India’s surface water and groundwater, how each sector uses water, polluted rivers, and conserving water through watershed management and rainwater harvesting.
| Water in a year | about 4,000 cubic km from rain; 1,122 cubic km utilisable; 432 cubic km replenishable groundwater |
| Use by agriculture | 89% of surface water, 92% of groundwater (industry 2% and 5%; homes 9% of surface water) |
| A sector’s use | per cent × total used ÷ 100 |
| Per person | water supplied ÷ population (litres per person per day) |
| Tank capacity | length × width × depth (m3); 1 m3 = 1,000 litres |
| Polluted stretches | Yamuna between Delhi and Etawah; Ganga at Kanpur |
Suppose 800 cubic km of surface water is used in a year (89% by agriculture, 2% by industry, 9% by homes) and 500 cubic km of groundwater (92% by agriculture). (a) How much surface water does each sector use, and how much groundwater does agriculture use? (b) Why may agriculture’s share fall in future? (c) Name one way to reduce farm water use.
Working: 89%, 2% and 9% of 800; 92% of 500
Answer: (a) agriculture 712, industry 16, domestic 72 cubic km; groundwater for agriculture 460 cubic km (b) industrial and domestic demand will grow with development (c) e.g. drip or sprinkler irrigation, less water-hungry crops