Category: Drought

‘We live in a desert. We have to act like it’: Las Vegas faces reality of drought

Read the full story in The Guardian.

Water investigators track down wasteful homeowners and public turf torn up to conserve scarce water supplies

Colorado’s water scarcity may finally be coming for your local duck pond

Read the full story from KUNC.

Water supplies are so tight in the West that most states keep close watch over every creek, river, ditch and reservoir. A complex web of laws and rules is meant to ensure that all the water that falls within a state’s boundaries is put to use or sent downstream to meet the needs of others.

To prevent waste and avoid sparking an interstate legal battle, Colorado has started cracking down on what may seem like a drop in the proverbial bucket — illegal ponds.

The drought in the western U.S. is getting bad. Climate change is making it worse

Read the full story from NPR.

By almost every measure, the drought in the Western U.S. is already one for the record books…That’s creating a fundamental threat to the way Western water systems operate, because they were built around the idea that the climate would remain constant. Historical climate data such as river flows and rainfall totals told engineers how big to build reservoirs and canals. The data also told them how much water was available to divide up among cities and farms.

There’s a danger in over-simplifying water conservation

Read the full story from Morning AgClips.

You hear it every time drought returns to California: “Turn off the faucet when you brush your teeth.” “Collect shower water in a bucket before it warms up.”

While valuable, these tried and true drought resilience strategies can also deflect attention from the monumental challenges posed by droughts to natural areas, waterways, agriculture and people in California. Far-sighted and discerning management of the state’s annual precipitation and groundwater is critical, particularly as droughts become more frequent due to climate change, said Faith Kearns, the academic coordinator of UC’s California Institute for Water Resources.

Another dangerous fire season is looming in the Western U.S., and the drought-stricken region is headed for a water crisis

Dry conditions across the West follow a hot, dry year of record-setting wildfires in 2020. Communities were left with scenes like this, from California’s Creek Fire. Amir Aghakouchak/University of California Irvine

by Mojtaba Sadegh (Boise State University), Amir AghaKouchak (University of California, Irvine), and John Abatzoglou (University of California, Merced)

Just about every indicator of drought is flashing red across the western U.S. after a dry winter and warm early spring. The snowpack is at less than half of normal in much of the region. Reservoirs are being drawn down, river levels are dropping and soils are drying out.

It’s only May, and states are already considering water use restrictions to make the supply last longer. California’s governor declared a drought emergency in 41 of 58 counties. In Utah, irrigation water providers are increasing fines for overuse. Some Idaho ranchers are talking about selling off livestock because rivers and reservoirs they rely on are dangerously low and irrigation demand for farms is only just beginning.

Scientists are also closely watching the impact that the rapid warming and drying is having on trees, worried that water stress could lead to widespread tree deaths. Dead and drying vegetation means more fuel for what is already expected to be another dangerous fire season.

U.S. Interior Secretary Deb Haaland and Agriculture Secretary Tom Vilsack told reporters on May 13, 2021, that federal fire officials had warned them to prepare for an extremely active fire year. “We used to call it fire season, but wildland fires now extend throughout the entire year, burning hotter and growing more catastrophic in drier conditions due to climate change,” Vilsack said.

As climate scientists, we track these changes. Right now, about 84% of the western U.S. is under some level of drought, and there is no sign of relief.

Color-coded map showing drought
The U.S. Drought Monitor for mid-May shows nearly half of the West in severe or extreme drought. National Drought Mitigation Center/USDA/NOAA

The many faces of drought

Several types of drought are converging in the West this year, and all are at or near record levels.

When too little rain and snow falls, it’s known as meteorological drought. In April, precipitation across large parts of the West was less than 10% of normal, and the lack of rain continued into May.

Rivers, lakes, streams and groundwater can get into what’s known as hydrological drought when their water levels fall. Many states are now warning about low streamflow after a winter with less-than-normal snowfall and warm spring temperatures speeding up melting. The U.S. Bureau of Reclamation announced it would cut off water to a canal serving farms in the Klamath Project on the Oregon-California border because of low water supplies. It also warned that Lake Mead, a giant Colorado River reservoir that provides water for millions of people, is on pace to fall to levels in June that could trigger the first federal water shortage declaration, with water use restrictions across the region.

Dwindling soil moisture leads to another problem, known as agricultural drought. The average soil moisture levels in the western U.S. in April were at or near their lowest levels in over 120 years of observations.

