damage to buildings from military ordinance are exaggerated or untrue.
Close inspection reveals this image was digitally altered to include the machinery. This tweet could be seen as an attempt to downplay the extent of damage resulting from a Russian-backed missile attack, and in a wider context to create confusion and doubt as to veracity of other images emerging from the conflict zone.
Journalists and fact-checkers are also working to verify content and raise awareness of known fakes. Large, well-resourced news outlets such as the BBC are also calling out misinformation.
Social media platforms have added new labels to identify state-run media organisations or provide more background information about sources or people in your networks who have also shared a particular story.
They have also tweaked their algorithms to change what content is amplified and have hired staff to spot and flag misleading content. Platforms are also doing some work behind the scenes to detect and publicly share information on state-linked information operations.
What Can I Do about It?
You can attempt to fact-check images for yourself rather than taking them at face value. An article we wrote late last year for the Australian Associated Press explains the fact-checking process at each stage: image creation, editing and distribution.
Here are five simple steps you can take:
Examine the metadata
This Telegram post claims Polish-speaking saboteurs attacked a sewage facility in an attempt to place a tank of chlorine for a “false flag” attack.
But the video’s metadata—the details about how and when the video was created—show it was filmed days before the alleged date of the incident.
To check metadata for yourself, you can download the file and use software such as Adobe Photoshop or Bridge to examine it. Online metadata viewers also exist that allow you to check by using the image’s web link.
One hurdle to this approach is that social media platforms such as Facebook and Twitter often strip the metadata from photos and videos when they are uploaded to their sites. In these cases, you can try requesting the original file or consulting fact-checking websites to see whether they have already verified or debunked the footage in question.
If old content has been recycled and repurposed, you may be able to find the same footage used elsewhere. You can use Google Images or TinEye to “reverse image search” a picture and see where else it appears online.
But be aware that simple edits such as reversing the left-right orientation of an image can fool search engines and make them think the flipped image is new.
Look for inconsistencies
Does the purported time of day match the direction of light you would expect at that time, for example? Do watches or clocks visible in the image correspond to the alleged timeline claimed?
You can also compare other data points, such as politicians’ schedules or verified sightings, Google Earth vision or Google Maps imagery, to try and triangulate claims and see whether the details are consistent.
Ask yourself some simple questions
Do you know where, when and why the photo or video was made? Do you know who made it, and whether what you’re looking at is the original version?
Using online tools such as InVID or Forensically can potentially help answer some of these questions. Or you might like to refer to this list of 20 questions you can use to “interrogate” social media footage with the right level of healthy skepticism.
Ultimately, if you’re in doubt, don’t share or repeat claims that haven’t been published by a reputable source such as an international news organization. And consider using some of these principles when deciding which sources to trust.
By doing this, you can help limit the influence of misinformation, and help clarify the true situation in Ukraine.
A famous face or tune or quip or saying or photo constitutes the raw material for a shared cultural understanding around the world. Everybody somehow knows “James Bond” or “Mercedes” or “Big Ben” in London or the “Eiffel Tower” in Paris.
“Kanał” means sewer, and the story takes place in the sewers of Warsaw as this band of resistance fighters tries to avoid being killed by the Germans who still have overwhelming military superiority in weapons, ammunition, etc.
At one point these fighters enter a Polish “bourgeois” home (i.e., great wealth is on display) and one of them, Michal, the classical musician, played by Sheybal (whom you will have seen as a villain in James Bond movies) goes over to the piano they find, a Bechstein, and “plays around” including the famous tango from Uruguay and Argentina, “La cumparsita” (the little parade) which went “viral” (for its time) around 1916-1917 “radiating out” from Uruguay and Argentina.
In the 1959 film Some Like It Hot, “La cumparsita” is played by a blindfolded Cuban band during a scene in which Jack Lemmon dressed in drag dances with overstated flair in the arms of Joe E. Brown who thinks Lemmon is a woman (“Daphne—you’re leading again”). During the filming in 1958, actor George Raft taught the other two men to dance the tango for this scene.
Students should realize as part of an education, thought of in the sense we are introducing here, that the world is an “ambient” ecosystem of these cultural icons, memes and tropes and one should be attune to them and how they connect the world into something like a semi-shared experience.
