Water Resources and Conservation
NCERT Class 10 • Contemporary India II • Chapter "Water Resources" | NCERT Class 10 • Science • Chapter "Management of Natural Resources"
Water Resources and Conservation
Water covers most of the earth's surface but only a very small fraction is fresh water available for human use. In India the problem is not only quantity but distribution, since water is abundant in some regions and seasons and scarce in others.
Scarcity and Multipurpose Projects
- Water scarcity arises from growing population, expanding irrigation, industrial demand, pollution and uneven rainfall.
- Scarcity can exist even where rainfall is high, if the water is polluted or if it runs off before it can be stored.
- Multipurpose river valley projects serve irrigation, electricity, flood control, water supply, navigation, fisheries and recreation together.
- Bhakra Nangal on the Satluj, Hirakud on the Mahanadi and Damodar Valley projects are important examples.
- Their benefits are real, but they also submerge land and forest and displace people, often tribal communities.
- Large dams can also change the river's flow and sediment pattern, affecting fisheries and downstream farming.
- Sedimentation slowly reduces the storage capacity of a reservoir, shortening the working life of the project.
Conservation Methods
- Rainwater harvesting collects rain from rooftops and open ground and either stores it or lets it recharge the groundwater.
- Watershed management treats the whole slope from ridge to valley, using contour bunds, check dams and tree cover.
- Traditional systems include the ahar pyne of south Bihar, khadin and tanka of Rajasthan, kul of Himachal, and tanks of the south.
- Micro irrigation through drip and sprinkler delivers water directly to the root and saves a great deal of it.
- Recycling and reuse of treated water in industry and for gardening reduces demand on fresh supply.
- Repairing leaks, metering supply and pricing water sensibly reduce waste in towns and cities.
- Groundwater must be recharged at least as fast as it is withdrawn, or the water table keeps falling.
| Method | How It Works | Where Suited |
|---|---|---|
| Rainwater harvesting | Collects and recharges rain | Rooftops, open ground |
| Watershed management | Treats ridge to valley as one unit | Hilly and rain fed areas |
| Micro irrigation | Water directly to the root | Water scarce farming |
| Traditional systems | Local storage and channels | Region specific |
Watershed management — the treatment of an entire drainage area from ridge to valley as a single unit for conserving soil and water.
Exam me kaise aata hai
- The traditional irrigation system of south Bihar is — ahar pyne
- Collecting rain for storage or recharge is — rainwater harvesting
- Bhakra Nangal is built on which river — the Satluj
- Drip and sprinkler together are called — micro irrigation
UPSC/State PSC ke liye
- Large dams distribute their costs and benefits unevenly: the benefits go to farms and cities downstream while the costs fall on those displaced upstream.
- Groundwater is a common pool resource, so each user has an incentive to pump more while the aquifer falls for everyone, which is why regulation is so difficult.
Yahan confuse hote hain
✗ Water scarcity happens only where rainfall is low | It also occurs where water is polluted or not stored | ✓
✗ Multipurpose projects have only benefits | They also submerge land and displace people | ✓
✗ Rainwater harvesting only means storing water | It also recharges groundwater | ✓
Ek nazar me
- Fresh water is a small fraction of total water and is unevenly distributed.
- Multipurpose projects serve many purposes but submerge land and displace people.
- Rainwater harvesting, watershed management and micro irrigation conserve water.
- Traditional systems such as ahar pyne remain locally effective.