Climate Change Conservation Water

2023 March World Water Day

In honour of World Water Day, which is today, I thought we’d review some recent articles about that most essential element for gardeners.

Major water-related events in 2022. Credit: Global Water Monitor 2022 Summary Report

Global water & climate change

A new report shows alarming changes in the entire global water cycle. Behind the changes expected under climate modelling scenarios, are troubling signs the entire global water cycle is changing. A research team led by Albert Van Dijk from Australian National University, analyses observations from more than 40, merged with data from thousands of weather and water monitoring stations on the ground. Drawing on those many terabytes of data, they paint a full picture of the water cycle over a year for the entire globe, as well as for individual countries. The findings are contained in a recently released report. The key conclusion? Earth’s water cycle is clearly changing. Globally, the air is getting hotter and drier, which means droughts and risky fire conditions are developing faster and more frequently.

A satellite image of Siberia Lena delta that flows in the Arctic Ocean. Credit: NASA

Why rivers matter for the global carbon cycle

Writing from École Polytechnique Federale de Lausanne, Rebecca Mosimann notes that, until recently, our understanding of the global carbon cycle was largely limited to the world’s oceans and terrestrial ecosystems. Tom Battin, who heads EPFL’s River Ecosystems Laboratory (RIVER), has now shed new light on the key role that river networks play in our changing world. These findings are outlined in a review article commissioned by and published in Nature. Writing with a dozen experts and using the most recent data, this work demonstrates the critical importance of river ecosystems for global carbon fluxes—integrating land, atmosphere and the oceans.

Image courtesy of Farooq Khan on Pexels.

Pollution & Water Treatment

When I was running the Canadian Environment Industry Association* in the late 1990s, one persistent problem with water treatment was removing pharmaceutical residues from drinking water. This has remained an issue for some classes of drugs but he last couple of decades have seen impressive advances. Prof. Dr. Juergen Kolb, an expert in environmental technologies at the Leibniz Institute for Plasma Science and Technology (INP), explains the current state of research. “We combine classical physical processes for wastewater purification with new technologies such as ultrasound, pulsed electric fields and plasma technology. This allows us to break down chemical compounds such as drug residues but also other man-made contaminants and convert them into harmless substances.” These methods have already proven their potential in various INP research projects. Currently, the approaches are being transferred to practice-relevant environments. “Our approach is currently mobile plants that can be used in hospitals, for example, where water contamination with pharmaceutical residues is particularly high. Particularly in view of the increasing number of antibiotic-resistant microorganisms, we see an acute need for action here,” Kolb adds. The technologies are also suitable for municipal sewage treatment plants as a fourth purification stage. The full article is titled: Innovative technologies to remove pharmaceutical residues from wastewater.

(CEIA no longer exists, but its Ontario provincial counterpart does. See Ontario Environment Industry Association.)

Image of a stormwater pond from the website of Kanata-South councillor Allan Hubley.

Living alongside the Ottawa River, stormwater management is a neighbourhood issue. Following flooding events in 2017 and 2019, the National Capital Commission has been busy rebuilding the retaining wall between us and the river. Sadly “green infrastructure” is not part of their engineering solution, which started instead with clear-cutting almost every tree along the river side of the wall.

Trees felled by NCC for “flood control” along the Ottawa River. Photo courtesy of Andrew Scott.

Green stormwater infrastructure

Writing in Phys.Org, Leslie Lee of Texas A&M University discusses green stormwater solutions to the stormwater runoff issues caused by growing populations, more hard surfaces from expanding cities, and climate change-driven extreme weather events. To help cities grow their stormwater management strategy portfolios, Texas A&M AgriLife Research and AgriLife Extension staff at the center in Dallas are working on many stormwater-related projects. The idea behind green stormwater infrastructure (GSI) is to take downstream effects of water management into consideration and to promote more rainwater to infiltrate the soil and replenish aquifers, rather than simply running off into the nearest body of surface water.

Although many U.S. cities have been slow to adopt, a research review published in WIREs Water proposes strategies for municipalities and decision-makers to overcome barriers and use green stormwater infrastructure for long-term benefits.

Image from New Phytologist, Volume: 238, Issue: 1, Pages: 33-54, First published: 23 January 2023, DOI: (10.1111/nph.18762).

