Water Conservation and Management

 Dams are built not just for irrigation but for electricity generation, water supply for domestic and industrial uses, flood control, recreation, inland navigation and fish breeding. Hence, dams are now referred to as multi-purpose projects.

In India monsoon usually lasts from July to September. It is very irregular and unpredictable. India usually have no rains when needed and hence India requires highly sophisticated irrigation facilities and construction of reservoirs by which rain water can be stored and used all along the year. This is the major problem with Indian water potential though it has abundant rainfall. 

The geological structure of South India consists largely of hard crystalline rocks (peninsular shield), which makes digging wells difficult and expensive compared to the soft alluvial soil of the North.

• Karez is also called turpan water system. It is usually followed in China. Turpan's karez water system is made up of a horizontal series of vertically dug wells that are then linked by underground water canals to collect water.
  
• These are not followed in India.
  

• Sprinklers are used as irrigation tools that supply water to agricultural crops.
  
• It is very much useful as water is let out and sprinkled through small knobs. This checks wastage of water by seepage and evaporation.
  
• Apart from irrigation sprinklers are also used in industrial purposes.
  

In India monsoon usually lasts from July to September. It is very irregular and un predictable and hence India requires highly sophisticated irrigation facilities by which rain water can be stored and used all along the year. 

• Irrigation is the method by which water is collected, stored and supplied controllably when required by artificial means.
  
• All the given options like increase in salinization, groundwater depletion, etc., are not the outcome of irrigation projects. But sometimes reservoirs may result in floods due to loss of capacity in the reservoirs caused by sedimentation.
  

South India's geology features hard granite rock formations covered by thin soil layers. Traditional well-digging through this rock is extremely difficult and expensive. Tube wells requiring drilling equipment are more common, but still challenging compared to alluvial regions.

India's agriculture is heavily dependent on the monsoon, which is seasonal and often unpredictable. Irrigation is necessary to provide water during dry periods when rainfall is absent.

Irrigation is generally considered necessary in areas where annual rainfall is less than 75 cm, as these regions are prone to drought and water scarcity for crops.

In India, the irrigation of agricultural land is carried out maximum by Canals (29%). The longest canal in India is Indira Gandhi Canal about (650 km) this canal is also called Rajasthan feeder.

Canal irrigation is the most widespread and significant form of irrigation in India due to the country's extensive river systems and flat plains. Other methods like drip or sprinkler are modern but less prevalent in total area covered compared to canals.

In Eastern and Southern states, pond irrigation is a major source is a wrong statement. Wells and tube wells are the most important sources of irrigation followed by canal irrigation. Pond irrigation or rainwater harvesting form only a small portion of the irrigation system.

• The main source of water for rabi crops is rainwater, that has percolated into the ground. A good rain in winter spoils the rabi crops but is good for Kharif crops. 

Distilled water is purified water free of all dissolved salts. River, well and rain water is water in free state as collected in nature.