Irrigation management key for bioenergy production to mitigate climate change

Limiting water stress risks: irrigation management key for bioenergy production to mitigate climate change

To avoid a substantial increase in water scarcity, biomass plantations for energy production need sustainable water management, a new study shows. Bioenergy is frequently considered one of the options to reduce greenhouse gases for achieving the Paris climate goals, especially if combined with capturing the CO2 from biomass power plants and storing it underground. Yet growing large-scale bioenergy plantations worldwide does not just require land, but also considerable amounts of freshwater for irrigation – which can be at odds with respecting Earth’s Planetary Boundaries. Scientists now calculated in their to date most detailed computer simulations how much additional water stress could result for people worldwide in a scenario of conventional irrigation and one of sustainable freshwater use.

“Irrigation of future biomass plantations for energy production without sustainable water management, combined with population growth, could double both the global area and the number of people experiencing severe water stress by the end of the century, according to our computer simulations,” says lead author Fabian Stenzel from the Potsdam Institute for Climate Impact Research (PIK) who developed the research idea in the Young Scientists Summer Program of the International Institute for Applied Systems Analysis (IIASA). “However, sustainable water management could almost halve the additional water stress compared to another analyzed scenario of strong climate change unmitigated by bioenergy production.”

Both political regulation and on-farm improvements needed

“Sustainable water management means both political regulation – such as pricing or water allocation schemes – to reduce the amounts of water taken from rivers as well as on-farm improvements to make more efficient use of the water,” says co-author Sylvia Tramberend from IIASA. This could include cisterns for rainwater collection or mulching to reduce evaporation. “Moreover, sustainable water management includes the preservation of reliable river flows to ensure undisturbed ecosystems in and alongside rivers. Up- and downstream river management may in fact require international cooperation calling for more transboundary river management as well as between different water users – that’s the challenge ahead for integrated water resource management.”

Largely unmitigated global warming together with population growth would increase the number of people under water stress by about 80% in the simulations. Enhanced use of bioenergy with carbon capture and storage could limit climate change: When plants grow, they take up CO2 from the air and build it into their trunks, twigs and leaves. If this biomass is burned in power plants and the CO2 is captured from the exhausts and stored underground (carbon capture and storage, in short CCS), this can eventually help reduce the amount of greenhouse gases in our atmosphere – scientists call this ‘negative emissions’.

In many scenarios, these are seen as necessary for meeting ambitious climate mitigation targets if direct emission reductions proceed too slowly, and to balance any remaining greenhouse gas emissions that are difficult or impossible to reduce, for instance potentially in aviation, certain types of industry or in livestock production.

Water scarcity remains a huge challenge

“According to existing scenarios, biomass plantations could increase by up to 6 million square kilometers if global warming is to be limited to 1.5 degrees Celsius by the end of the century, the more ambitious of the two temperature targets of the Paris Agreement,” says co-author Dieter Gerten from PIK. “We use these scenario inputs to run simulations in our high-resolution global vegetation and water balance model to explore the freshwater implications. While substantial irrigation implied in a bioenergy plus CCS scenario including population growth suggests a 100% increase in the number of people facing water stress, combining it with sustainable water management brings the number down to 60%. This, of course, is still an increase, so challenging tradeoffs are on the table.”

Regions that already suffer from water stress today would be most affected in the climate change scenario, like the Mediterranean, the Middle East, northeastern China, South-East and southern West Africa. In the bioenergy plus CCS scenario without sustainable water management, high water stress extends to some otherwise unaffected regions, like the East of Brazil and large parts of Sub-Saharan Africa. Here, large biomass plantation areas in need of irrigation are assumed in the scenario analyzed.

Sustainable Development Goals and Planetary Boundaries must be taken into account

Climate mitigation is one of the Sustainable Development Goals (SDGs) the world has agreed to achieve. The water–energy–environment nexus studied in this research highlights that pathways to sustainability must consider all affected SDGs.  

“The numbers show that either way, sustainable water management is a challenge urgently to be addressed,” says co-author Wolfgang Lucht, head of PIK’s Earth System Analysis research department. „This new study confirms that measures currently considered to stabilize our climate, in this case bioenergy plus CCS, must take into account a number of further dimensions of our Earth system – water cycles are one of them. Risks and tradeoffs have to be carefully considered before launching large-scale policies that establish biomass markets and infrastructure. The concept of Planetary Boundaries considers the whole Earth system, including but not limited to climate. Particularly the integrity of our biosphere must be acknowledged to protect a safe operating space for humanity.” 