Four US maps showing drought levels of precipitation, vapor pressure deficit, evapotranspiration and streamflow
Four signs of drought. Climate Toolbox

These factors can all drive ecosystems beyond their thresholds – into a condition called ecological drought – and the results can be dangerous and costly. Fish hatcheries in Northern California have started trucking their salmon to the Pacific Ocean, rather than releasing them into rivers, because the river water is expected to be at historic low levels and too warm for young salmon to tolerate.

Snow drought

One of the West’s biggest water problems this year is the low snowpack.

The western U.S. is critically dependent on winter snow slowly melting in the mountains and providing a steady supply of water during the dry summer months. But the amount of water in snowpack is on the decline here and across much of the world as global temperatures rise.

Several states are already seeing how that can play out. Federal scientists in Utah warned in early May that more water from the snowpack is sinking into the dry ground where it fell this year, rather than running off to supply streams and rivers. With the state’s snowpack at 52% of normal, streamflows are expected to be well below normal through the summer, with some places at less than 20%.

Map of western U.S. showing many areas with low snowpack
Snowpack is typically measured by the amount of water it holds, known as snow water equivalent. National Resource Conservation Service

Anthropogenic drought

It’s important to understand that drought today isn’t only about nature.

More people are moving into the U.S. West, increasing demand for water and irrigated farmland. And global warming – driven by human activities like the burning of fossil fuels – is now fueling more widespread and intense droughts in the region. These two factors act as additional straws pulling water from an already scarce resource.

As demand for water has increased, the West is pumping out more groundwater for irrigation and other needs. Centuries-old groundwater reserves in aquifers can provide resilience against droughts if they are used sustainably. But groundwater reserves recharge slowly, and the West is seeing a decline in those resources, mostly because water use for agriculture outpaces their recharge. Water levels in some wells have dropped at a rate of 6.5 feet (2 meters) per year.

The result is that these regions are less able to manage droughts when nature does bring hot, dry conditions.

Fish pour out of a pipe into a bay.
California fish hatcheries have started trucking their salmon to the Pacific Ocean because the rivers they are usually released into are too low and warm. AP Photo/Rich Podroncelli

Rising global temperatures also play several roles in drought. They influence whether precipitation falls as snow or rain, how quickly snow melts and, importantly, how quickly the land, trees and vegetation dry out.

Extreme heat and droughts can intensify one another. Solar radiation causes water to evaporate, drying the soil and air. With less moisture, the soil and air then heat up, which dries the soil even more. The result is extremely dry trees and grasses that can quickly burn when fires break out, and also thirstier soils that demand more irrigation.

Alarmingly, the trigger for the drying and warming cycle has been changing. In the 1930s, lack of precipitation used to trigger this cycle, but excess heat has initiated the process in recent decades. As global warming increases temperatures, soil moisture evaporates earlier and at larger rates, drying out soils and triggering the warming and drying cycle.

Fire warnings ahead

Hot, dry conditions in the West last year fueled a record-breaking wildfire season that included the largest fires on record in Colorado and California.

As drought persists, the chance of large, disastrous fires increases. The seasonal outlook of warmer and drier-than-normal conditions for summer and fire season outlooks by federal agencies suggest another tough, long fire year is ahead.

This article was updated with a statement from Secretaries Deb Haaland and Tom Vilsack.

Mojtaba Sadegh, Assistant Professor of Civil Engineering, Boise State University; Amir AghaKouchak, Associate Professor of Civil & Environmental Engineering, University of California, Irvine, and John Abatzoglou, Associate Professor of Engineering, University of California, Merced

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

Interstate water wars are heating up along with the climate

Aerial view of Lake Powell on the Colorado River along the Arizona-Utah border. AP Photo/John Antczak

by Robert Glennon (University of Arizona)

Interstate water disputes are as American as apple pie. States often think a neighboring state is using more than its fair share from a river, lake or aquifer that crosses borders.

Currently the U.S. Supreme Court has on its docket a case between Texas, New Mexico and Colorado and another one between Mississippi and Tennessee. The court has already ruled this term on cases pitting Texas against New Mexico and Florida against Georgia.

Climate stresses are raising the stakes. Rising temperatures require farmers to use more water to grow the same amount of crops. Prolonged and severe droughts decrease available supplies. Wildfires are burning hotter and lasting longer. Fires bake the soil, reducing forests’ ability to hold water, increasing evaporation from barren land and compromising water supplies.

