An ancient system that could bring water to dry areas

SOME of Africa’s dry areas face serious water shortages due to minimal rainfall. An ancient system of drawing water from aquifers, the “qanat system,” could help.

Gaathier Mahed, an environmental scientist and expert on the management of groundwater, has studied the feasibility of these systems.

How does the qanat system work?

There are bodies of water underground known as aquifers, some of which can be found at the tops of valleys or near mountains.

A qanat system taps these aquifers and, using underground tunnels, moves the water, using gravity, over many kilometres. The tunnel then exits at a lower-lying area.

When the water exits the tunnel, farmers can use it to irrigate their crops. People can also access the water along the stretch of the tunnel using wells. It is a system that is managed by everyone, and its benefits are shared.

Everybody has a vested interest and a role to play. Community bonds can be strengthened — in stark contrast to tensions we see over water resources today.

The digging of the tunnel and development of the system over large areas of land is labour intensive and can take many years. The qanats cover many kilometres and needs to be maintained every year, by cleaning out the silt build-up.

Knowledge of building qanats and maintaining them is being lost. People have migrated from rural areas to cities and adopted boreholes in certain areas instead.

Some qanats are drying up due to over exploitation of the water resource.

Why should the system be used more widely?

In most instances people in arid areas drill wells to access groundwater. These boreholes have a lifespan and eventually new wells have to be drilled. Pumps and materials do not last forever, and wells can get clogged by microbial organisms and fine material in the subsurface.

First, the qanat is sustainable as it works with gravity and no electricity is needed.

It can even be used to create clean energy. For instance, in Iran cold air that comes out of qanat tunnels is used to cool the interior of large buildings.

Second, water lost to evaporation is minimal in comparison to surface water supplies.

Third, it can have a wide scale impact. Qanats are multiple kilometres long and once this water hits a floodplain, it can irrigate multiple hectares of land.

Fourth, it fosters social cohesion. Many people, with different skills, are involved in maintaining the system.

Fifth, the lifespan of the system extends beyond that of a deep water well, which is only about 20 years. Tunnels do not clog as easily as wells.

Lastly, the quality of water coming from the mountains is much better than water on the plains. It will have lower salinity and be better for crops and people.

The year 2023 was a year of record-breaking heat, devastating storms and floods, deepening droughts and raging wildfires. These events showed how climate change is affecting the global water cycle and our livelihoods.

Scores of countries had record average annual temperatures in 2023. Severe droughts hit three continents. The world’s largest forests suffered, with Canada battling huge fires and the Amazon hit hard by drought.

The most obvious sign of the climate crisis is the unprecedented heat waves that swept the globe in 2023. Earth’s hottest year on record gave us a glimpse of what a typical year with 1.5 degrees Celsius of warming may look like.

Global warming consistently more than 1.5 degrees Celsius above pre-industrial levels is expected to have extreme and irreversible impacts on the Earth system.

Some 77 countries experienced their highest average annual temperature in at least 45 years.

The high temperatures were often accompanied by low air humidity.

The relative air humidity of the global land surface was the second-driest on record in 2023.

Rapid drying of farms and forests caused crops to fail and forests to burn.

Lack of rain and soaring temperatures intensified multi-year droughts in vulnerable regions such as South America, the Horn of Africa and the Mediterranean.

The past two decades have significantly increased air temperatures and reduced air humidity. This continuing trend toward drier conditions is threatening agriculture, biodiversity and overall water security. These conditions heighten heat stress and increase the water needs of people, crops and ecosystems.

Scorching conditions inflicted extensive damage on the world’s largest forests.

The world’s forests have been soaking up a lot of fossil fuel emissions. That is because plant photosynthesis absorbs carbon dioxide from the atmosphere. Large disturbances like fire and drought reduce or even reverse that function

A change in circulation and sea temperatures in the Pacific Ocean to El Niño conditions influenced the global water cycle in 2023. But this happened against a backdrop of increasing sea surface temperatures due to global warming.

Rising sea surface and air temperatures have been intensifying the strength and rainfall intensity of monsoons, cyclones and other storm systems. At the start of 2024, the greatest risk of developing or intensifying drought appears in Central and South America (except southern Brazil and Uruguay), southern Africa and western Australia.

Regions that received much rainfall towards the end of 2023 are unlikely to develop drought for at least several months. These include the Sahel region and the Horn of Africa, northern Europe, India, China and South-East Asia.

The events of 2023 show how the threat of ongoing climate change to our planet and lives is growing by the year.

There were many such events in 2023, and the human and economic toll was large. These events should not be viewed as isolated incidents but as part of a broader emerging pattern.

Globally, the frequency and intensity of rainfall events and flooding are increasing.

At the same time, there are also more and faster developing droughts, or flash droughts, that can cause crop failure and destructive wildfires within weeks or months.

With the global food challenge, biodiversity crisis and an extremely urgent need to reduce carbon emissions, these droughts and fires are among our greatest global threats.

Overall, 2023 provided a stark reminder of the consequences of our continued reliance on fossil fuels and the urgent need but apparent inability of humanity to act decisively to cut greenhouse gas emissions. — The Conversation.