Lake Qarun: It has transformed from a freshwater paradise into a salt lake that is threatened with disappearance, due to climate and human changes, and its impact on the ecosystem and wildlife.
In the heart of Egypt’s desert lies Lake Qarun, a vital mystery that reveals deep-rooted environmental transformations. This lake, which began as a source of fresh water, is today undergoing a dramatic transformation into a massive salt lake, threatening the life that once flourished on its banks.
Lake Qarun is located in the Fayoum Depression, 80 kilometers southwest of Cairo, and is considered one of the oldest natural lakes in the world. However, what we see today is just a shadow of what this great lake once was.
Shrinking lake
About 70,000 years ago, the Fayoum region was part of the Nile River, where water flowed to fill the depression and form a huge lake known as Lake Morris. This lake extended over an area of more than 1,700 square kilometers, and was connected to the Nile through a natural canal later known as Bahr Youssef.
During the twentieth century, the area of the lake witnessed gradual changes, as it decreased between 1926 and 1955 due to a shortage of Nile water, then increased between 1973 and 1984 as a result of increased agricultural drainage water into it, reaching 241 square kilometers in 2005.
The lake’s waters currently extend over an area of 55,000 acres and are home to many rare local and migratory birds. However, it is suffering from the effects of climate change and human activities that have turned it into an unsustainable environment for life.
The lake is a shallow natural lake, falling 43 meters below sea level. Its average depth is 4.5 metres, while its deepest point reaches 10 metres.
The deepest point in the lake is near the Golden Horn Island, while the depth decreases along the southern shore due to backfilling caused by draining drains.
Topographic maps indicate that the lake is longitudinal in shape, with a length of 47 kilometers, a maximum width of 8 kilometers west of Horn Island, and a total length of its shores of 150 kilometers. The northern shore of the lake is characterized by meandering as a result of the abundance of roughness and lack of human intervention.
The northern part of the lake includes the oldest paved road in the world in the Jabal Qatrani area, which is a rocky area that contains mammalian fossils that are millions of years old, including fossils of the oldest monkey in the world, “Aegyptius Monkey,” and the Fayoum elephant, “Fiumia,” in addition to fossils of the mermaid, the ancient Egyptian whale, and some fossilized trees.
Folk tales add a special charm to the area, as many believe that the name of the lake is attributed to Qarun, mentioned in the Holy Qur’an, and that his treasures lie beneath the surface of the lake and are guarded by a fairy or a mermaid.
Changing from fresh to salt water
Lake Qarun has transformed from completely fresh water to salt water that is more salinity than the Mediterranean Sea, due to the interruption of its connection with the Nile River and its transformation into a recipient of agricultural drainage water.
Historically, the lake was used to lower the Nile’s flood levels and store fresh water, but with the passage of time and increased agricultural drainage, the salt content in the lake has risen significantly.
Al-Bats and Al-Wadi drains are two of the main drains that feed the lake with irrigation water, and they represent about 60% and 31.18%, respectively, of the total wastewater.
In addition, 12 other sub-drains and 17 sewage plants drain into the lake, all of which carry farmland wastewater laden with fertilizer and sewage residues.
More salinity
The amounts of drainage reaching the lake gradually increased with the increase in the area of agricultural land, and reached 1,341,000 cubic meters per day in 2021.
Annually, the lake receives about 400 million cubic meters of agricultural drainage water, whose salinity ranges between 1.29% and 3.80‰.
The lake’s salinity increased from 10.5 g/L in 1906 to 38 g/L in 2019.
This increase in salinity is due to the lake being located in a desert area and its water being exposed to evaporation, in addition to being a closed internal lake not connected to the sea.
Researchers expect a further increase in salinity over the next century, which could turn the lake into a dead body of water devoid of any living organisms.
A threatened ecosystem
The lake’s ecosystem witnessed successive fluctuations that led to radical changes in its elements, and the lake was subjected to different exploitation systems that determined the structure and dynamics of the various organisms in the lake.
Historically, the lake was a rich habitat for Nile fish, but increasing salinity has led to the disappearance of most freshwater fish and a decline in fish production.
To compensate for the disappearance of Nile fish, the lake was stocked with marine fish species capable of adapting to the harsh new environment.
The composition of the lake’s fishing has changed, shifting from freshwater fish to fish that tolerate high levels of salinity.
The lake’s fishery production has fallen from 2,000 tons in 1981 to only 5 tons in 2022.
One of the biggest challenges facing the lake is the outbreak of isopod parasites that have heavily invaded the lake through young species imported from the Mediterranean.
These parasites feed on blood and cause serious problems for the host fish, leading to anemia, delayed growth, and death.
In addition, the lake’s water has been exposed to physical, chemical and biological pollution, which has led to the emission of unpleasant odors and made the water on its shores unsuitable for bathing.
Source: Lebanon Today