Notice, say, that the Bechstein piano, played by Michal (Vladek Sheybal) in the movie Kanał (he later goes mad and playing an ocarina, starts reciting lines from Dante and loses his mind) is the name of the Bechstein family which were instrumental in the rise of Hitler. The irony should be part of the student’s viewing experience and should show how “screwy” the world is.
Notice too that there’s an ocarina-playing character in the movie Stalag 17 who’s described as mentally unwell.
All of these aspects are part of the material world and the iconic world and the world of “signs” that are part of our education, understood as ambience of which the campus is one part only.
Summary: Using airborne laser, 400 million snow depth measurements at Hardangervidda in Southern Norway have been collected. The amount of data has made in-depth studies of the spatial distribution of snow and its interaction with the terrain and vegetation possible. We find that the terrain variability, expressed by the square slope, the average amount of snow, and whether the terrain is vegetated or not, largely explains the variation of snow depth. With this information it is possible to develop equations that predict snow depth variability that can be used in environmental models, which again are used for important tasks such as flood forecasting and hydropower planning. One major advantage is that these equations can be determined from the data that are, in principle, available everywhere, provided there exists a detailed digital model of the terrain.
by Christine L. Dolph, Evelyn Boardman, Mohammad Danesh-Yazdi, Jacques C. Finlay, Amy T. Hansen, Anna C. Baker & Brent Dalzell
Abstract: When phosphorus from farm fertilizer, eroded soil, and septic waste enters our water, it leads to problems like toxic algae blooms, fish kills, and contaminated drinking supplies. In this study, we examine how phosphorus travels through streams and rivers of farmed areas. In the past, soil lost from farm fields was considered the biggest contributor to phosphorus pollution in agricultural areas, but our study shows that phosphorus originating from fertilizer stores in the soil and from crop residue, as well as from soil eroded from sensitive ravines and bluffs, contributes strongly to the total amount of phosphorus pollution in agricultural rivers. We also found that most phosphorus leaves farmed watersheds during the very highest river flows. Increased frequency of large storms due to climate chaos will therefore likely worsen water quality in areas that are heavily loaded with phosphorus from farm fertilizers. Protecting water in agriculturalwatersheds will require knowledge of the local landscape along with strategies to address (1) drivers of climate chaos, (2) reduction in the highest river flows, and (3) ongoing inputs and legacy stores of phosphorus that are readily transported across land and water.
by Matteo Giuliani, Marta Zaniolo, Andrea Castelletti, Guido Davoli & Paul Block
Abstract: Increasingly variable hydrologic regimes combined with more frequent and intense extreme events are challenging water systems management worldwide. These trends emphasize the need of accurate medium- to long-term predictions to timely prompt anticipatory operations. Despite in some locations global climate oscillations and particularly the El Niño Southern Oscillation (ENSO) may contribute to extending forecast lead times, in other regions there is no consensus on how ENSO can be detected, and used as local conditions are also influenced by other concurrent climate signals. In this work, we introduce the Climate State Intelligence framework to capture the state of multiple global climate signals via artificial intelligence and improve seasonal forecasts. These forecasts are used as additional inputs for informing water system operations and their value is quantified as the corresponding gain in system performance. We apply the framework to the Lake Como basin, a regulated lake in northern Italy mainly operated for flood control and irrigation supply. Numerical results show the existence of notable teleconnection patterns dependent on both ENSO and the North Atlantic Oscillation over the Alpine region, which contribute in generating skillful seasonal precipitation and hydrologic forecasts. The use of this information for conditioning the lake operations produces an average 44% improvement in system performance with respect to a baseline solution not informed by any forecast, with this gain that further increases during extreme drought episodes. Our results also suggest that observed preseason sea surface temperature anomalies appear more valuable than hydrologic-based seasonal forecasts, producing an average 59% improvement in system performance.