FOR MORE INFORMATION: Potsdam Institute for Climate Impact Research (PIK)

Atmospheric drying will lead to lower crop yields, shorter trees across the globe

drying
Atmospheric drying (referred to as water vapor pressure deficit or VPD) is expected to increase as a result of climate change. This could reduce crop yields and make trees shorter. (Credit: Maria H Park).

Global atmospheric drying — known by scientists as a rise in vapor pressure deficit — has been observed worldwide since the early 2000s. In recent years, this concerning phenomenon has been on the rise, and is predicted to amplify even more in the coming decades as climate change intensifies. 

In a new paper published in the journal Global Change Biology, research from the University of Minnesota and Western University in Ontario, Canada, outlines global atmospheric drying significantly reduces productivity of both crops and non-crop plants, even under well-watered conditions. The new findings were established on a large-scale analysis covering 50 years of research and 112 plant species.

“When there is a high vapor pressure deficit, our atmosphere pulls water from other sources: animals, plants, etc.,” said senior author Walid Sadok, an assistant professor in the Department of Agronomy and Plant Genetics at the University of Minnesota. “An increase in vapor pressure deficit places greater demand on the crop to use more water. In turn, this puts more pressure on farmers to ensure this demand for water is met — either via precipitation or irrigation — so that yields do not decrease.”

“We believe a climate change-driven increase in atmospheric drying will reduce plant productivity and crop yields — both in Minnesota and globally,” said Sadok.

In their analysis, researchers suspected plants would sense and respond to this phenomenon in unexpected ways, generating additional costs on productivity. Findings bear out that various plant species — from wheat, corn, and even birch trees — take cues from atmospheric drying and anticipate future drought events.

Through this process, plants reprogram themselves to become more conservative — or in other words: grow smaller, shorter and more resistant to drought, even if the drought itself does not happen. Additionally, due to this conservative behavior, plants are less able to fix atmospheric CO2 to perform photosynthesis and produce seeds. The net result? Productivity decreases.

“As we race to increase production to feed a bigger population, this is a new hurdle that will need to be cleared,” said Sadok. “Atmospheric drying could limit yields, even in regions where irrigation or soil moisture is not limiting, such as Minnesota.”

On a positive note, the analysis indicates different species or varieties within species respond more or less strongly to this drying depending on their evolutionary and genetic make-up. For example, in wheat, some varieties are less responsive to this new stress compared to others, and this type of variability seems to exist within other non-crop species as well.

“This finding is particularly promising as it points to the possibility of breeding for genotypes with an ability to stay productive despite the increase in atmospheric drying,” said Sadok.

Danielle Way, a plant physiologist and co-author of the study from Western University, sees similar outcomes when it comes to ecosystems.

“Variation in plants’ sensitivity to atmospheric drying could also be leveraged to predict how natural ecosystems will respond to climate change and manage them in ways that increase their resilience to climate change,” she said.

In the future, researchers believe these findings can be used to design new crop varieties and manage ecosystems in ways that make them more resilient to atmospheric drying. However, new collaborations are needed between plant physiologists, ecologists, agronomists, breeders and farmers to make sure the right kind of variety is released to farmers depending on their specific conditions.

“Ultimately, this investigation calls for more focused interdisciplinary research efforts to better understand, predict and mitigate the complex effects of atmospheric drying on ecosystems and food security,” Sadok and Way said.

The research was funded by grants from the Minnesota Wheat Research & Promotion Council, the Minnesota Soybean Research and Promotion Council and the Minnesota Department of Agriculture.

FOR MORE INFORMATION: University of Minnesota

Humans control majority of freshwater ebb and flow on Earth, study finds

Reservoirs like this one, Englebright Lake in California, are responsible for more than half of the water storage variability on Earth, a new study finds. Credit: Gary Saxe/Adobe Stock

Humans have made a remarkable impact on the planet, from clearing forests for agriculture and urbanization to altering the chemistry of the atmosphere with fossil fuels. Now, a new study in the journal Nature reveals for the first time the extent of human impact on the global water cycle.

The study used NASA’s Ice, Cloud and Land Elevation Satellite (ICESat-2) to assemble the largest ever dataset of seasonal water levels in more than 227,000 lakes, ponds and reservoirs worldwide. The data reveal that even though human-managed reservoirs comprise only a small percentage of all water bodies, they account for 57% of the total seasonal water storage changes globally.

“We tend to think of the water cycle as a purely natural system: Rain and snowmelt run into rivers, which run to the ocean where evaporation starts the whole cycle again,” said Sarah Cooley, a postdoctoral researcher at Stanford University who launched the research project while a graduate student at Brown University. “But humans are actually intervening substantially in that cycle. Our work demonstrates that humans are responsible for a majority of the seasonal surface water storage variability on Earth.”

