A lake is a depression on the surface of the earth where water has accumulated.
Types of Lakes
According To the Nature of Water
- Fresh water lakes which contain fresh water.
- Salty lakes which have salty water.
According To the Mode of Formation of Depression They Occupy
by Earth or Tectonic Movements
Faulted or Rift Valley Lakes
During Rift Valley formation some parts of the rift valley floor sunk more than others. A long narrow and deep depression formed. Water from seepage and rain accumulated into these depressions to form lakes.
Down Warped and Tilted Lakes
Tensional and compression forces caused some parts of the earth’s crust to up warp while others down warped. A shallow depression formed. The depression may also be filled with water from rain or groundwater. In the case of Lake Victoria Rivers Kafu, Kagera and Katonga were tilted eastwards and Nyando, Yala and Nzoia continued flowing westwards adding water into the depression.
L.Victoria is the second largest freshwater lake after L.Superior. Has a maximum depth of 87m deep. Other examples of lakes are L. Kyoga and Wamala.
Lake formed by water accumulating into a crater. Are usually salty. A crater lake formed on an explosion crater is called maar.
Lava Dammed Lakes
Formed as a result of water accumulating on the upstream side of a lava barrier across a river. Highly viscous lava erupts across the course of a river. It solidifies and blocks the river forming a lava dam. The river’s water accumulates behind the lava dam. A narrow and winding lake is formed e.g. Lakes Bunyonyi, Mutanda and Bulera in Uganda.
(i) Corrie/Tarn Lakes
Lake formed when water from melting snow accumulates into a corrie/cirque e.g. Teleki, Nanyuki and Hidden tarns on Mt. Kenya.
Finger-like on a glaciated valley. Glacier erodes the floor of a u-shaped valley. It over deepens some of its sections. Elongated hollow results. Water from melting ice accumulates into it forming a lake.
Lakes formed when ground water accumulates in a depression formed by wind deflation and abrasion. Wind continuously erodes the earth’s crust by deflation and abrasion. The water-bearing rocks are reached. Water oozes from the water table into the hollow or water from flash floods may accumulate in it to form temporary lakes called pans e.g. in Quattara depression between Egypt and Libya and Etosha pan in Namib.
Lakes formed when rain or ground water accumulates in depressions formed in limestone rocks when rainwater containing a weak carbonic acid dissolves limestone rocks e.g. Lakes Barber in Morrocco and Ojikoto in Namibia.
Formed when river deposition occurs cutting off a section of a pronounced meander e.g. oxbow lakes Shakababo and Mukunguya at lower part of Tana.
Lakes are formed when wave deposition occurs across the mouth of a river or where the coastline changes suddenly enclosing a body of calm water. Waves break at an angle. The longshore drift causes materials to be progressively arranged across a river’s mouth resulting in a body of calm water called a lagoon/sound.
These are Lakes formed when water accumulates behind dams constructed across rivers resulting into a large man made reservoir called a man-made lake e.g. behind Seven Forks Dam and Lakes Volta in Ghana and Nasser in Egypt.
This is a bank of earth or stones built across a river to provide water for farming.