by Daniel J. Short Gianotti, Guido D. Salvucci, Ruzbeh Akbar, Kaighin A. McColl, Richard Cuenca & Dara Entekhabi
Abstract: Surface soil moisture measurements are typically correlated to some degree with changes in subsurface soil moisture. We calculate a hydrologic length scale, λ, which represents (1) the mean-state estimator of total column water changes from surface observations, (2) an e-folding length scale for subsurface soil moisture profile covariance fall-off, and (3) the best second-moment mass-conserving surface layer thickness for a simple bucket model, defined by the data streams of satellite soil moisture and precipitation retrievals. Calculations are simple, based on three variables: the autocorrelation and variance of surface soil moisture and the variance of the net flux into the column (precipitation minus estimated losses), which can be estimated directly from the soil moisture and precipitation time series. We develop a method to calculate the lag-one autocorrelation for irregularly observed time series and show global surface soil moisture autocorrelation. λ is driven in part by local hydroclimate conditions and is generally larger than the 50-mm nominal radiometric length scale for the soil moisture retrievals, suggesting broad subsurface correlation due to moisture drainage. In all but the most arid regions, radiometricsoil moisture retrievals provide more information about ecosystem-relevant water fluxes than satellite radiometers can explicitly “see”; lower-frequency radiometers are expected to provide still more statistical information about subsurface water dynamics.
by Jordan S. Read, Xiaowei Jia, Jared Willard, Alison P. Appling, Jacob A. Zwart, Samantha K. Oliver, Anuj Karpatne, Gretchen J. A. Hansen, Paul C. Hanson, William Watkins, Michael Steinbach & Vipin Kumar
Abstract: The rapid growth of data in water resources has created new opportunities to accelerate knowledge discovery with the use of advanced deep learning tools. Hybrid models that integrate theory with state-of-the art empirical techniques have the potential to improve predictions while remaining true to physical laws. This paper evaluates the Process-Guided Deep Learning (PGDL) hybrid modeling framework with a use-case of predicting depth-specific lake water temperatures. The PGDL model has three primary components: a deep learning model with temporal awareness (long short-term memory recurrence), theory-based feedback (model penalties for violating conversation of energy), and model pre-training to initialize the network with synthetic data (water temperature predictions from a process-based model). In situ water temperatures were used to train the PGDL model, a deep learning (DL) model, and a process-based (PB) model. Model performance was evaluated in various conditions, including when training data were sparse and when predictions were made outside of the range in the training data set. The PGDL model performance (as measured by root-mean-square error (RMSE)) was superior to DL and PB for two detailed study lakes, but only when pretraining data included greater variability than the training period. The PGDL model also performed well when extended to 68 lakes, with a medianRMSE of 1.65 °C during the test period (DL: 1.78 °C, PB: 2.03 °C; in a small number of lakes PB or DL models were more accurate). This case-study demonstrates that integrating scientific knowledge into deep learning tools shows promise for improving predictions of many important environmental variables.
by Qiang Dai, Qiqi Yang, Dawei Han, Miguel A. Rico-Ramirez & Shuliang Zhang
Abstract:Radar-gauge rainfall discrepancies are considered to originate from radarrainfall measurements while ignoring the fact that radar observes rain aloft while a rain gauge measures rainfall on the ground. Observations of raindrops observed aloft by weather radars consider that raindrops fall vertically to the ground without changing in size. This premise obviously does not stand because raindrop location changes due to wind drift and raindrop size changes due to evaporation. However, both effects are usually ignored. This study proposes a fully formulated scheme to numerically simulate both raindrop drift and evaporation in the air and reduces the uncertainties of radarrainfall estimation. The Weather Research and Forecasting model is used to simulate high-resolution three-dimensional atmospheric fields. A dual-polarization radar retrieves the raindrop size distribution for each radarpixel. Three schemes are designed and implemented using the Hameldon Hillradar in Lancashire, England. The first considers only raindrop drift, the second considers only evaporation, and the last considers both aspects. Results show that wind advection can cause a large drift for small raindrops. Considerable loss of rainfall is observed due to raindropevaporation. Overall, the three schemes improve the radar-gauge correlation by 3.2%, 2.9%, and 3.8% and reduce their discrepancy by 17.9%, 8.6%, and 21.7%, respectively, over eight selected events. This study contributes to the improvement of quantitative precipitation estimation from radarpolarimetry and allows a better understanding of precipitation processes.