Cooley led the work with Laurence Smith, a professor of environmental sciences at Brown, and Johnny Ryan, a postdoctoral researcher at the Institute at Brown for Environment and Society. 

The researchers say the study provides a critical baseline for tracking the global hydrological cycle as climate change and population growth put new stresses on freshwater resources.

An extraordinary dataset

Launched into orbit in 2018, ICESat-2’s primary mission is to track changes in the thickness and elevation of ice sheets around the world. It does so with a laser altimeter, which uses pulses of light to measure elevation to an accuracy of 25 millimeters. Cooley, who has experience using satellites to study water levels in Arctic lakes, was interested in bringing the satellite’s precise measurement capacity to bear on lake levels worldwide.

Cooley says that ICESat-2’s laser altimeter has far greater resolution than instruments used to measure water levels in the past. That made it possible to gather a large, precise dataset that included small ponds and reservoirs.

“With older satellites, you have to average results over a large area, which limits observations to only the world’s largest lakes,” Cooley said. “ICESat has a small footprint, so we can get levels for small lakes that we couldn’t get close to before. That was important for understanding global water dynamics, since most lakes and reservoirs are pretty small.”

From October 2018 to July 2020, the satellite measured water levels in 227,386 bodies of water, ranging in size from the American Great Lakes to ponds with areas less than one tenth of a square mile. Each water body was observed at different times of year to track changes in water levels. The researchers cross-referenced the water bodies they observed with a database of reservoirs worldwide to identify which water bodies were human-controlled and which were natural.

While countries like the U.S. and Canada gauge reservoir levels and make that information publicly available, many countries don’t publish such data. And very few non-reservoir lakes and ponds are gauged at all. So there was no way to do this analysis without the precise satellite observations, the researchers said.

  Commandeering the water cycle

The study found that while natural lakes and ponds varied seasonally by an average of .22 meters, human-managed reservoirs varied by .86 meters. Added together, the much larger variation in reservoirs compared to natural lakes means that reservoirs account for 57% of the total variation. In some places, however, human influence was even stronger than that. For example, in arid regions like the Middle East, American West, India and Southern Africa, variability attributed to human control surges to 90% and above.

“Of all the volume changes in freshwater bodies around the planet — all the floods, droughts and snowmelt that push lake levels up and down — humans have commandeered almost 60% of that variability,” Smith said. “That’s a tremendous influence on the water cycle. In terms of human impact on the planet, this is right up there with impacts on land cover and atmospheric chemistry.”

As the first global quantification of human impacts on the water cycle, the results will provide a crucial baseline for future research on how the impacts affect ecosystems around the world, the researchers say.

In a separate study published recently in Geophysical Research Letters, the research team was able to use ICESat-2 data to shed light on how reservoir water is being used. The study showed that in places like the Middle East, reservoir levels tend to be lower in summer and higher in the winter. That suggests that water is being released in the dry season for irrigation and drinking water. In contrast, the trend in places like Scandinavia was the opposite. There, water is released in the winter to make hydroelectric power for heating.

“This was an exploratory analysis to see if we can use remote sensing to understand how reservoirs are being used at a global scale,” Ryan said.

Smith says he expects satellites to play an increasing role in study of the Earth’s water cycle. For the past few years, he has been working with NASA on the Surface Water and Ocean Topography mission, which will be dedicated entirely to this kind of research.

“I think within the next three years we are going to see an explosion of high-quality satellite hydrology data, and we’re going to have a much better idea of what’s going on with water all over the planet,” Smith said. “That will have implications for security, trans-boundary water agreements, forecasting crop futures and more. We’re right on the edge of a new understanding of our planet’s hydrology.”

The research was supported by the NASA Studies with ICESat-2 Program (80NSSC20K0963) and the NASA Surface Water and Ocean Topography mission (80NSSC20K1144S).

FOR MORE INFORMATION: Brown University

Transmission risk of COVID-19 from sewage spills into rivers can now be quickly quantified

Scientists have identified that the COVID-19 virus could be transmitted through faecal contaminated river water.

A team of researchers, including water quality, epidemiology, remote sensing and modelling experts, led by Dr Jamie Shutler at the University of Exeter, have developed a fast and simple way to assess the potential risk of water-borne transmission of the COVID-19 virus, posed by sewage spills into open and closed freshwater networks. 

The new study, published in the journal Environmental Science and Technology – Water, identifies the relative risk of viral transmission by sewerage spills, across 39 different counties. 

The study used information on the environment, a population’s infection rate, and water usage to calculate the potential potency of viral loads in the event of a sewerage spill. 

The research team believe the new study could provide fresh impetus in identifying new ways in which to prevent the spread of the virus amongst communities and the environment. 

