Class 10 Social Science (Geography)

Chapter: Water Resources

Water Scarcity (जल की कमी): Low availability of water compared to the demand for water. It is caused by over-exploitation, excessive use, and unequal access to water among different social groups.
Three-fourth (71%) of the Earth’s surface is covered with water, but only a small proportion of it accounts for freshwater that can be used.
Freshwater is mainly obtained from surface run-off and groundwater that is continually being renewed and recharged through the hydrological cycle.

Growing Population: Greater demand for domestic use and to produce more food.
Commercialization of Agriculture: Expanding irrigated areas for dry-season agriculture, which requires intensive water use (especially water-intensive crops like rice and sugarcane).
Industrialization: Industries make heavy demands on water and also require hydroelectric power to run them. Urbanization has further added to this problem.
Over-exploitation of Groundwater: Excessive pumping of groundwater for personal and agricultural use is lowering the water table in many cities and rural areas.
Water Pollution: Domestic and industrial wastes, chemical fertilizers, and pesticides pollute freshwater bodies, making them unfit for human use.

Multi-Purpose Project (बहुउद्देशीय नदी परियोजनाएँ): Dams built across rivers to serve multiple purposes simultaneously, such as irrigation, electricity generation, flood control, fish breeding, inland navigation, and recreation.
Jawaharlal Nehru proclaimed dams as the "Temples of Modern India" because they would integrate the development of agriculture and the village economy with rapid industrialization and urban growth.

Ecological Impact: Damming of rivers affects their natural flow, causing poor sediment flow and excessive sedimentation at the bottom of the reservoir.
Submergence: Reservoirs submerge existing vegetation and soil, leading to its decomposition over time.
Displacement: Local communities (tribals and farmers) are forced to give up their land and livelihood without adequate rehabilitation.
Water Conflicts: Interstate water disputes regarding sharing the costs and benefits of multi-purpose projects (e.g., Cauvery water dispute, Krishna-Godavari dispute).
Seismicity: Large dams can trigger earthquakes and cause water-borne diseases.

Rainwater Harvesting: A technique of increasing the recharge of groundwater by capturing and storing rainwater using structures such as rainwater harvesting wells, borewells, percolation pits, and check dams.
Traditional Methods in India:
- Tankas (टाँका): Underground tanks traditionally built in houses in arid and semi-arid regions of Rajasthan (like Bikaner, Phalodi, and Barmer) to store drinking water.
- Rooftop Rainwater Harvesting: Commonly practiced in Shillong (Meghalaya) and other parts of India to meet drinking water needs.
- Guls and Kuls: Diversion channels built in the western Himalayas for agriculture.
- Khadins and Johads: Structures built in arid regions to collect agricultural runoff.

Ramat (Karnataka): Remote village of Mysuru, where villagers installed rooftop rainwater harvesting systems in nearly 200 households to meet their water needs.
Bamboo Drip Irrigation System (Meghalaya): A 200-year-old system of tapping stream and spring water by using bamboo pipes to transport water over hundreds of meters to plant sites.

Hydrological Cycle (जल चक्र): The continuous movement of water on, above, and below the surface of the Earth.
Dam (बांध): A barrier across flowing water that obstructs, directs, or retards flow, often creating a reservoir, lake, or impoundment.
Aquifer (भूमजल स्तर): An underground layer of water-bearing permeable rock, rock fractures, or unconsolidated materials.
Palani (पालानी): A rainwater harvesting structure used traditionally.