How plants are inspiring new ways to extract value from wastewater

Scientists from The Australian National University (ANU) are drawing inspiration from plants to develop new techniques to separate and extract valuable minerals, metals and nutrients from resource-rich wastewater. The ANU researchers are adapting plant ‘membrane separation mechanisms’ so they can be embedded in new wastewater recycling technologies. This approach offers a sustainable solution to help manage the resources required for the world’s food, energy and water security by providing a way to harvest, recycle and reuse valuable metal, mineral and nutrient resources from liquid wastes. The research is published in New Phytologist.

Rain barrel at the side of Rebecca’s home. Photo by Jon Last.

Potential Contaminants in Residential Rain Barrel Water

In a new paper on ResearchGate, Linda Chalker Scott notes residential gardeners often use rain barrels to collect rainwater from roofs as a supplement to summer irrigation. Rainwater is a natural and unchlorinated water source for aquatic plants and animals. However, rooftop runoff can be contaminated by chemical and biological pollutants from atmospheric deposition, bird droppings, and the roofing material itself. This publication examines the state of knowledge on residential rain barrel water safety in North America over the last 20 years. Among the simple, research-based practices gardeners can use to take advantage of collected rainwater, while also reducing the risks of contamination exposure are:

  • Knowing your local pollution issues
  • Avoid collecting rainwater: when air quality is low (smoggy, temperature inversions, low wind speeds); if you have recently used a moss removal product on the roof; or if pesticides have been recently applied nearby.
  • Use good garden hygiene, including: keeping your barrels well sealed, and using mosquito netting on the top of them; not drinking rainwater or touching your wet hands to your mouth or eyes; washing your hands after handling rainwater; and cleaning the barrels regularly.
  • Wash garden produce before eating it.
  • Install a diverter for the first flush of rain to capture the worst of the contaminants.

Closer to Home

Photo from Ontario Parks website.

Ontario wetlands under threat

Angelica Marie Sanchez from University of Waterloo, quotes Dr. Rebecca Rooney, a wetland ecologist and professor in the Department of Biology. “Wetlands are a portfolio of ecosystem services: including flood prevention, breaking down pesticides, storing large amounts of carbon, and provide habitat for more than 32% of Ontario species at risk who rely on these wetlands to mitigate climate change.” Canada is home to 25% of the world’s wetlands. But according to Rooney, Canada has lost more than 60% of its wetlands over the years. In agricultural areas, wetlands have been drained to make space for farming. While in urban and suburban areas, Canada has lost the majority of its wetlands due to them being drained for housing development. Stormwater ponds are engineered solutions created to effectively replace wetlands across Ontario. However, these ponds only address some of the problems including flood prevention, but they need to provide the full portfolio of ecosystem services that wetlands provide.

While the More Homes Built Faster Act, formerly known as Bill 23, aims to address the housing crisis in Ontario, it will be devastating for the province’s wetlands. The proposals posted to the Environmental Registry of Ontario included changes to the Ontario Wetland Evaluation System, which is the instrument the provinces uses to determine whether a wetland gets classified as provincially significant. “… Unfortunately, the changes that are being proposed to the Ontario wetland evaluation system will dramatically undermine its efficacy and endanger wetlands across Ontario,” says Rooney. “There is a huge amount of scientific evidence that connects these pockets of wetlands into a whole integrated network,” says Rooney. “If you start chipping away at the wetlands and you destroy one piece of it, the whole network is going to suffer under the current proposals.”

Rooney encourages people to act by learning more about the act and its impact on Canada’s wetlands.

Aerial view of the Dezadeash River, Yukon, meandering through vegetated permafrost. (Photo credit: Alessandro Ielpi). Image from Stanford Earth Matters magazine.

Arctic river channels changing

A team of international researchers monitoring the impact of climate change on large rivers in Arctic Canada and Alaska determined that, as the region is sharply warming up, its rivers are not moving as scientists have expected. Dr. Alessandro Ielpi, an Assistant Professor with UBC Okanagan’s Irving K. Barber Faculty of Science, is a landscape scientist and lead author of a paper published in Nature Climate Change. Dr. Ielpi says the assumption of faster river channel migration owing to climate change has dominated the scientific community for decades. “But the assumption had never been verified against field observations,” he adds. To test this assumption, Dr. Ielpi and his team analyzed a collection of time-lapsed satellite images—stretching back more than 50 years. They compared more than a thousand kilometers of riverbanks from 10 Arctic rivers. “We found that large sinuous rivers with various degrees of permafrost distribution in their floodplains and catchments, display instead a peculiar range in migration rates,” says Dr. Ielpi. “Surprisingly, these rivers migrate at slower rates under warming temperatures.” One reason why is that warmer temperatures mean more vegetation, which helps to stabilize river banks.