Dr Jamie Shutler, lead author of the study and at the University of Exeter’s Penryn Campus in Cornwall said: “it’s important to identify and break all viable transmission routes if we want to stop any future outbreaks”. 

Airborne water droplets have previously been highlighted as the main route for transmission of the virus which causes COVID-19, but we know that other forms of transmission are likely to exist. 

Previous studies have shown that COVID-19 viral pathogens can be found in untreated wastewater, in concentrations consistent with population infection rates. While studies are still relatively early in relation to COVID-19, other human coronaviruses are documented to survive in wastewater, with colder water temperature likely to increase viral survival. 

Using this knowledge and existing methods, the research team identified how the transmission risk from water contaminated with sewage reduces over time. 

This issue is likely to be especially problematic in parts of the world with a large proportion of temporary settlements, such as shanty towns, favellas or refugee camps, which are less likely to have safe sanitisation systems. Or any densely populated region that has high infection rates that also suffers from a sewage spill. 

Modifying established pollution analysis methods, the team were able to estimate the viral concentration in rivers after a sewage spill. This meant they could calculate the relative transmission risk posed to humans by contaminated waterways for 39 countries.  

These methods, the team argue, provides a fast way to assess the transmission risk associated to sewage spills through the use of easily available population, infection rate and environmental data, allowing evidence based guidance following a spill. 

Dr Shutler added: “we hope that water companies or NGOs will use our simple spreadsheet calculator, that is freely available, to estimate the transmission risk after a spill. They can then use this information to advise the public.” 

 This research was partially funded by the European Union project Aquasense, which is focussing on novel methods to study and monitor water quality. 

The research resulted from a collaboration between the University of Exeter in Cornwall, the University of Glasgow, the Łukasiewicz-Institute of Electron Technology in Poland, and the University of Agriculture in Kraków, Poland. 

Journal Reference:

  1. Jamie D. Shutler, Krzysztof Zaraska, Thomas Holding, Monika Machnik, Kiranmai Uppuluri, Ian G. C. Ashton, Łukasz Migdał, Ravinder S. Dahiya. Rapid Assessment of SARS-CoV-2 Transmission Risk for Fecally Contaminated River WaterACS ES&T Water, 2021; DOI: 10.1021/acsestwater.0c00246

FOR MORE INFORMATION: https://www.exeter.ac.uk/news/research/title_845759_en.html

Visiting water bodies worth billions to economies

Europeans spend more than £700 billion (€800bn) a year on recreational visits to water bodies – but perceived poor water quality costs almost £90 billion (€100bn) in lost visits, a new study has found.

The new research – led by a European collaboration involving the University of Exeter and the University of Stirling – used data from 11,000 visits in 14 different countries to analyse the economic value of water bodies, such as rivers, lakes, waterfalls, beaches and seaside promenades.

The research team estimated that people spend an average of £35 (€40) travelling to and from these sites, with a typical family making 45 such trips each year.

The team also found that people were much less likely to visit sites if the perceived water quality fell, at a cost of well over €100 billion per year. The finding highlights the importance of maintaining and improving high bathing water quality standards.

Published in Science of the Total Environment, the team’s calculations indicate that, across Europe, total expenditure relating to trips to water-based settings is in excess of £700 billion annually.

Professor Tobias Börger, of the Berlin School of Economics and Law, used data collected as part of the European Union-funded BlueHealth project, which surveyed more than 18,000 people on their use of water bodies and their health and wellbeing. He explained: “The COVID-19 crisis has taught us all how important access to natural green and blue spaces is for people’s mental health and wellbeing. Our research highlights that it’s also critical for the economy to maintain high standards of water quality, as the pandemic crisis begins to ease.”

Following a Directive adopted by the European Commission, across the EU-member states, more than 15,000 coastal and almost 7,000 inland designated bathing water sites must now prominently display signs stating water quality over the past four years. Around 95 per cent of sites meet minimum quality standards and are considered safe for bathing, while 85 per cent are rated as having excellent water quality.

Professor Danny Campbell, from the University of Stirling, a co-author on the study, added: “While the study reveals that changes in water quality matter to people, we found that household income and educational attainment are not related to visiting water bodies. This shows that all parts of society can and do enjoy the benefits of such visits in terms of recreation, health and wellbeing.”

The findings fit well with a growing body of work looking at people’s experiences of inland and coastal waters and health across Europe. Co-author of the study, Dr Mathew White at the University of Exeter, said: “Blue spaces benefit people in a variety of ways. They encourage physical activity, they help de-stress and relax people, and they are important places for spending quality time with family and friends, all things which help people’s mental and physical health. This research finds that good water quality is key in encouraging people to take up these benefits.”