by K. Zhao, Z. Gong, F. Xu, Z. Zhou, C. K. Zhang, G. M. E. Perillo & G. Coco
Abstract: We develop a process-based model to simulate the geomorphodynamic evolution of tidal channels, considering hydrodynamics, flow-induced bank erosion, gravity-induced bank collapse, and sediment dynamics. A stress-deformation analysis and the Mohr-Coulomb criterion, calibrated through previous laboratory experiments, are included in a model simulating bank collapse. Results show that collapsed bank soil plays a primary role in the dynamics of bank retreat. For bank collapse with small bank height, tensile failure in the middle of the bank (Stage I), tensile failure on the bank top (Stage II), and sectional cracking from bank top to the toe (Stage III) are present sequentially before bank collapse occurs. A significant linear relation is observed between bank height and the contribution of bank collapse to bank retreat. Contrary to flow-induced bank erosion, bank collapse prevents further widening since the collapsed bank soil protects the bank from direct bank erosion. The bank profile is linear or slightly convex, and the planimetric shape of tidal channels (gradually decreasing in width landward) is similar when approaching equilibrium, regardless of the consideration of bank erosion and collapse. Moreover, the simulated width-to-depth ratio in all runs is comparable with observations from the Venice Lagoon. This indicates that the equilibrium configuration of tidal channels depends on hydrodynamic conditions and sediment properties, while bank erosion and collapse greatly affect the transient behavior (before equilibrium) of the tidal channels. Overall, this contribution highlights the importance of collapsed bank soil in investigating tidal channel morphodynamics using a combined perspective of geotechnics and soil mechanics.
by Yunquan Wang, Oliver Merlin, Gaofeng Zhu & Kun Zhang
Abstract: While numerous models exist for soilevaporation estimation, they are more or less empirically based either in the model structure or in the determination of introduced parameters. The main difficulty lies in representing the water stress factor, which is usually thought to be limited by capillarity-supported water supply or by vapor diffusion flux. Recent progress in understanding soil hydraulic properties, however, have found that the film flow, which is often neglected, is the dominant process under low moisture conditions. By including the impact of film flow, a reexamination on the typical evaporation process found that this usually neglected film flow might be the dominant process for supporting the Stage II evaporation (i.e., the fast falling rate stage), besides the generally accepted capillary flow-supported Stage I evaporation and the vapor diffusion-controlled Stage III evaporation. A physically based model for estimating the evaporation rate was then developed by parameterizing the Buckingham-Darcy’s law. Interestingly, the empirical Bucket model was found to be a specific form of the proposed model. The proposed model requires the in-equilibrium relative humidity as the sole input for representing water stress and introduces no adjustable parameter in relation to soil texture. The impact of vapor diffusion was also discussed. Model testing with laboratory data yielded an excellent agreement with observations for both thin soil and thick soil column evaporation experiments. Model evaluation at 15 field sites generally showed a close agreement with observations, with a great improvement in the lower range of evaporation rates in comparison with the widely applied Priestley and Taylor Jet Propulsion Laboratory model.
by Carmelo Juez, C. Schärer, H. Jenny, A. J. Schleiss & M. J. Franca
Abstract: Overbank sedimentation is predominantly due to fine sediments transported under suspension that become trapped and settle in floodplains when high-flow conditions occur in rivers. In a compound channel, the processes of exchanging water and fine sediments between the main channel and floodplains regulate the geomorphological evolution and are crucial for the maintenance of the ecosystem functions of the floodplains. These hydrodynamic and morphodynamic processes depend on variables such as the flow-depth ratio between the water depth in the main channel and the water depth in the floodplain, the width ratio between the width of the main channel and the width of the floodplain, and the floodplain land cover characterized by the type of roughness. This paper examines, by means of laboratoryexperiments, how these variables are interlinked and how the deposition of sediments in the compound channel is jointly determined by them. The combination of these compound channel characteristics modulates the production of vertically axised large turbulent vortical structures in the mixing interface. Such vortical structures determine the water mass exchange between the main channel and the floodplain, conditioning in turn the transport of sediment particles conveyed in the water, and, therefore, the resulting overbank sedimentation. The existence and pattern of sedimentation are conditioned by both the hydrodynamic variables (the flow-depth ratio and the width ratio) and the floodplain land cover simulated in terms of smooth walls, meadow-type roughness, sparse-wood-type roughness, and dense-wood-type roughness.