Good News Stories

In 2004, frontyard lawns were prohibited for new subdivisions in the Las Vegas area. Above, the suburban community of Mountain’s Edge. (Brian van der Brug / Los Angeles Times)

How Las Vegas declared war on thirsty grass

Writing in the LA Times, Molly Hennessy-Fiske and Ian James report on how Las Vegas has emerged as a leader in water conservation, and some of its initiatives have spread to other cities and states that rely on the shrinking river. Its drive to get rid of grass in particular could reshape the look of landscapes in public and private spaces throughout the Southwest. In 2002, as the reservoir level dropped, the Southern Nevada Water Authority used more than its allocation of Colorado River water. At that point, the agency’s leaders decided to pivot quickly toward conservation. Cash rebates to encouraged residents to rip out lawns and put in landscaping with desert plants. In 2003, the Las Vegas area’s consumption of Colorado River water shrank more than 16%. Those conservation gains continued as the area’s water suppliers strengthened their rules, targeting grass. As the article details, not everyone is happy with the restrictions, but they are helping to conserve valuable water resources.

Photo by Johannes Plenio on Pexels.

Drought detection on the cheap

Meanwhile researchers at University of Barcelona recently published a study in the journal Trends in Plant Science that presents a set of techniques that enable researchers to detect and monitor drought stress in plants in a cheap, easy and quick way. The study responds to the need to establish effective and low-cost protocols to easily detect and study how droughts affect plants. Specifically, the authors present a battery of very accessible techniques that can be applied with basic laboratory equipment: precision balance, microscope, centrifuge, spectrophotometer, oven, camera and computer.

Credit: Pixabay/CC0 Public Domain

In other good news Everglades restoration moves closer to reality with a crucial groundbreaking. Elsewhere Albania’s ‘wild river’ now a national park.


2023 January Water Watch

Rain barrel used to irrigate a side raised bed. Photo by R. Last.

If more houses had water barrels, it could help with drought, flooding and water pollution

Earlier in 2022, southern England experienced its driest July on record. The drought affected many parts of the UK and grew so acute that Thames Water’s hosepipe ban will remain in force into 2023. But rainfall in August 2022 was heavy. The volume of rain caused outdated drainage and sewerage systems to overflow, degrading the quality of many of the UK’s rivers. Extreme weather patterns such as these are set to dominate our future. Research by Community Action for Water suggests that collecting rainwater in water butts may offer a solution to these problems. This cheap, small-scale intervention could help protect households against water risks while engaging those involved with water issues. Unfortunately, the government tends to ignore this scale of intervention. Water management in England is largely isolated to large infrastructure projects. Reservoirs are built to withstand drought and larger sewers are seen as the solution to flooding and water pollution. These approaches are costly (Central London’s new sewer will cost £4.3 billion), can damage the environment, and they fail to engage the public. There are other ways to manage the UK’s water better. The roof area of an average terraced house in the UK (30m²) receives 19,000–55,000 litres of rain each year. Our modelling suggests that a significant proportion of household water consumption could be met by collecting this water. Averaged across the UK, we found that a 210-litre rain tank – equivalent to a small bath – could supply 15% of a household’s total annual water consumption. But this will be subject to clear geographic and seasonal variation.

Clip art illustration of a watering can pouring water on a seedling in a pot. Shutterstock stock illustration ID: 85170565.

Water for Food Systems and Nutrition

Access to sufficient and clean freshwater is essential for all life. Water is also essential for the functioning of food systems: as a key input into food production, but also in processing and preparation, and as a food itself. Water scarcity and pollution are growing, affecting poorer populations most, and particularly food producers. Malnutrition levels are also on the rise, and this is closely linked to water scarcity. Achieving Sustainable Development Goals 2 (End hunger, achieve food security and improved nutrition and promote sustainable agriculture) and 6 (Ensure availability and sustainable management of water and sanitation for all) are co-dependent. Solutions for jointly improving food systems and water security outcomes include:

  1. Strengthening efforts to retain water-based ecosystems and their functions;
  2. Improving agricultural water management for better diets for all;
  3. Reducing water and food losses beyond the farmgate;
  4. Coordinating water with nutrition and health interventions;
  5. Increasing the environmental sustainability of food systems;
  6. Explicitly addressing social inequities in water-nutrition linkages; and
  7. Improving data quality and monitoring for water-food system linkages, drawing on innovations in information and communications technology (ICT).