As a longtime observer of interstate water negotiations, I see a basic problem: In some cases, more water rights exist on paper than as wet water – even before factoring in shortages caused by climate change and other stresses. In my view, states should put at least as much effort into reducing water use as they do into litigation, because there are no guaranteed winners in water lawsuits.

Dry times in the West

The situation is most urgent in California and the Southwest, which currently face “extreme or exceptional” drought conditions. California’s reservoirs are half-empty at the end of the rainy season. The Sierra snowpack sits at 60% of normal. In March 2021, federal and state agencies that oversee California’s Central Valley Project and State Water Project – regional water systems that each cover hundreds of miles – issued “remarkably bleak warnings” about cutbacks to farmers’ water allocations.

The Colorado River Basin is mired in a drought that began in 2000. Experts disagree as to how long it could last. What’s certain is that the “Law of the River” – the body of rules, regulations and laws governing the Colorado River – has allocated more water to the states than the river reliably provides.

The 1922 Colorado River Compact allocated 7.5 million acre-feet (one acre-foot is roughly 325,000 gallons) to California, Nevada and Arizona, and another 7.5 million acre-feet to Utah, Wyoming, Colorado and New Mexico. A treaty with Mexico secured that country 1.5 million acre-feet, for a total of 16.5 million acre-feet. However, estimates based on tree ring analysis have determined that the actual yearly flow of the river over the last 1,200 years is roughly 14.6 million acre-feet.

The inevitable train wreck has not yet happened, for two reasons. First, Lakes Mead and Powell – the two largest reservoirs on the Colorado – can hold a combined 56 million acre-feet, roughly four times the river’s annual flow.

But diversions and increased evaporation due to drought are reducing water levels in the reservoirs. As of Dec. 16, 2020, both lakes were less than half full.

Second, the Upper Basin states – Utah, Wyoming, Colorado and New Mexico – have never used their full allotment. Now, however, they want to use more water. Wyoming has several new dams on the drawing board. So does Colorado, which is also planning a new diversion from the headwaters of the Colorado River to Denver and other cities on the Rocky Mountains’ east slope.

Much of the U.S. Southwest and California are in extreme or exceptional drought.
Drought conditions in the continental U.S. on April 13, 2021. U.S. Drought Monitor, CC BY-ND

Utah stakes a claim

The most controversial proposal comes from one of the nation’s fastest-growing areas: St. George, Utah, home to approximately 90,000 residents and lots of golf courses. St. George has very high water consumption rates and very low water prices. The city is proposing to augment its water supply with a 140-mile pipeline from Lake Powell, which would carry 86,000 acre-feet per year.

Truth be told, that’s not a lot of water, and it would not exceed Utah’s unused allocation from the Colorado River. But the six other Colorado River Basin states have protested as though St. George were asking for their firstborn child.

In a joint letter dated Sept. 8, 2020, the other states implored the Interior Department to refrain from issuing a final environmental review of the pipeline until all seven states could “reach consensus regarding legal and operational concerns.” The letter explicitly threatened a high “probability of multi-year litigation.”

Utah blinked. Having earlier insisted on an expedited pipeline review, the state asked federal officials on Sept. 24, 2020 to delay a decision. But Utah has not given up: In March 2021, Gov. Spencer Cox signed a bill creating a Colorado River Authority of Utah, armed with a US$9 million legal defense fund, to protect Utah’s share of Colorado River water. One observer predicted “huge, huge litigation.”

How huge could it be? In 1930, Arizona sued California in an epic battle that did not end until 2006. Arizona prevailed by finally securing a fixed allocation from the water apportioned to California, Nevada and Arizona.

Southwest Utah’s claim to Colorado River water is sparking conflict with other western states.

Litigation or conservation

Before Utah takes the precipitous step of appealing to the Supreme Court under the court’s original jurisdiction over disputes between states, it might explore other solutions. Water conservation and reuse make obvious sense in St. George, where per-person water consumption is among the nation’s highest.

St. George could emulate its neighbor, Las Vegas, which has paid residents up to $3 per square foot to rip out lawns and replace them with native desert landscaping. In April 2021 Las Vegas went further, asking the Nevada Legislature to outlaw ornamental grass.

The Southern Nevada Water Authority estimates that the Las Vegas metropolitan area has eight square miles of “nonfunctional turf” – grass that no one ever walks on except the person who cuts it. Removing it would reduce the region’s water consumption by 15%.

Water rights litigation is fraught with uncertainty. Just ask Florida, which thought it had a strong case that Georgia’s water diversions from the Apalachicola-Chattahoochee-Flint River Basin were harming its oyster fishery downstream.

