Chapter 3 — Water Resources

Water scarcity is when areas do not have sufficient water to meet the needs of people despite adequate rainfall, caused by over-exploitation, excessive use, and unequal access to water resources. It results from large populations, inadequate infrastructure, industrial demands, and unequal distribution rather than just low rainfall.

Large and growing urban populations create high demand that exceeds available resources. Cities have their own groundwater pumping devices in housing colonies that over-exploit fragile water resources, causing depletion. Additionally, much available water may be polluted by domestic and industrial wastes, making it hazardous for human use.

Multi-purpose river projects are dams built to serve multiple integrated uses: irrigation for agriculture, hydroelectric power generation, water supply for domestic and industrial use, flood control, recreation, inland navigation, and fish breeding. Examples include the Bhakra-Nangal project on the Sutlej-Beas rivers and Hirakud project on the Mahanadi.

Large dams disrupt natural river flow and sediment flow, causing poor habitats for aquatic life. They fragment rivers, blocking aquatic fauna migration for spawning. Sedimentation in reservoirs deprives floodplains of silt (natural fertilizer), causing land degradation. Dams can induce earthquakes, cause water-borne diseases, and pollution. They also submerge vegetation and soil, and ironically, have been unsuccessful at controlling floods during excessive rainfall.

Rainwater harvesting is a system to collect and store rainfall for later use. Traditional methods include rooftop rainwater harvesting using underground tankas (storage tanks), khadins and johads in arid regions, inundation channels in Bengal's floodplains, and bamboo drip irrigation in the Himalayas. Modern adaptations recharge groundwater and support agriculture and domestic water needs.

Rainwater falling on sloping roofs travels down PVC pipes into underground tankas or storage tanks. The first rainfall is not collected as it cleans the roofs and pipes. Subsequent rainfall is collected and stored until the next rainy season. In Rajasthan, some tankas were 6.1 metres deep. In places like Shillong, Meghalaya, rooftop harvesting provides 15-25% of household water needs.

A 200-year-old traditional system that uses bamboo pipes to tap perennial streams and springs. Water is transported over hundreds of metres and reduced to 20-80 drops per minute at plant sites through a series of bamboo channel sections. The system is gravity-fed and flow is controlled by manipulating pipe positions. About 18-20 litres of water enters the system initially.

Traditional rainwater harvesting structures found in arid and semi-arid regions of Rajasthan. Khadins are agricultural fields converted into rain-fed storage structures that allow water to stand and moisten the soil, found in Jaisalmer. Johads are similar structures found in other parts of Rajasthan, both designed to capture and retain seasonal rainfall.

The Jal Jeevan Mission (JJM) is a Government of India program to improve quality of life and ease of living, especially in rural areas. Its goal is to ensure every rural household receives assured supply of potable piped water at 55 litres per capita per day regularly on a long-term basis by ensuring functionality of tap water connections.

Karnataka and Andhra Pradesh governments raised objections to Maharashtra's diversion of more water at Koyna for a multipurpose project. This would reduce downstream flow in their states with adverse consequences for agriculture and industry, creating an inter-state water dispute.

Atal Bhujal Yojana (Atal Jal) is implemented in 8,220 water-stressed Gram Panchayats across 229 administrative blocks in 80 districts of seven states to bring behavioural change from water consumption to conservation. Pradhan Mantri Krishi Sinchayee Yojana ensures access to protective irrigation for agricultural farms, aiming to enhance water access and efficiency (har khet ko pani—water for every field) and reduce wastage.

Yes, the NCERT Class 10 Geography textbook is available free on CBSE PrepMaster with no sign-up required. You can download and access the Water Resources chapter along with all other class materials directly.