Water For The Middle East Could Be Provided By Desalination, Sparing Aquatic Life In The Process

Desalination is increasingly being utilised to manage water scarcity worldwide. Now, some 16,000 desalination units worldwide generate 35 trillion litres of freshwater every year. And to the north of the Red Sea, in Jordan, plans are underway for a massive desalination plant on the Gulf of Aqaba, tripling the country's annual desalination capacity from 4 billion to 350 billion litres.

But desalination tends to be energy intensive and produces saline effluent called brine. Returning brine to the ocean can be harmful to marine life. The Red Sea, the Arabian Gulf, and the Mediterranean Sea may be getting saltier as a result of desalination, according to studies.

When assessing whether current and future desalination programmes threaten marine life, through an increase in salinity levels across the Red Sea and the Gulf of Aqaba, it was found that the increase will likely be unnoticeable and lesser than natural seasonal changes.

An Essential Marine Environment

At its southern end, the Red Sea narrows into a shallow strait that leads to the Indian Ocean. The Red Sea is the only route to the Indian Ocean from the north, where it branches off into the Gulf of Aqaba.

Salinity is controlled by evaporation and the inward and outward flow of water from the Indian Ocean, as neither body of water receives any freshwater supply. The salinity and density of the Red Sea are increased as water that flows into the sea from the south evaporates and cools as it travels north. This saltier water is heavier, so it sinks near the Red Sea's northern end and returns to the Indian Ocean as a deeper layer of water moving southward.

The natural increase in salinity from the point where water enters the Red Sea to its highest point at the northern end of the Gulf of Aqaba is approximately 10%, from about 36.8 to 40.6 practical salinity units. (psu). A solution of one gramme of salt per thousand grammes of water is one psu. The local marine ecosystem has adapted to the higher salinity found there.

Sanganeb and Dungonab Bay Marine National Parks and Mukkawar Island Marine National Park are just a few of the many Unesco World Heritage Sites that can be found in the northern Red Sea. Coral reefs, seagrass beds, mudflats, mangroves, and beaches can all be found within our national parks. The scientific and environmental value of these areas is high since they are home to many different kinds of marine life, including the critically endangered dugong.

Most marine life can adapt to slightly different salinities, but they won't survive long-term shifts. Stylophora pistillata, a type of Red Sea coral, has had its photosynthesis and respiration rates reduced by as much as 50%, according to studies, when salinity levels were increased from 38 psu to 40 psu. If the salinity is maintained at this level for an extended period, most coral colonies will perish.

Adding Salt To The Ocean

“Our worst-case scenario entailed strong economic growth, increasing access to clean water, and decreasing desalination costs in the Middle East. By 2050, the Red Sea coast could desalinate about 10 trillion litres of water, while the Gulf of Aqaba could desalinate more than 2.5 trillion litres. In a less dire scenario, the population grows slowly and people consume less water at home. By 2050, the Red Sea and the Gulf of Aqaba could desalinate about 2 trillion litres of water and more than 560 billion litres, respectively,” stated Jonathan Chenoweth, Senior Lecturer in the Centre for Environment and Sustainability, University of Surrey.

In a less dire scenario, the population grows slowly and people consume less water at home. By 2050, the Red Sea and the Gulf of Aqaba could desalinate about 2 trillion litres of water and more than 560 billion liters, respectively.

In no case did the Red Sea's salinity rise by more than 0.1 percent. Compared to the seasonal change in salinity that occurs naturally, this rise would be negligible.

However, the Gulf of Aqaba is more compact and cut off from the rest of the Indian Ocean. Therefore, the natural range of salinity in the northern Gulf is between 40.2 and 40.75 parts per thousand. We calculated that under the high development scenario, salinity in the Gulf's northernmost regions could rise by 0.5%, from about 40.6 psu to 40.8 psu. However, even with this increase, natural variability still has a limited effect on salinity.

The medium growth scenario, on the other hand, would result in a shift that is smaller than the fluctuation that occurs due to the seasons naturally.

Resolving The Middle East's Water Crisis

Increasing desalination rates might not threaten local marine life if they are managed properly. This is crucial since desalination is expected to experience rapid expansion in the Middle East.

To accommodate 9 million people and water-intensive sectors like agriculture, Saudi Arabia plans to build a whole new metropolis in the country's north west by 2045. This city will be called Neom. Desalination plants will draw water from the Red Sea and the Gulf of Aqaba for the city's needs.

Increased desalination rates are not likely to significantly impact regional saline levels beyond the immediate neighbourhood of individual desalination plants. However, good plant design and rigorous environmental laws will be important to prevent environmental damage.

Brine from plants is discharged into the Red Sea through outfalls, where it is diluted quickly by mixing with the deeper water there. The brine can subsequently be diluted even further by being carried by ocean currents to the Indian Ocean.

The global need for desalination systems is rising. If done right, it might be a powerful tool for combating water scarcity without endangering sensitive marine habitats.