That case extended over 20 years before the U.S. Supreme Court ended the final chapter in April 2021. The court used a procedural rule that places the burden on plaintiffs to provide “clear and convincing evidence.” Florida failed to convince the court, and walked away with nothing.

Robert Glennon, Regents Professor and Morris K. Udall Professor of Law & Public Policy, University of Arizona

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

Climatologist: Vegetation plays a role in developing flash droughts

By Lisa Sheppard, Prairie Research Institute

Farmland vegetation and grasses can affect both the frequency and extent of flash droughts, say scientists at the Illinois State Water Survey (ISWS), who hope to better understand the phenomenon and improve early warnings.

Flash droughts intensify quickly compared to normal droughts, magnifying the resulting economic and environmental effects. Typical droughts can take many months or years to reach peak intensity, whereas flash droughts can become severe within weeks.

In the past few years, scientists have begun examining flash droughts to learn more about the climatic, atmospheric, and environmental conditions that affect them.

“The flash drought is a new type of rapidly developing drought, and there is still a lack of consensus in its definition,” said ISWS climatologist Liang Chen. “Ever since the drought in the summer of 2012, flash droughts have received more attention from the scientific community, particularly because the impact on crop production is so much greater and stakeholders have much less time to prepare.”

The 2012 drought in the central U.S.—one of the most intense droughts on record—was later categorized as a flash drought because of how swiftly it developed. Soil moisture conditions that were normal in early June declined to what is considered exceptional drought just eight weeks later.

Chen and his colleagues studied the climatology of warm-season flash drought occurrence in the United States using data from 1979 to 2014 and experiments in a climate model. Findings showed that vegetation greening over the spring and summer months can significantly increase flash drought occurrence, particularly in the Great Plains and in the western U.S. The extent of flash droughts is also affected, but the duration is not.

A primary reason for the drought sensitivity to vegetation is the enhanced evapotranspiration that can deplete soil moisture with little effect on the health of vegetation until the soil moisture approaches the wilting point of plants. With evapotranspiration, water is transferred from the land to the atmosphere through evaporation from the soil and transpiration from plants.

Variable rainfall, leading to changes in soil moisture, also can potentially cause more flash drought events.

In the Midwest and in the eastern U.S., adequate rainfall and humidity typically provide enough moisture for vegetation and can offset reductions in soil moisture, so flash droughts are more sensitive to vegetation phenology in semi-arid and arid areas than in humid regions.

Climate projections show increasing drought conditions in large parts of the country, so there will likely be an increased risk of flash droughts in a warming climate, Chen said. Although irrigation is a potential option to decrease the risk of flash droughts, groundwater depletion in some areas of the country will likely pose challenges for meeting irrigation water demand.

The results of early studies such as this one can be influenced by the climate model used and the way that flash drought is defined. Chen and his colleagues plan to conduct more experiments to find more answers on how flash droughts develop in their future work.

This study was published in the Journal of Hydrometeorology. State Climatologist Trent Ford, also an author on this study, was interviewed for a previous story about flash drought.

Media contacts: Liang Chen, liangch@illinois.edu
news@prairie.illinois.edu

This post originally appeared on the Prairie Research Institute blog. Read the original post.

Climate change is hitting the Colorado River ‘incredibly fast and incredibly hard’

Read the full story at AzCentral.

The warming climate is intensifying drought, contributing to fires and drying out the river’s headwaters, sending consequences cascading downstream.

Two-thirds of Earth’s land is on pace to lose water as the climate warms – that’s a problem for people, crops and forests

Cape Town residents queued up for water as the taps nearly ran dry in 2018. Morgana Wingard/Getty Images

by Yadu Pokhrel (Michigan State University)

The world watched with a sense of dread in 2018 as Cape Town, South Africa, counted down the days until the city would run out of water. The region’s surface reservoirs were going dry amid its worst drought on record, and the public countdown was a plea for help.

By drastically cutting their water use, Cape Town residents and farmers were able to push back “Day Zero” until the rain came, but the close call showed just how precarious water security can be. California also faced severe water restrictions during its recent multiyear drought. And Mexico City is now facing water restrictions after a year with little rain.

There are growing concerns that many regions of the world will face water crises like these in the coming decades as rising temperatures exacerbate drought conditions.

Understanding the risks ahead requires looking at the entire landscape of terrestrial water storage – not just the rivers, but also the water stored in soils, groundwater, snowpack, forest canopies, wetlands, lakes and reservoirs.