by D. F. Gold, P. M. Reed, B. C. Trindade & G. W. Characklis
Summary: Cooperation among neighboring urban water utilities can help water managers face challenges stemming from climate change and population growth. Water utilities can cooperate by coordinating water transfers and water restrictions in times of water scarcity (drought) so that water is provided to areas that need it most. In order to successfully implement these policies, however, cooperative partners must find a compromise that is acceptable to all regional actors, a task complicated by asymmetries in resources and risks often present in regional systems. The possibility of deviations from agreed upon actions is another complicating factor that has not been addressed in water resources literature. Our study focuses on four urban water utilities in the Research Triangle region of North Carolina who are investigating cooperative drought mitigation strategies. We contribute a framework that includes the use of simulation models, optimization algorithms, and statistical tools to aid cooperating partners in finding acceptable compromises that are tolerant modest deviations in planned actions. Our results can be used by regional utilities to avoid or alleviate potential planning conflicts and are broadly applicable to urban regional water supply planning across the globe.
Abstract: Changes in river flow may appear from shifts in land cover, constructions in the river channel, and climatic change, but currently there is a lack of understanding of the relative importance of these drivers. Therefore, we collected gauged river flow time series from 1961 to 2018 from across Sweden for 34 disturbed catchments to quantify how the various types of disturbances have affected river flow. We used trend analysis and the differences in observations versus hydrological modeling to explore the effects on river flow from (1) land cover changes from wildfires, storms, and urbanization; (2) dam constructions with regulations for hydropower production; and (3) climate-change impact in otherwise undisturbed catchments. A mini model ensemble, consisting of three versions of the S-HYPE model, was used, and the three models gave similar results. We searched for changes in annual and daily stream flow, seasonal flow regime, and flow duration curves. The results show that regulation of river flow has the largest impact, reducing spring floods with up to 100% and increasing winter flow by several orders of magnitude, with substantial effects transmitted far downstream. Climate changed the total river flow up to 20%. Tree removal by wildfires and storms has minor impacts at medium and large scales. Urbanization, on the contrary, showed a 20% increase in high flows also at medium scales. This study emphasizes the benefits of combining observed time series with numerical modeling to exclude the effect of varying weather conditions, when quantifying the effects of various drivers on long-term streamflow shifts.
by Matthew A. Thomas, Brian D. Collins & Benjamin B. Mirus
Summary:Soil wetness and rainfall contribute to landslides across the world. Using soil moisture sensors and rain gauges, these environmental conditions have been monitored at numerous points across the Earth’s surface to define threshold conditions, above which landsliding should be expected for a localized area. Satellite-based technologies also deliver estimates of soil wetness and rainfall, potentially offering an approach to develop thresholds as part of landslide warning systems over larger spatial scales. To evaluate the potential for using satellite-based measurements for landslide warning, we compare the accuracy of landslide thresholds defined with ground- versus satellite-based soil wetness and rainfall information. We find that the satellite-based data over-predict soil wetness during the time of year when landslides are most likely to occur, resulting in thresholds that also over-predict the potential for landslides relative to thresholds informed by direct measurements on the ground. Our results encourage the installation of more ground-based monitoring stations in landslide-prone settings and the cautious use of satellite-based data when more direct measurements are not available.
by Giuseppe Brunetti, Radka Kodešová & Jiří Šimůnek
Abstract:Food contamination is responsible for thousands of deaths worldwide every year. Plants represent the most common pathway for chemicals into the human and animal food chain. Although existing dynamic plant uptake models for chemicals are crucial for the development of reliable mitigation strategies for food pollution, they nevertheless simplify the description of physicochemical processes in soil and plants, mass transfer processes between soil and plants and in plants, and transformation in plants. To fill this scientific gap, we couple a widely used hydrological model (HYDRUS) with a multi-compartment dynamic plant uptake model, which accounts for differentiated multiple metabolization pathways in plant’s tissues. The developed model is validated first theoretically and then experimentally against measured data from an experiment on the translocation and transformation of carbamazepine in three vegetables. The analysis is further enriched by performing a global sensitivity analysis on the soil–plant model to identify factors driving the compound’s accumulation in plants’ shoots, as well as to elucidate the role and the importance of soil hydraulic properties on the plant uptake process. Results of the multilevel numerical analysis emphasize the model’s flexibility and demonstrate its ability to accurately reproduce physicochemical processes involved in the dynamic plant uptake of chemicals from contaminated soils.
