Notes of chapter 17 water for class 7th ( No spam)
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Explanation:
Water: Introduction
Water is a colourless liquid, which constitutes the major part of the earth for survival.
71% of the earth consists of water, hence earth is also called as blue planet.
Origin of water
The origin of water is found out to be from a type of meteorite.
The major sources of water for human use are lakes, rivers, ponds etc.
The chemical composition of water in earth is same as that of some meteorites.
Water Availability
Freshwater and saltwater
Freshwater is the pure and naturally occurring water on earth’s surface in rivers, lakes and underground as groundwater.
Saltwater is also called as saline water, which consists of some amounts of dissolved salts in it. Salt water is present in oceans, seas.
Statistics of availability of water
1. 71 % of Earth consists of water<
2. Out of this 71 %, 97% water is in oceans and seas, remaining 3 % is the freshwater in forms of lakes, rivers.
3. Out of this 3 % of freshwater, 30% is groundwater(not easily accessible), 69% are in the form glaciers, icebergs.( not accessible), out of the remaining 1% of water only 0.006% is used by the people for their uses.
Water Cycle
Physical properties of water
Physical properties of water:
Water is a colourless, odourless liquid.
Water can change its physical state. Eg: Liquid to solid state and vice versa, Liquid to gaseous state and vice versa.
Water cycle
The water cycle is the overall process, in which water circulates and is maintained for years to use.
The various processes involved in the water cycle are:
Evaporation
Condensation
Precipitation
Transpiration
Evaporation/Transpiration
Evaporation is the process, in which liquid phase is changed to a gaseous phase.
Transpiration is the process by which water evaporates from the surface of leaves through tiny pores called stomata.
Condensation
The process of changing the physical state from gaseous to liquid phase is called as condensation.
Precipitation
Precipitation occurs as a result of the condensation of water vapour in the atmosphere causing water droplets to become heavy and fall down in the form of rain, snow, hail etc.
To know more about Water Cycle, visit here.
Ground Water
Ground water
Groundwater is the water present underground or beneath the Earth’s surface in soil spaces and rock formations.
1. Water table – The water table is the upper surface of the ground filled with water.
2. Infiltration – The process of seeping of water from the surface of soil into the ground is called infiltration.
3. Aquifer – The places, in which groundwater is stored between the layers of rock below the water table.
Effect of water scarcity on plants
Plants need water to grow by absorbing nutrients from the soil.
If they do not get enough water, it affects their health and growth eventually killing the plant.
Water Management
Water management
Water management is the effective planning, distribution and use of water resources.
Some types of water management are as follows:
Rainwater harvesting or water harvesting: The process of collecting rainwater, which recharges the groundwater is called as rainwater harvesting or water harvesting.
Drip irrigation: Drip irrigation is the process of watering the crops directly to the roots of the plants using narrow pipes.
Bawris: A traditional way of rainwater storage and recharge
Introduction to Water: A Precious Resource
Water: Introduction
Water is a colourless liquid, which constitutes the major part of the earth for survival.
71% of the earth consists of water, hence earth is also called as blue planet.
Origin of Water
The origin of water is found out to be from a type of meteorite.
The major sources of water for human use are lakes, rivers, ponds etc.
The chemical composition of water in earth is same as that of some meteorites.
Answer:
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