Water Resources — NCERT Solutions

The share of agriculture in total water use is expected to decline because the shares of industrial and domestic sectors are likely to increase with development. As the economy grows, more water will be needed for industries, urban use, and other non-agricultural purposes. So even though agriculture currently uses most of the water, its share will go down in the future.

Consumption of contaminated or unclean water can cause water-borne diseases and harm human health. The chapter explains that polluted water contains micro-organisms, chemicals, industrial wastes and toxic substances, which make it unfit for human use. Such water can spread illness, and toxic impurities like fluoride, nitrates, heavy metals and arsenic may seriously damage health. In this way, polluted water affects people directly and also worsens the quality of groundwater and aquatic life.

India has about 4 per cent of the world's water resources, while the total water available from precipitation in the country in a year is about 4,000 cubic km. But only 1,122 cubic km is the total utilisable water resource. The spatial distribution of water is uneven because it depends on precipitation, river basin size, catchment area, and topography. Areas with large catchments and high rainfall, such as the Ganga, Brahmaputra and Barak basins, have about 60 per cent of India's surface water resources, even though they cover only about one-third of the country's area. South Indian rivers have less utilisable flow in comparison, and seasonal rainfall concentration in the monsoon also causes uneven availability over time.

Depleting water resources can lead to social conflicts and disputes because water becomes scarce and different users, regions, and states compete for it. The chapter says tensions arise over the sharing and control of this scarce resource. If present trends continue, water demand may exceed supply and this can cause social upheaval and disruptions. For example, disputes can happen among communities, regions, and states over river water sharing. Pollution and overuse in one area can also create conflict by reducing usable water for others.

Watershed management means the efficient management and conservation of surface and groundwater resources in a watershed. It includes preventing runoff and storing and recharging groundwater through methods like percolation tanks and recharge wells. In a broader sense, it also includes the conservation, regeneration and judicious use of all natural and human resources in the watershed. Yes, it can play an important role in sustainable development because it helps balance natural resources and society, improves water availability, and supports long-term agriculture, livelihoods and environment. Its success depends greatly on community participation.