by Lee R. Harrison, Erin Bray, Brandon Overstreet, Carl J. Legleiter, Rocko A. Brown, Joseph E. Merz, Rosealea M. Bond, Colin L. Nicol & Thomas Dunne
Abstract: Large-scale river restoration programs have emerged recently as a tool for improving spawning habitat for native salmonids in highly altered river ecosystems. Few studies have quantified the extent to which restored habitat is utilized by salmonids, which habitat features influence redd site selection, or the persistence of restored habitat over time. We investigated fall-run Chinook salmon spawning site utilization and measured and modeled corresponding habitat characteristics in two restored reaches: a reach of channel and floodplain enhancement completed in 2013 and a reconfigured channel and floodplain constructed in 2002. Redd surveys demonstrated that both restoration projects supported a high density of salmon redds, 3 and 14 years following restoration. Salmon redds were constructed in coarse gravel substrates located in areas of high sediment mobility, as determined by measurements of gravel friction angles and a grain entrainment model. Salmon redds were located near transitions between pool-riffle bedforms in regions of high predicted hyporheic flows. Habitat quality (quantified as a function of stream hydraulics) and hyporheic flow were both strong predictors of redd occurrence, though the relative roles of these variables differed between sites. Our findings indicate that physical controls on redd site selection in restored channels were similar to those reported for natural channels elsewhere. Our results further highlight that in addition to traditional habitat criteria (e.g., water depth, velocity, and substrate size), quantifying sediment texture and mobility, as well as intragravel flow, provides a more complete understanding of the ecological benefits provided by river restoration projects.
by Katherine H. Markovich, Andrew H. Manning, Laura E. Condon & Jennifer C. McIntosh
Abstract: Mountain-block recharge (MBR) is the subsurface inflow of groundwater to lowland aquifers from adjacent mountains. MBR can be a major component of recharge but remains difficult to characterize and quantify due to limited hydrogeologic, climatic, and other data in the mountain block and at the mountain front. The number of MBR-related studies has increased dramatically in the 15 years since the last review of the topic was conducted by Wilson and Guan (2004), generating important advancements. We review this recent body of literature, summarize current understanding of factors controlling MBR, and provide recommendations for future research priorities. Prior to 2004, most MBR studies were performed in the southwestern United States. Since then, numerous studies have detected and quantified MBR in basins around the world, typically estimating MBR to be 5–50% of basin-fill aquifer recharge. Theoretical studies using generic numerical modeling domains have revealed fundamental hydrogeologic and topographic controls on the amount of MBR and where it originates within the mountain block. Several mountain-focused hydrogeologic studies have confirmed the widespread existence of mountain bedrock aquifers hosting considerable groundwater flow and, in some cases, identified the occurrence of interbasin flow leaving headwatercatchments in the subsurface—both of which are required for MBR to occur. Future MBR research should focus on the collection of high-priority data (e.g., subsurface data near the mountain front and within the mountain block) and the development of sophisticated coupled models calibrated to multiple data types to best constrain MBR and predict how it may change in response to climate warming.
by Mohamed Hayek, Banda S. RamaRao & Marsh Lavenue
Abstract: This work presents an efficient mathematical/numerical model to compute the sensitivity coefficients of a predefined performance measure to model parameters for one-dimensional steady-state sequentially coupled radionuclide transport in a finite heterogeneous porous medium. The model is based on the adjoint sensitivity approach that offers an elegant and computationally efficient alternative way to compute the sensitivity coefficients. The transport parameters include the radionuclide retardation factors due to sorption, the Darcy velocity, and the effective diffusion/dispersion coefficients. Both continuous and discrete adjoint approaches are considered. The partial differential equations associated with the adjoint system are derived based on the adjoint state theory for coupled problems. Physical interpretations of the adjoint states are given in analogy to results obtained in the theory of groundwater flow. For the homogeneous case, analytical solutions for primary and adjoint systems are derived and presented in closed forms. Numerically calculated solutions are compared to the analytical results and show excellent agreements. Insights from sensitivity analysis are discussed to get a better understanding of the values of sensitivity coefficients. The sensitivity coefficients are also computed numerically by finite differences. The numerical sensitivity coefficients successfully reproduce the analytically derived sensitivities based on adjoint states. A derivative-based global sensitivity method coupled with the adjoint state method is presented and applied to a real field case represented by a site currently being considered for underground nuclear storage in Northern Switzerland, “Zürich Nordost,” to demonstrate the proposed method. The results show the advantage of the adjoint state method compared to other methods in term of computational effort.