Climate change and other environmental and societal changes make the implementation and scaling of solutions more urgent than ever.

Stock image on Pexels.

Optimising the water we eat—rethinking policy to enhance productive and sustainable use of water in agri-food systems across scales

Sustainable and resilient food systems depend on sustainable and resilient water management. Resilience is characterised by overlapping decision spaces and scales and interdependencies among water users and competing sectors. Increasing water scarcity, due to climate change and other environmental and societal changes, makes putting caps on the consumption of water resources indispensable. Implementation requires an understanding of different domains, actors, and their objectives, and drivers and barriers to transformational change. We suggest a scale-specific approach, in which agricultural water use is embedded in a larger systems approach (including natural and human systems). This approach is the basis for policy coherence and the design of effective incentive schemes to change agricultural water use behaviour and, therefore, optimise the water we eat.

Credit: Pixabay

Study sheds light on how PFAS ‘forever chemicals’ travel in groundwater

A large family of chemicals used for decades to improve our lives—from nonstick cooking pans to waterproof clothing—are now known as “forever chemicals” because they do not easily break down in the environment and pose potential health risks as they build up in our bodies. A new study may improve our understanding of how these chemicals move in the groundwater, according to a team of scientists. “These chemicals, called PFAS (per-and polyfluoroalkyl substances), are extremely useful, so they have been used everywhere,” said Kalle Jahn, a researcher at the United States Geological Survey, who conducted this work as a doctoral candidate at Penn State. “Unfortunately, at the smallest molecular level, they just don’t break down further in the natural environment. If they get released, they just hang around and can bioaccumulate in fish and other animals and eventually in us.” The scientists studied one such chemical, perfluorooctanesulfonic acid (PFOS), that made its way into groundwater near a former firefighter training center in Center County, Pennsylvania. PFOS is a common element in firefighting foams, and was used for decades at the fire training site. The chemical was not regulated at the time. PFOS molecules are hydrophobic and will attach to organic carbon, and variations in the organic carbon in the bedrock aquifer may influence concentrations of the chemical in groundwater, the scientists reported in the journal Groundwater. “Kalle’s work highlights an important consideration for modeling the groundwater transport of PFOS and similar compounds,” said Katherine Freeman, Evan Pugh University Professor of Geosciences and Jahn’s adviser at Penn State, who is a co-author on the paper. The article goes on to detail how the scientists detected two peaks in concentration of the PFOS plume, and what that means for ongoing water remediation. (See also: PFAS: you can’t smell, see or taste these chemicals, but they are everywhere—and they’re highly toxic to humans)

Sustainable Living Water

Green Stormwater Controls

Image courtesy of City of Toronto Green Streets Technical Guidelines.

Green stormwater control measures clean up urban streams: Catching urban runoff in raingardens and rainwater capture tanks improves the water quality of nearby streams and rivers and lowers water temperatures that have risen in the region due to climate change and the urban heat island effect, according to a new report spanning two decades in the greater Melbourne metropolitan area of Australia. When natural landscapes are replaced with urban infrastructure environments, the temperature of an area also increases, a phenomenon known as the urban heat island effect. As water runs through urban areas with impervious surfaces, it picks up pollutants and heat before discharging into waterways. The compound effects of urban expansion and climate change in the study region have increased the water temperature of nearby streams by as much as 5°C (9°F). Raingardens and rainwater tanks were able to restore degraded streams by filtering and cooling runoff before it entered the waterway, according to the study in Water Resources Research. Green stormwater infrastructure reduced the steams’ peak summer temperatures by about 5°C (9°F), effectively counteracting the regional warming. These catchment systems also filtered runoff from human activities, such as car washing, spilled gasoline, sewage, fertilization and irrigation, and prevented excess nutrients from entering the stream ecosystems. The study, one of the longest and largest to be completed on green stormwater control measures, found that raingardens and rainwater capture tanks were effective at reducing water temperatures and pollution in nearby streams at least 90% of the year. “In areas where we had green infrastructure systems in place, we saw significant water quality improvements,” said Christopher Walsh, an ecosystem scientist at the University of Melbourne and lead author of the study.


