Lake Kivu

Lake Kivu is a big lake in Africa.

It sits between two lands. These are Rwanda and the Congo.

There is a large island in the water. It is named Idjwi.

Deep in the lake, there is gas. This gas can come up to the top. It can be dangerous for people.

People use the gas to make power.

This helps give light to homes.

Many people catch fish in the lake.

It is a very busy place.

Lake Kivu is a large lake in Africa.

It sits on the border of Rwanda and the Congo. The lake is part of a rift valley. This is a place where the ground is pulling apart. This movement can cause volcanoes nearby.

There is a big island in the lake called Idjwi.

Many people live near the water. About two million people live in the lake area.

Deep in the water, there is gas. This includes methane and carbon dioxide. This gas comes from hot springs on the lake bed. If the gas bubbles up all at once, it is called a limnic eruption. This can be very dangerous for people.

To stay safe, people pull the gas out of the water. They use it to make power for homes. This is a helpful way to use the gas. Many people also use the lake to catch fish.

Small boats carry fishers out onto the water.

Lake Kivu is a huge lake in Africa.

It sits in the Albertine Rift on the border of Rwanda and the Democratic Republic of the Congo. This lake is part of a rift valley where the ground is slowly pulling apart. This movement causes volcanic activity in the area. The lake is Africa's eighth largest lake.

It has a very large island called Idjwi inside it. The water is quite deep, making it the twentieth deepest lake in the world.

Deep under the water, something very special happens. The lake has layers of water that do not mix well. This is called a meromictic lake. The bottom layers are saltier than the fresh water on top. These deep layers hold a lot of gas like methane and carbon dioxide. This gas comes from volcanic hot springs on the lake bed. Scientists think this gas might come from tiny living things too. This gas stays trapped deep down because of the heavy water.

Long ago, the lake behaved differently. It used to drain toward the north into the White Nile. About 13,000 to 9,000 years ago, volcanoes changed everything. Volcanic activity created mountains like the Virungas. These mountains blocked the old path of the water. Now, the water flows south into the Ruzizi River. This river then carries the water into Lake Tanganyika. A German officer named Gustav Adolf von Götzen first visited the lake in 1894.

There is a rare event that can happen here. It is called a limnic eruption. This is when the deep layers of gas suddenly overturn and rise up. This can be very dangerous for the two million people living nearby. The gas could cause a catastrophe or even lake tsunamis. Because of this, people work to stay safe. They use special tools to pull the methane out of the water.

This methane can be burned to make electricity for homes.

Many people also use the lake for food.

There are many types of fish living in the water. Some fish, like the Lake Tanganyika sardine, were brought here in 1959. Local people call these sardines 'Ndagala' or 'Isambaza.' They are very important for food and money in the area. Many fishers use small boats to catch them.

The lake is a busy place for both nature and people.

Lake Kivu is a massive African Great Lake located in the Albertine Rift. This rift is the western branch of the East African Rift system. The lake sits on the border between Rwanda and the Democratic Republic of the Congo.

It is Africa's eighth largest lake by surface area. The lake is also very deep. It is the twentieth deepest lake in the world by maximum depth. The water surface sits at an elevation of 1,460 meters above sea level.

The lake is a meromictic lake. This means the water has layers that do not mix together. The top layer is fresh water. The deeper layers become more saline, or salty, as you go down. Near the bottom, the salinity reaches about 6g/kg. This stratification keeps heavy gases trapped in the deep water. The lake bed sits on a rift valley. This valley is slowly being pulled apart by geological forces. This movement causes volcanic activity in the region. This activity is how the lake gets its unique chemical makeup.

Lake Kivu is one of only three lakes in the world that can undergo a limnic eruption. Lake Nyos and Lake Monoun in Cameroon are the other two. A limnic eruption occurs when deep, stratified layers of water overturn. This overturn releases massive amounts of dissolved carbon dioxide. The lake also contains high levels of methane. This methane is produced by the microbial reduction of volcanic minerals.

Scientists believe volcanic activity or climate changes might trigger these eruptions. If an eruption happens, it could be a catastrophe. It could release enough carbon dioxide to suffocate the two million people living nearby. It might even cause lake tsunamis.

The history of the lake's flow changed many thousands of years ago. Originally, Lake Kivu drained toward the north. This water contributed to the White Nile. Between 13,000 and 9,000 years ago, volcanic activity changed the landscape. Volcanism created mountains like the Virungas. These mountains blocked the old outlet to the Nile watershed. As a result, water was forced to flow south. It now empties into the Ruzizi River. The Ruzizi flows into Lake Tanganyika. The first recorded European visitor was Gustav Adolf von Götzen in 1894.

There is a massive amount of energy trapped in the lake's depths. The bottom contains an estimated 60 cubic kilometers of methane. If burned in a modern plant, this could generate 40,000 megawatts for one year. This is six times the peak power of the Grand Coulee Dam. However, the lake also holds 60 cubic kilometers of carbon dioxide. This gas is a major risk to local life. In Swahili, outgassing events are called mazuku, meaning "evil wind." These winds can kill people, animals, and plants. Because of this risk, companies are working to extract the methane safely.

Companies like KivuWatt use offshore barge platforms to manage the gas.

They pump gas-rich water up from the lake bed. As the water rises, the pressure drops. This causes the methane, carbon dioxide, and hydrogen sulfide to bubble out. The purified methane is then sent through an underwater pipeline. This methane is used in onshore gas engines to create electricity. This project can increase Rwanda's energy capacity by 20 times. In 2016, a $200 million power plant was operating at 26 MW.

The lake is also home to many living things. There are 28 described fish species in the water. Many are endemic, meaning they are found nowhere else. This includes 15 species of Haplochromis cichlids. In 1959, an agronomist named Alphonse Collart introduced the Lake Tanganyika sardine. Local people call this fish 'Ndagala' or 'Isambaza.'

This fish is very important for food and the economy. Many fishers use boats to catch them.

The lake also contains Idjwi, which is the tenth-largest island in a lake.