by C. Ancey, E. Bardou, M. Funk, M. Huss, M. A. Werder & T. Trewhela
Summary: Every year, natural and man-made dams fail and cause flooding. For public authorities, estimating the risk posed by dams is essential to good risk management. Efficient computational tools are required for analyzing flood risk. Testing these tools is an important step toward ensuring their reliability and performance. Knowledge of major historical floods makes it possible, in principle, to benchmark models, but because historical data are often incomplete and fraught with potential inaccuracies, validation is seldom satisfactory. Here we present one of the few major historical floods for which information on flood initiation and propagation is available and detailed: the Giétro flood. This flood occurred in June 1818 and devastated the Drance Valley in Switzerland. In the spring of that year, ice avalanches blocked the valley floor and formed a glacial lake, whose volume is today estimated at 25×106 m3. The local authorities initiated protection works: A tunnel was drilled through the ice dam, and about half of the stored water volume was drained in 2.5 days. On 16 June 1818, the dam failed suddenly because of significant erosion at its base; this caused a major flood. This paper presents a numerical model for estimating flow rates, velocities, and depths during the dam drainage and flood flow phases. The numerical results agree well with historical data. The flood reconstruction shows that relatively simple models can be used to estimate the effects of a major flood with good accuracy.
by Marialaura Bancheri, Francesco Serafin & Riccardo Rigon
Abstract: This work presents a new graphical system to represent hydrological dynamical models and their interactions. We propose an extended version of the Petri Nets mathematical modeling language, the Extended Petri Nets (EPN), which allows for an immediate translation from the graphics of the model to its mathematical representation in a clear way. We introduce the principal objects of the EPN representation (i.e., places, transitions, arcs, controllers, and splitters) and their use in hydrological systems. We show how to cast hydrological models in EPN and how to complete their mathematical description using a dictionary for the symbols and an expression table for the flux equations. Thanks to the compositional property of EPN, we show how it is possible to represent either a single hydrological response unit or a complex catchment where multiple systems of equations are solved simultaneously. Finally, EPN can be used to describe complex Earth system models that include feedback between the water, energy, and carbon budgets. The representation of hydrological dynamical systems with EPN provides a clear visualization of the relations and feedback between subsystems, which can be studied with techniques introduced in nonlinear systems theory and control theory.
by A. de Lavenne, V. Andréassian, G. Thirel, M.-H. Ramos & C. Perrin
Abstract: In semidistributed hydrological modeling, sequential calibration usually refers to the calibration of a model by considering not only the flows observed at the outlet of a catchment but also the different gauging points inside the catchment from upstream to downstream. While sequential calibration aims to optimize the performance at these interior gauged points, we show that it generally fails to improve performance at ungauged points. In this paper, we propose a regularization approach for the sequential calibration of semidistributed hydrological models. It consists in adding a priori information on optimal parameter sets for each modeling unit of the semi-distributed model. Calibration iterations are then performed by jointly maximizing simulation performance and minimizing drifts from the a priori parameter sets. The combination of these two sources of information is handled by a parameter k to which the method is quite sensitive. The method is applied to 1,305 catchments in France over 30 years. The leave-one-out validation shows that, at locations considered as ungauged, model simulations are significantly improved (over all the catchments, the median KGE criterion is increased from 0.75 to 0.83 and the first quartile from 0.35 to 0.66), while model performance at gauged points is not significantly impacted by the use of the regularization approach. Small catchments benefit most from this calibration strategy. These performances are, however, very similar to the performances obtained with a lumped model based on similar conceptualization.
