TEST OF PRACTICAL KNOWLEDGE QUESTION (a) What is a lake? (b) Describe the formation of lakes by wind erosion. (c) identify three benefits of lakes to man.

Answer Details

(a) What is a lake?

A lake is a body of water, usually fresh but sometimes salty, that occupies a hollow or depression in the surface of the land and is completely surrounded by land. It is inland and standing (still) water.

(b) Formation of lakes by wind erosion (deflation)

In hot desert regions, strong winds pick up and blow away loose, dry sand and dust from the surface in a process called deflation. Where the wind removes the loose materials continuously from a soft or unconsolidated area, it scoops out a shallow, rounded depression called a deflation hollow. Wind erosion may continue downward until the floor of the hollow reaches the level of the underground water table. Water then seeps into the hollow, or rain water collects in it, forming a small lake known as a deflation-hollow lake or oasis. Such lakes are common in desert basins.

(c) Three benefits of lakes to man

1. Source of water: Lakes supply water for domestic use, irrigation and industry.
2. Fishing: Lakes support fishing, providing food and employment.
3. Transport, tourism and power: Lakes serve as inland waterways for navigation, attract tourists for recreation, and man-made lakes behind dams are used to generate hydro-electric power.