We study changes in the terrestrial water cycle as engineers and hydrologists. In a new study published Jan. 11, we and a team of colleagues from universities and institutes around the world showed for the first time how climate change will likely affect water availability on land from all water storage sources over the course of this century.

We found that the sum of this terrestrial water storage is on pace to decline across two-thirds of the land on the planet. The worst impacts will be in areas of the Southern Hemisphere where water scarcity is already threatening food security and leading to human migration and conflict. Globally, one in 12 people could face extreme drought related to water storage every year by the end of this century, compared to an average of about one in 33 at the end of the 20th century.

These findings have implications for water availability, not only for human needs, but also for trees, plants and the sustainability of agriculture.

Where the risks are highest

The water that keeps land healthy, crops growing and human needs met comes from a variety of sources. Mountain snow and rainfall feed streams that affect community water supplies. Soil water content directly affects plant growth. Groundwater resources are crucial for both drinking water supplies and crop productivity in irrigated regions.

While studies often focus just on river flow as an indicator of water availability and drought, our study instead provides a holistic picture of the changes in total water available on land. That allows us to capture nuances, such as the ability of forests to draw water from deep groundwater sources during years when the upper soil levels are drier.

The declines we found in land water storage are especially alarming in the Amazon River basin, Australia, southern Africa, the Mediterranean region and parts of the United States. In these regions, precipitation is expected to decline sharply with climate change, and rising temperatures will increase evaporation. At the same time, some other regions will become wetter, a process already seen today.

Map of water storage loss
The map shows the projected change in terrestrial water storage by the end of the 21st century, compared to the 1975-2005 average, under a mid-range scenario for global warming. A continuum of yellow to orange to dark red reflects increasing severity of loss of stored water; teal to blue to dark blue reflects increasing gains in stored water. Yadu Pokhrel, et al, Nature Climate Change, 2021, CC BY-ND

Our findings for the Amazon basin add to the longstanding debate over the fate of the rainforest in a warmer world. Many studies using climate model projections have warned of widespread forest die-off in the future as less rainfall and warmer temperatures lead to higher heat and moisture stress combined with forest fires.

In an earlier study, we found that the deep-rooted rainforests may be more resilient to short-term drought than they appear because they can tap water stored in soils deeper in the ground that aren’t considered in typical climate model projections. However, our new findings, using multiple models, indicate that the declines in total water storage, including deep groundwater stores, may lead to more water shortages during dry seasons when trees need stored water the most and exacerbate future droughts. All weaken the resilience of the rainforests.

A new way of looking at drought

Our study also provides a new perspective on future droughts.

There are different kinds of droughts. Meteorological droughts are caused by lack of precipitation. Agricultural droughts are caused by lack of water in soils. Hydrological droughts involve lack of water in rivers and groundwater. We provided a new perspective on droughts by looking at the total water storage.

Diagram of water cycle
Water in the environment. U.K. Met Office

We found that moderate to severe droughts involving water storage would increase until the middle of the 21st century and then remain stable under future scenarios in which countries cut their emissions, but extreme to exceptional water storage droughts could continue to increase until the end of the century.

That would further threaten water availability in regions where water storage is projected to decline.

Changes driven by global warming

These declines in water storage and increases in future droughts are primarily driven by climate change, not land-water management activities such as irrigation and groundwater pumping. This became clear when we examined simulations of what the future would look like if climate conditions were unchanged from preindustrial times. Without the increase in greenhouse gas emissions, terrestrial water storage would remain generally stable in most regions.

If future increases in groundwater use for irrigation and other needs are also considered, the projected reduction in water storage and increase in drought could be even more severe.

Yadu Pokhrel, Associate Professor of Civil and Environmental Engineering, Michigan State University

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

Error Correction Means California’s Future Wetter Winters May Never Come

Read the full story from the Pacific Northwest National Laboratory.

California and other areas of the U.S. Southwest may see less future winter precipitation than previously projected by climate models. After probing a persistent error in widely used models, researchers at the Department of Energy’s Pacific Northwest National Laboratory estimate that California will likely experience drier winters in the future than projected by some climate models, meaning residents may see less spring runoff, higher spring temperatures, and an increased risk of wildfire in coming years.

Earth scientist Lu Dong, who led the study alongside atmospheric scientist Ruby Leung, presented her findings at the American Geophysical Union’s fall meeting on Tuesday, Dec. 1, and will answer questions virtually on Wednesday, Dec. 16.

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