The team hopes their study will help planners and regulators justify the costs of building and maintaining the infrastructure needed to keep bathing water quality high.

Journal Reference:

  1. Tobias Börger, Danny Campbell, Mathew P. White, Lewis R. Elliott, Lora E. Fleming, Joanne K. Garrett, Caroline Hattam, Stephen Hynes, Tuija Lankia, Tim Taylor. The value of blue-space recreation and perceived water quality across Europe: A contingent behaviour studyScience of The Total Environment, 2021; 145597 DOI: 10.1016/j.scitotenv.2021.145597

FOR MORE INFORMATION: https://www.exeter.ac.uk/news/research/title_844637_en.html

Short-term climate modeling forecasts drought for Southeast US

Dried ground with mudcracks and grass growing around edges.

CHAMPAIGN, Ill. —Many climate models focus on scenarios decades into the future, making their outcomes seem unreliable and problematic for decision-making in the immediate future. In a proactive move, researchers are using short-term forecasts to stress the urgency of drought risk in the United States and inform policymakers’ actions now.

A new study led by University of Illinois Urbana-Champaign civil and environmental engineering professor Ximing Cai examines how drought propagates through climate, hydrological, ecological and social systems throughout different U.S. regions. The results are published in the journal Geophysical Research Letters.

“The same amount of precipitation, or the lack of thereof, in one region could have very different impacts on the hydrologic cycle, streamflow and water storage in another region,” Cai said. “The impacts of droughts are closely related to climate and environmental characteristics, and both together can have very different impacts on human water usage and supply.”

For example, the team predicted that lack of rainfall in the Southeastern region poses a greater risk than it does in the Southwest. The Southwest has a relatively large water-storage capacity, unlike the Southeast, which has a limited storage capacity and faces increased demand. Their prediction proved accurate, according to their models.

Cai and co-author Tushar Apurv compiled previously collected meteorologic, soil and hydrologic data from 30 regions around the U.S. from the past few decades. Using this data, they calculated a ratio representing how severe the hydrologic droughts are relative to meteorological droughts in these regions. This ratio helped them determine where water availability and water supply deficits have been occurring over time.

The study reports that precipitation deficits have decreased in Northern parts of the U.S. and increased in the Southwestern and Southeastern regions due to climate change, the researchers said. As a result, the Southwest has experienced severe drought effects on ecosystems in the area in recent years, which is likely to continue into the next decade – with severe drought conditions already in place since August.

However, according to the study, the forecasted Southeastern drought could lead to a very different outcome than the Southwestern drought.

“If this trend of increasing drought severity persists, as also predicted by other studies, the Southeast could be at very high risk for extreme drought, which might not have been realized in the past,” Cai said. “This will expose their water-supply infrastructure to stress beyond its design limit.”

In other words, there is a risk that the Southeast may not be as well prepared to handle near-future drought as the Southwest, which appears to have the situation better controlled, Cai said.

The researchers plan to explore more detailed studies on some of the watersheds to help uncover solutions, but they are more eager to flag the attention of policymakers right now.

“We think this study provides the scientific support needed to punctuate the immediate threat posed by drought,” Cai said. “We see our results as an incentive for decision-makers to bring drought mitigation to the forefront of environmental and water-management policy.”

Journal Reference:

  1. Tushar Apurv, Ximing Cai. Regional Drought Risk in the Contiguous United StatesGeophysical Research Letters, 2021; 48 (5) DOI: 10.1029/2020GL092200

FOR MORE INFORMATION: University of Illinois at Urbana-Champaign, News Bureau

Climate and Water webinar series

Starting in February, the UNDP-SIWI Water Governance Facility, Global Water Partnership, Alliance for Global Water Adaptation, and Cap-Net will deliver a 3-part series on water and climate.

The webinars will explore the role water should have in the Nationally Determined Contributions (NDC) under the Paris Agreement.

18 February: Interactions between water and different sectors. The first webinar we will discuss the importance of ensuring that water interactions are considered in their NDCs, as countries adjust development paths as a result of Covid-19 impact on country finances, intersectoral linkages, observations on differences between first and enhanced NDCs. It will introduce a practical tool for identifying climate and water inter-linkages.

25 February: From Commitments to Implementation. In the second webinar the conversation aims to share experiences in preparing documents that include climate change related activities, as well as their lessons from addressing commitments found in the first round of NDC’s.

4 March: Climate Finance – Exploring Options for Funding Water & Climate. The third webinar aims to build on the learnings of the first webinar that introduced the three main global climate finance mechanisms and their modalities. In this session the emphasis will be on the practicalities of securing finance, obtaining accreditation, and building good investment cases by using examples from successful entities.