Rewilding Rivers

Credit: Bobjgalindo, CC BY-SA 4.0 , via Wikimedia Commons

In ‘momentous’ act, regulators approve demolition of four Klamath River dams: In a milestone decision, federal regulators on Thursday signed off on plans to demolish four aging dams along the Klamath River, paving the way for hundreds of miles of native fish habitat along the California-Oregon border to flow freely for the first time in more than a century. The Federal Energy Regulatory Commission’s decision will see licenses of the four dams transferred from the PacifiCorp energy company—a subsidiary of Warren Buffet’s Berkshire Hathaway—to the Klamath River Renewal Corporation, a nonprofit entity created to oversee the dam removal, and to the states of California and Oregon. The vote marks the final major hurdle for what will be the largest dam removal project in the nation’s history, officials said. The $500-million demolition has been championed by environmental organizations, commercial fishing groups and tribes who spent 20 years fighting for the river’s restoration.

Genetics, Breeding, Growth Water

Hydro Power Plants

From the soil to the sky: Researchers quantify the amount of energy that plants use to lift water on a global scale: Every day, about one quadrillion gallons of water are silently pumped from the ground to the treetops. Earth’s plant life accomplishes this staggering feat using only sunlight. It takes energy to lift all this liquid, but just how much was an open question until this year.

Researchers at UC Santa Barbara have now calculated the tremendous amount of power used by plants to move water through their xylem from the soil to their leaves. They found that on average, it was an additional 14% of the energy the plants harvested through photosynthesis. On a global scale, this is comparable to the production of all of humanity’s hydropower. Their study, published in the Journal of Geophysical Research: Biogeosciences, is the first to estimate how much energy goes into lifting water up to plant canopies, both for individual plants and worldwide. “It takes power to move water up through the xylem of the tree. It takes energy. We’re quantifying how much energy that is,” said first author Gregory Quetin, a postdoctoral researcher in the Department of Geography.

This energy is in addition to what a plant produces via photosynthesis. “It’s energy that’s being harvested passively from the environment, just through the tree’s structure.” The team combined a global database of plant conductance with mathematical models of sap ascent to estimate how much power the world’s plant life devotes to pumping water. They found that the Earth’s forests consume around 9.4 petawatt-hours per year. That’s on par with global hydropower production, they quickly point out.

Climate Change Water

Vanishing Lakes

Arctic lakes are vanishing in surprise climate finding: The Arctic is no stranger to loss. As the region warms nearly four times faster than the rest of the world, glaciers collapse, wildlife suffers and habitats continue to disappear at a record pace. Now, a new threat has become apparent: Arctic lakes are drying up, according to research published in the journal Nature Climate Change.

The study, led by University of Florida Department of Biology postdoctoral researcher Elizabeth Webb, flashes a new warning light on the global climate dashboard. Webb’s research reveals that over the past 20 years, Arctic lakes have shrunk or dried completely across the pan-Arctic, a region spanning the northern parts of Canada, Russia, Greenland, Scandinavia and Alaska. The findings offer clues about why the mass drying is happening and how the loss can be slowed. The vanishing lakes act as cornerstones of the Arctic ecosystem. They provide a critical source of fresh water for local Indigenous communities and industries. Threatened and endangered species, including migratory birds and aquatic creatures, also rely on the lake habitats for survival.

The lake decline comes as a surprise. Scientists had predicted that climate change would initially expand lakes across the tundra, due to land surface changes resulting from melting ground ice, with eventual drying in the mid-21st or 22nd century. Instead, it appears that thawing permafrost, the frozen soil that blankets the Arctic, may drain lakes and outweigh this expansion effect, says Webb.

The team theorized that thawing permafrost may decrease lake area by creating drainage channels and increasing soil erosion into the lakes. “Our findings suggest that permafrost thaw is occurring even faster than we as a community had anticipated,” Webb said. “It also indicates that the region is likely on a trajectory toward more landscape-scale drainage in the future.”

[Editor’s note: several other academic links are provided in the original article.]