Land Soil Water Natural Vegetation and Wildlife Resources Test - 7

The running water cuts through the clayey soils and makes deep channels as gullies. In the Chambal basin such lands are called ravines. 

Dustbowl catastrophe is nothing but the dust storm that greatly damaged the ecology of US and Canadian prairies. The main reason for this storm was the wind erosion. Hence to prevent such catastrophes people should be taught well to prevent soil erosion. 

Soil conservation is a method of protecting soil from getting eroded either by wind or by water.

• Few soil conservation methods include:
  
• Graduated terrace steps which are commonly used to farm on hilly or mountainous terrain. Terraced fields decrease both erosion and surface runoff.
  
• Wind breaks: Row of trees or a fence, wall, or screen that provides shelter or protection of soil from the wind.
  
• Conservation tillage is a method of preparing soil from getting eroded. This technique involves leaving the previous year crop residues until the next crop is planted.

Steps can be cut out on the slopes making terraces. Terrace cultivation restricts erosion. Western and central Himalayas have well developed terrace farming. 

Water scarcity may be an outcome of large and growing population and consequent greater demands for water, and unequal access to it. A large population means more water not only for domestic use but also to produce more food. 

Reforestation is the natural or intentional restocking of existing forests and woodlands that have been depleted, usually through deforestation. Reforestation activities promote the gradual depletion of $$CO_2$$ from the atmosphere through absorption by plants.

Freshwater sources include:

• Groundwater - Water found in shallow aquifers beneath the earth's surface. This water is generally found at depths up to 2,000 feet deep.
  
• Precipitation: It is nothing but the rain water which is an important source of fresh water. In fact it is the purest natural source of freshwater.
  
• Surface water - Water found in streams, rivers, lakes, and reservoirs.
  

Answer: A- 3; B- 4; C- 1; D- 2

Land use: Land is used for different purposes such as agriculture, forestry, mining, building houses, roads and setting up of industries. This is known as land use.

Humus: Humus is defined as black organic matter formed in soil due to the decay of dead plant and animal matter.

Rock dams: These are the artificial embankments created by constructing mould of soil, clay, sand and rock. Main function is to prevent floods and soil erosion

Arable land: It is the land suitable for agriculture.

• India's rank in the world with respect to the amount of water available per person per year is 133.
  
• India is the second largest consumer of water in the world. Its consumption contributes 20.1% of world’s consumption of water.
  
• The per capita water available in India is 297.7 cubic meter.