  • Registration and useful resources for the webinars are available here.

FOR MORE INFORMATION: https://www.unwater.org/climate-and-water-webinar-series/

Positive reinforcements help algorithm forecast underground natural reserves

artist's rendering of a person's handing next to a computer screen showing an algorithm

Texas A&M University researchers have designed a reinforcement-based algorithm that automates the process of predicting the properties of the underground environment, facilitating the accurate forecasting of oil and gas reserves.

Within the Earth’s crust, layers of rock hold bountiful reservoirs of groundwater, oil and natural gas. Now, using machine learning, researchers at Texas A&M University have developed an algorithm that automates the process of determining key features of the Earth’s subterranean environment. They said this research might help with accurate forecasting of our natural reserves.

Specifically, the researchers’ algorithm is designed on the principle of reinforcement or reward learning. Here, the computer algorithm converges on the correct description of the underground environment based on rewards it accrues for making correct predictions of the pressure and flow expected from boreholes.

“Subsurface systems that are typically a mile below our feet are completely opaque. At that depth we cannot see anything and have to use instruments to measure quantities, like pressure and rates of flow,” said Siddharth Misra, associate professor in the Harold Vance Department of Petroleum Engineering and the Department of Geology and Geophysics. “Although my current study is a first step, my goal is to have a completely automated way of using that information to accurately characterize the properties of the subsurface.”

The algorithm is described in the December issue of the journal Applied Energy.

Simulating the geology of the underground environment can greatly facilitate forecasting of oil and gas reserves, predicting groundwater systems and anticipating seismic hazards. Depending on the intended application, boreholes serve as exit sites for oil, gas and water or entry sites for excess atmospheric carbon dioxide that need to be trapped underground.

Along the length of the boreholes, drilling operators can ascertain the pressures and flow rates of liquids or gas by placing sensors. Conventionally, these sensor measurements are plugged into elaborate mathematical formulations, or reservoir models, that predict the properties of the subsurface such as the porosity and permeability of rocks.

But reservoir models are mathematically cumbersome, require extensive human intervention, and at times, even give a flawed picture of the underground geology. Misra said there has been an ongoing effort to construct algorithms that are free from human involvement yet accurate.

For their study, Misra and his team chose a type of machine-learning algorithm based on the concept of reinforcement learning. Simply put, the software learns to make a series of decisions based on feedback from its computational environment.

“Imagine a bird in a cage. The bird will interact with the boundaries of the cage where it can sit or swing or where there is food and water. It keeps getting feedback from its environment, which helps it decide which places in the cage it would rather be at a given time,” Misra said. “Algorithms based on reinforcement learning are based on a similar idea. They too interact with an environment, but it’s a computational environment, to reach a decision or a solution to a given problem.”

So, these algorithms are rewarded for favorable predictions and are penalized for unfavorable ones. Over time, reinforcement-based algorithms arrive at the correct solution by maximizing their accrued reward.

Another technical advantage of reinforcement-based algorithms is that they do not make any presuppositions about the pattern of data. For example, Misra’s algorithm does not assume that the pressure measured at a certain time and depth is related to what the pressure was at the same depth in the past. This property makes his algorithm less biased, thereby reducing the chances of error at predicting the subterranean environment.

When initiated, Misra’s algorithm begins by randomly guessing a value for porosity and permeability of the rocks constituting the subsurface. Based on these values, the algorithm calculates a flow rate and pressure that it expects from a borehole. If these values do not match the actual values obtained from field measurements, also known as historical data, the algorithm is penalized. Consequently, it is forced to correct its next guess for the porosity and permeability. However, if its guesses were somewhat correct, the algorithm is rewarded and makes further guesses along that direction.

The researchers found that within 10 iterations of reinforcement learning the algorithm was able to correctly and very quickly predict the properties of simple subsurface scenarios.

Misra noted that although the subsurface simulated in their study was simplistic, their work is still a proof of concept that reinforcement algorithms can be used successfully in automated reservoir-property predictions, also referred as automated history matching.

“A subsurface system can have 10 or 20 boreholes spread over a two- to five-mile radius. If we understand the subsurface clearly, we can plan and predict a lot of things in advance, for example, we would be able to anticipate subsurface environments if we go a bit deeper or the flow rate of gas at that depth,” Misra said. “In this study, we have turned history matching into a sequential decision-making problem, which has the potential to reduce engineers’ efforts, mitigate human bias and remove the need of large sets of labeled training data.”

He said future work will focus on simulating more complex reservoirs and improving the computational efficiency of the algorithm.

Hao Li of the University of Oklahoma was a contributor to this work. This research is funded by the United States Department of Energy.

