In the heart of the Egyptian desert lies Lake Qarun, a vital enigma revealing profound environmental transformations. This lake, which began as a source of fresh water, is today witnessing a tragic shift towards a massive salt lake, threatening the life that once thrived 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.
The 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 Moeris. This lake stretched over an area of more than 1,700 square kilometers and was connected to the Nile via a natural canal later known as Bahr Yussef.
During the 20th century, the lake’s area witnessed gradual changes, shrinking between 1926 and 1955 due to a shortage of Nile water, then increasing between 1973 and 1984 as a result of increased drainage of agricultural wastewater into it, reaching 241 square kilometers in 2005.
The lake’s water currently extends over an area of 55,000 acres and is home to many rare local and migratory birds. However, it suffers from the effects of climate change and human activities that have turned it into an unsustainable environment for life.
The lake is one of the shallow natural lakes, dropping 43 meters below sea level, with an average depth of 4.5 meters, while the deepest point is 10 meters.
The deepest point in the lake is located near the Golden Horn Island, while the depth decreases along the southern shore due to landfilling operations resulting from the drainage of drains.
Topographic maps indicate that the lake is longitudinal in shape, with a length of 47 kilometers and a maximum width of 8 kilometers west of Al-Qarn Island, and a total shoreline length of 150 kilometers. The northern shore of the lake is characterized by meandering due to the abundance of snouts and the lack of human intervention.
The northern part of the lake includes the oldest paved road in the world in the Jabal Qatrani area, a rocky area containing mammalian fossils millions of years old, including fossils of the oldest monkey in the world, “Aegyptopithecus,” and the Fayoum elephant, “Fayumia,” in addition to fossils of the sea bride and the ancient Egyptian whale and some petrified trees.
Folk tales add a special charm to the region, as many believe that the lake’s name is attributed to Qarun mentioned in the Holy Quran, and that his treasures lie beneath the surface of the lake, guarded by a genie or mermaid.
The Transformation from Fresh Water to Salt Water
Lake Qarun has transformed from completely fresh water to salt water that exceeds the salinity of the Mediterranean Sea, due to the disconnection of its connection to the Nile River and its transformation into a recipient of agricultural wastewater.
Historically, the lake was used to reduce the level of the Nile flood and store fresh water, but over time and with the increase in the drainage of agricultural wastewater, the percentage of salts in the lake rose significantly.
Al-Bats and Al-Wadi drains are the main drains that feed the lake with irrigation water, representing about 60% and 31.18%, respectively, of the total wastewater.
In addition, 12 other sub-drains and 17 sewage stations flow into the lake, all carrying wastewater from agricultural lands loaded with fertilizer residues and sewage.
More Salinity
The amounts of drainage reaching the lake gradually increased with the increase in the area of agricultural land, reaching one million and 341 thousand cubic meters per day in 2021.
The lake receives annually about 400 million cubic meters of agricultural wastewater, the salinity of which ranges between 1.29% and 3.80‰.
The salinity rate in the lake rose from 10.5 grams/liter in 1906 to 38 grams/liter in 2019.
This increase in salinity is attributed to the lake’s location in a desert area and the exposure of its water to evaporation, in addition to being a closed inland lake that is not connected to the sea.
Researchers expect a further increase in salinity during the next century, which may lead to the transformation of the lake into a dead water body devoid of any living organisms.
Threatened Ecosystem
The lake’s ecosystem has witnessed successive fluctuations that have led to radical changes in its elements, and the lake has been subject to different exploitation systems that were the reason for determining the structure and dynamics of the various living organisms in the lake.
Historically, the lake was a rich home for Nile fish, but the increased salinity led to the disappearance of most freshwater fish and a decrease in fish production.
To compensate for the disappearance of Nile fish, the lake was supplied with marine fish species capable of adapting to the harsh new environment.
The composition of fishing in the lake has changed, shifting from freshwater fish to fish that tolerate high levels of salinity.
Fish production in the lake has decreased 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 severely invaded the lake through juveniles of imported species 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 subjected to physical, chemical, and biological pollution, which has led to the emission of unpleasant odors and made the water of its beaches unsuitable for swimming.
source: 961 today