Summary:Droughts lasting longer than 1 year can have severe ecological, social, and economic impacts. They are characterized by below-average flows, not only during the low-flow period but also in the high-flow period when water stores such as groundwater or artificial reservoirs are usually replenished. Limited catchment storage might worsen the impacts of droughts and make water management more challenging. Knowledge on the occurrence of multiyear drought events enables better adaptation and increases preparedness. In this study, we assess the proneness of Europeancatchments to multiyear droughts by simulating long discharge records. Our findings show that multiyear drought events mainly occur in regions where the discharge seasonality is mostly influenced by rainfall, whereas catchments whose seasonality is dominated by melt processes are less affected. The strong link between the proneness of a catchment to multiyear events and its discharge seasonality leads to the conclusion that future changes toward less snow storage and thus less snow melt will increase the probability of multiyear drought occurrence.
by Sina Khatami, Murray C. Peel, Tim J. Peterson & Andrew W. Western
Abstract: Uncertainty analysis is an integral part of any scientific modeling, particularly within the domain of hydrological sciences given the various types and sources of uncertainty. At the center of uncertainty rests the concept of equifinality, that is, reaching a given endpoint (finality) through different pathways. The operational definition of equifinality in hydrological modeling is that various model structures and/or parameter sets (i.e., equal pathways) are equally capable of reproducing a similar (not necessarily identical) hydrological outcome (i.e., finality). Here we argue that there is more to model equifinality than model structures/parameters, that is, other model components can give rise to model equifinality and/or could be used to explore equifinality within model space. We identified six facets of model equifinality, namely, model structure, parameters, performance metrics, initial and boundary conditions, inputs, and internal fluxes. Focusing on model internal fluxes, we developed a methodology called flux mapping that has fundamental implications in understanding and evaluating model process representation within the paradigm of multiple working hypotheses. To illustrate this, we examine the equifinality of runoff fluxes of a conceptual rainfall-runoff model for a number of different Australian catchments. We demonstrate how flux maps can give new insights into the model behavior that cannot be captured by conventional model evaluation methods. We discuss the advantages of flux space, as a subspace of the model space not usually examined, over parameter space. We further discuss the utility of flux mapping in hypothesis generation and testing, extendable to any field of scientific modeling of open complex systems under uncertainty.
Abstract:Floods are the most frequent natural calamity in India. The Godavari river basin (GRB) witnessed several floods in the past 50 years. Notwithstanding the large damage and economic loss, the role of extreme precipitation and antecedent moisture conditions on floods in the GRB remains unexplored. Using the observations and the well-calibrated Variable Infiltration Capacity model, we estimate the changes in the extreme precipitation and floods in the observed (1955–2016) and projected future (2071–2100) climate in the GRB. We evaluate the role of initial hydrologic conditions and extreme precipitation on floods in both observed and projected future climate. We find a statistically significant increase in annual maximum precipitation for the catchments upstream of four gage stations during the 1955–2016 period. However, the rise in annual maximum streamflow at all the four gage stations in GRB was not statistically significant. The probability of floods driven by extreme precipitation (PFEP) varies between 0.55 and 0.7 at the four gage stations of the GRB, which declines with the size of the basins. More than 80% of extreme precipitation events that cause floods occur on wet antecedent moisture conditions at all the four locations in the GRB. The frequency of extreme precipitation events is projected to rise by two folds or more (under RCP 8.5) in the future (2071–2100) at all four locations. However, the increased frequency of floods under the future climate will largely be driven by the substantial rise in the extreme precipitation events rather than wet antecedent moisture conditions.
by Woei Keong Kuan, Pei Xin, Guangqiu Jin, Clare E. Robinson, Badin Gibbes & Ling Li
Abstract:Tides and seasonally varying inland freshwater input, with different fluctuation periods, are important factors affecting flow and salt transport in coastal unconfined aquifers. These processes affect submarine groundwater discharge (SGD) and associated chemical transport to the sea. While the individual effects of these forcings have previously been studied, here we conducted physical experiments and numerical simulations to evaluate the interactions between varying inland freshwater input and tidal oscillations. Varying inland freshwater input was shown to induce significant water exchange across the aquifer-sea interface as the saltwater wedge shifted landward and seaward over the fluctuation cycle. Tidal oscillations led to seawater circulations through the intertidal zone that also enhanced the density-driven circulation, resulting in a significant increase in the total SGD. The combination of the tide and varying inland freshwater input, however, decreased the SGD components driven by the separate forcings (e.g., tides and density). Tides restricted the landward and seaward movement of the saltwater wedge in response to the varying inland freshwater input in addition to reducing the time delay between the varying freshwater input signal and landward-seaward movement in the saltwater wedge interface. This study revealed the nonlinear interaction between tidal fluctuations and varying inland freshwater input will help to improve our understanding of SGD, seawater intrusion, and chemical transport in coastal unconfined aquifers.