FOR MORE INFORMATION: Texas A&M University

For Selenium in Rivers, Timing Matters

The Lower Gunnison River in Colorado, where scientists are testing for the substance selenium.
The sampling team on the main stem of the Lower Gunnison River, Colorado at Dominguez-Escalante Canyon. (Photo courtesy of the USGS).

elenium contamination of freshwater ecosystems is an ongoing environmental health problem around the world. A naturally occurring trace element, selenium levels are high in some geologic formations like sedimentary shales that form much of the bedrock in the Western United States. Soils derived from this bedrock, and weathering of shale outcrops, can contribute high levels of selenium to surrounding watersheds.

New research out this week in Environmental Science & Technology from UConn Assistant Professor of Natural Resources and the Environment Jessica Brandt with Travis Schmidt and colleagues at the United States Geological Survey (USGS) investigates some of the complexities of selenium and how it moves through the ecosystem  during runoff events and as a result of seasonal irrigation of selenium-enriched soils.

The research focused on the Lower Gunnison River Basin in Colorado, an area impacted by selenium-enriched bedrock known as the Upper Cretacous Mancos Shale, and designated critical habitat for the endangered razorback sucker (Xyrauchen texanus) and Colorado pikeminnow (Ptychocheilus lucius). Between June 2015 and October 2016, the research team sampled water and wildlife across six sampling trips and along 60 river miles between Austin and Grand Junction, CO.

Researchers processing water samples on the banks of the Gunnison River in Colorado, looking for traces of selenium.
The field crew processing samples along the Gunnison River, Colorado. (Phot courtesy of Travis Schmidt, USGS).

Brandt explains that the focus of the study was on the timing of selenium movement through the riverine food web. Particulate matter including algae take up selenium from the water at the base of the food web. Invertebrates and some small fish feed directly on the particulate material, and bigger fish then eat the invertebrates and smaller fish.

“Selenium is an essential micronutrient acquired through the diet, but excess exposure threatens the health of egg-laying animals, including fish and aquatic birds. On top of that, the timing of exposure matters. For instance, too much selenium as an embryo is particularly concerning because it impairs development and reduces the chances of hatching and survival to adult life stages. We wanted to know when, over the course of the year, are fish exposed to the highest concentrations of selenium in the food web? Do those periods coincide with windows of reproduction and early-life development? Are they aligned with periods of increased selenium mobilization to the river?”

For the most part, the answers to those questions were yes. Selenium concentrations reached their highest concentrations in fish prey in April and August 2016 when selenium is pulsed into the river from snowmelt and during irrigation of agricultural fields. By modeling fish concentrations from selenium levels lower in the food web, Brandt and collaborators predicted that whole-body selenium levels were highest during the spring and summer. During these periods, eggs are maturing in adult fish prior to spawning and young of the year fish are experiencing stages of development that are susceptible to high selenium exposures. (See sidebar)

Brandt explains the study is important because of its focus on a fast-flowing water system. Most case studies of waterbodies contaminated with selenium are about lakes and reservoirs where selenium reaches high concentrations in fish and birds after moving through the sediment-detrital pathway. Because the water moves more slowly in these systems, selenium has more opportunity to accumulate at the base of the food web. In rivers, on the other hand, it is thought that most of the selenium mobilized during periods of high flow will be flushed downstream before it can accumulate locally,

“We observed that green algae can take up selenium pretty rapidly during periods of high mobilization, likely from the water column directly. One hypothesis going forward is that algal uptake pathways for selenium entry to aquatic food webs, rather than sediment-detrital pathways, might dominate in rivers and streams. This study indicates that we need to be spending more time thinking about selenium risks in rivers.”

Brandt says this research has implications for the management of selenium sampling in rivers. For example, fish sampling typically happens in the fall when the results of this study suggest that selenium concentrations in fish might be at their lowest. Even still, the measured concentrations were high,

“We sampled speckled dace and roundtail chub in October 2015 and 2016,” says Brandt, “Whole-body selenium concentrations in more than 90% of these fish were well above four parts per million, which is a threshold supported by research showing adverse health effects like reduced growth and survival. Because the river is habitat for native endangered species, maintaining fish health is a priority.”

Selenium levels in the Lower Gunnison River Basin have been a concern for several decades now and Brandt explains that ongoing remediation efforts in the Gunnison have reduced levels by 43% since 1986. But perhaps more can be done to further bolster these efforts

“Do we need to be approaching selenium assessments in impaired rivers in a different way? Well, we see from this work that selenium concentrations in the food web are high even with drops in water concentrations over the last thirty plus years. This highlights that the food web is the primary driver of selenium exposure and potential toxicity risk.  More frequent monitoring of food web selenium in this system will give us the best information about how to manage selenium in order to meet fish conservation goals.”

