bne IntelliNews – Avoiding water bankruptcy in drought-stricken southwest: What the US and Iran can learn from each other

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The water year 2021 ends on September 30, and it was another hot and dry year in the western United States, with most of the region in drought. Vital reservoirs for farms, communities and hydropower have fallen to dangerous levels.

The biggest blow came in August, when the U.S. government issued its first-ever water scarcity declaration for the Colorado River, triggering water use restrictions.

In response, farmers and cities in the Southwest are now finding new, often unsustainable, ways to meet their future water needs. Las Vegas has opened a low-level tunnel to Lake Mead, a reservoir in the Colorado River where water levels have reached unprecedented lows at 35% of capacity. Farmers are increasing the pumping of groundwater. Officials in Arizona, which will lose nearly a fifth of its river water allocation due to the new restrictions, have even floated the idea of ​​channeling water hundreds of miles from the Mississippi River.

These strategies hide a more fundamental problem: the uncontrolled growth in water consumption. The South West is in an “anthropogenic drought” created by the combination of natural water variability, climate change and human activities which are continually widening the gap between water supply and demand.

In the long run, this can lead to “water bankruptcy”, which means that the demand for water invariably exceeds the supply. Trying to manage this by increasing the water supply is doomed to failure.

In May of this year, water levels in Lake Oroville in northern California fell to 38% of their capacity. The boats are eclipsed by the exposed banks(Image: Frank Schulenburg / CC BY-SA 4.0).

More than 7,000 miles away, Iran faces water problems similar to those in the southwestern United States, but more serious. One of the driest years in the past five decades, following decades of poorly managed water resources, prompted warnings of water-related conflicts between Iranian provinces this year.

As environmental engineers and scientists – one of us is also a former deputy director of the Iranian Ministry of the Environment – we have closely studied the challenges of water in the two regions prone to drought. We believe past mistakes in the United States and Iran offer important lessons for future plans in the Southwestern United States and other areas that are increasingly experiencing drought and water scarcity. .

Pumping groundwater: a temporary solution with consequences

As the Colorado River’s water supply dwindles, farmers in the southwest are putting more chaff in already declining groundwater that has accumulated over thousands, if not millions of years. But it’s a short-term, unsustainable solution that has been tried in the United States and around the world – with major consequences. The High Plains Aquifer and the Central Valley of California are just two examples.

Iran offers a case study of what can go wrong with this approach, as our research shows. The country nearly doubled its groundwater extraction points between 2002 and 2015 in an effort to support a growing agricultural industry, which has drained aquifers to their exhaustion. As its water tables declined dramatically, the salinity of groundwater increased in aquifers to levels that might no longer be suitable for agriculture.

As the water-filled pores in the soil are drained, the weight of the overlying soil compresses them, causing aquifers to lose their water-holding capacity and accelerate land subsidence. The Iranian capital, Tehran, with more than 13 million inhabitants, sagged more than 12 feet (3.7 m) between 2003 and 2017. Likewise, parts of California are sinking at a rate of up to ‘to 1 foot (0.3 m) each year.

Kaveh Madani discusses the drying up of the Zayandeh Rud river bed in Isfahan, Iran.

Inter-basin water transfer: a Pandora’s box

Another proposal in the Southwest was to bring water elsewhere. In May, the Arizona legislature urged Congress to initiate a feasibility study to bring water from the Mississippi River to replenish the Colorado River. But that too has been tried.

In Iran, multiple inter-basin water transfer projects have doubled the flow of Zayandeh Rud, a river in the arid central part of the country. The influx of water supported unsustainable growth, creating demand without enough water to support it. In the dry years now, no one has enough water. Many people in Khuzestan – the region that provides water in central Iran – lost their livelihoods as their farms dried up, wetlands disappeared and livestock died of thirst. Residents of central Iran also lost crops due to the drought as the water supply was cut off. Both regions have seen protests turn violent this year.

A water tower next to a cemetery in Iran’s Isfahan province has suffered water stress (Photo: Petr Kraumann / CC BY-SA 3.0).

California diverted water from the eastern Sierra Nevada to support the growth of Los Angeles in the early 1900s, turning the once-prosperous Lake Owens Valley into a bowl of dust. Dust storm mitigation costs there now exceed $ 2 billion. Meanwhile, California needs more infrastructure and investment to meet its demand for water.

Another project, the California Aqueduct, was built in the 1960s to transfer water from the Sacramento-San Joaquin Delta in northern California to the Central Valley and the southern part of the state to support agriculture and part of urban demand. It also failed to close the gap between water demand and supply and pushed native fish species and ecologically important systems of economic and cultural significance in the delta to the point of collapsing.

Looking to the future in light of looming water bankruptcy

As the continued influx of people into the southwestern United States increases the demand for water in the face of dwindling water supplies, we must ask ourselves whether the southwest is heading for bankruptcy. water.

If there is no easy solution, a number of actions are possible.

First, recognize that water shortages cannot be alleviated only by increasing the water supply – it is also important to manage water demand.

US Geological Survey researcher Joseph Poland shows the high rate of subsidence in the San Joaquin Valley in California. USGS

There is great potential for water savings through efficient irrigation systems and precision agriculture, which could maintain the viability of agriculture in the region.

Cities can save water by reducing outdoor water loss and excessive water use, such as on ornamental lawns. Californians managed to reduce their water demand by more than 20% between 2015 and 2017 in response to severe drought conditions. Replanting cityscapes with native drought tolerant vegetation can help conserve water.

On the supply side, communities can consider non-traditional water sources, recycling and reuse of water in all sectors of the economy, and channeling runoff and flood water to recharge. underground aquifers.

There are also emerging technological solutions that could increase water resources in some areas, including fog water harvesting, which uses mesh sheets to capture moisture from fog, and desalination plants that transform water. seawater and saline groundwater into drinking water. A new desalination plant planned for Huntington Beach, California is awaiting final approval. However, the environmental consequences of these measures must be carefully considered.

The southwest monsoon returned this summer after a record year and a half of drought in the region, but it was not enough to end the drought there. Forecasts now suggest a high probability that a La Nina model will develop over the winter, meaning the southwest is likely to experience another drier-than-normal start through 2022.

Iran is already bankrupt, with demand exceeding supply. It will take much more than a wet year to overcome its water shortages.The conversation

Mojtaba Sadegh, assistant professor of civil engineering, Boise State University; Ali Mirchi, assistant professor of water resources engineering, Oklahoma State University; Amir AghaKouchak, Professor of Civil and Environmental Engineering, University of California, Irvine, and Kaveh Madani, Visiting Fellow, Yale University

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

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