FOR MORE INFORMATION: University of Connecticut

‘No Other Option’: Deadly India Floods Bare Conflicts From Hydropower Boom

Reuters
Kundan Singh, 48, poses for a picture near his home after a flash flood swept down a mountain valley destroying dams and bridges, in Raini village in the northern state of Uttarakhand, India, February 11, 2021. Picture taken February 11, 2021. REUTERS/Anushree Fadnavis

RAINI, India (Reuters) – Growing up in a remote tribal village high in the Indian Himalayas, Kundan Singh loved to play on a field by the sparkling Rishiganga river.

The 48-year-old recalls afternoons there competing in sports tournaments, surrounded by forests of pine.

Fifteen years ago, bulldozers descended on Raini village to build a dam, part of a push by India to increase hydroelectric power. The field was lost, and villagers have been in conflict with the Rishiganga Hydropower Project ever since.

The dam was swept away two weeks ago in a flash flood that also smashed bridges and another hydroelectric power station in the Dhauliganga river valley of Uttarakhand state, leaving over 200 feared dead.

Whatever the role of climate change, which is rapidly heating the world’s highest mountains, experts say rampant construction is adding to the burden weighing on rural communities across the Himalayas.

This building boom is creating conflict across the region, as shown by interviews with nearly two dozen Raini villagers, legal and technical documents, satellite imagery and photographs, and correspondence with local officials, some of it not previously reported.

“We wrote letters, we protested, we went to court, we did everything,” Singh said. “But no one heard us.”

JOBS DIDN’T COME

The 150 villagers are members of the Bhutia tribe of historically nomadic shepherds from Tibet, some of whom settled in India after a 1962 war with China closed the border.

Granted protected status with government quotas for jobs and education, many nonetheless live in poverty in the mountainous state, labouring on roads and construction sites, weaving woollen rugs and growing potatoes and pulses on small plots around a bend in the river.

Villagers were initially enthusiastic at the prospect of a power plant that promised jobs, according to court documents, the project’s impact assessment and minutes of a 2006 meeting between village leaders and representatives of the dam.

But the jobs did not come, Singh and other locals said. Those who managed to find work on the dam clashed with the owners over unpaid wages and alleged construction violations, according to court documents.

A paint company from Punjab controlled the dam during initial construction. It has not filed accounts since 2015, and its current directors could not be reached for comment. The project entered bankruptcy before being bought by the Kundan Group in 2018, and finally started operations last year. Executives at the conglomerate did not respond to calls and emails seeking comment.

As India seeks to nearly double its hydropower capacity by 2030, construction of dams in the region is increasingly leading to disagreements between plant owners and locals, said Himanshu Thakkar, coordinator of the South Asia Network on Dams, Rivers and People, which has studied the conflicts.

“It happens with many projects,” he said. “People want to resist and oppose, but project developers… will always make promises of employment and development.”

In the Alaknanda basin, a cluster of streams that feeds the Ganges river – worshipped as a god by many Hindus – six hydroelectric dams have been constructed, according to Thakkar’s nonprofit. Eight more, including the Tapovan dam that was severely damaged in the Feb. 7 floods, are under construction, while a further 24 have been proposed.

A spokeswoman for India’s power ministry said the country has strict measures in place regarding the planning of hydropower projects and the rights of local people are always considered.

MUDDY BANKNOTES, RUBBLE

During the dam’s construction, blasts from explosives were frequent, according to interviews with about 20 residents and court documents.

The use of explosives in construction in the region was criticised after devastating floods in Uttarakhand in 2013, dubbed a “Himalayan tsunami” that claimed some 6,000 lives.

In 2019, Singh and his brother took a two-day bus journey to meet with lawyer Abhijay Negi, who recalled them arriving with a bundle of muddy banknotes collected from other residents as payment.

“Please help us save our village,” Singh told him.

Negi helped the men file a case against the Kundan Group unit operating the dam, alleging construction had left behind loose rubble and rocks, according to photographs and diagrams submitted as evidence.

Uttarakhand’s top court ruled there was evidence of “substantial damage” to the area that suggested explosives were being used for illegal mining, though it did not rule on when the damage occurred. The court ordered a local investigation, but it is not clear if this has happened and officials involved could not be reached.

High up on the mountain, almost all the Raini residents survived the floods. But Singh said the disaster has left many dreaming of escape.

“Many want to leave, but I will stay because I have no other option,” he said. “I will stay because of poverty.”

FOR MORE INFORMATION: https://www.usnews.com/news/world/articles/2021-02-22/no-other-option-deadly-india-floods-bare-conflicts-from-hydropower-boom