Lakes, Waterfalls and River Pollution
NCERT Class 9 • Contemporary India I • Chapter "Drainage" | NCERT Class 11 • India Physical Environment • Chapter "Drainage System"
Lakes, Waterfalls and River Pollution
Lakes are standing water bodies formed by glaciers, tectonic movement, river action or human effort. India's lakes range from freshwater Himalayan lakes to saltwater lakes of dry regions and coastal lagoons. Waterfalls occur where rivers cross a sudden drop, and many big rivers now face heavy pollution.
Types of Lakes
- Glacial lakes form in Himalayan basins scooped by ice, such as Wular in Kashmir, India's largest freshwater lake, formed by tectonic activity and fed by the Jhelum.
- Oxbow lakes form when a meander is cut off, common in the Ganga plain.
- Lagoons are coastal lakes cut off by sandbars, such as Chilika in Odisha, Pulicat on the Andhra-Tamil Nadu coast and Vembanad in Kerala.
- Salt lakes occur in dry areas, such as Sambhar in Rajasthan, used for salt production.
- Artificial lakes are reservoirs behind dams, such as Gobind Sagar behind Bhakra dam.
- Lakes moderate river flow, support fishing and tourism, and help maintain the local ecosystem.
| Lake | State | Type |
|---|---|---|
| Wular | Jammu and Kashmir | Freshwater |
| Chilika | Odisha | Lagoon |
| Pulicat | Andhra Pradesh, Tamil Nadu | Lagoon |
| Sambhar | Rajasthan | Salt |
| Vembanad | Kerala | Lagoon |
Major Waterfalls
| Waterfall | River | State |
|---|---|---|
| Jog or Gersoppa | Sharavati | Karnataka |
| Dhuandhar | Narmada | Madhya Pradesh |
| Shivasamudram | Kaveri | Karnataka |
| Hundru | Subarnarekha | Jharkhand |
How Waterfalls Form
A waterfall appears where a river crosses a hard rock band lying over softer rock, or drops down a fault scarp. The softer rock below is worn away faster, the ledge is undercut, and the fall slowly retreats upstream while digging a deep plunge pool at its base.
River Pollution
- Growing cities, industries and farms discharge sewage, effluents and fertiliser runoff into rivers.
- Falling flow in the dry season concentrates the pollutants further.
- The Ganga Action Plan was launched in 1985 as the first big river cleaning programme.
- The National River Conservation Plan later extended similar work to other rivers.
- The Namami Gange programme continues Ganga cleaning work today.
- Cleaning needs treatment plants plus steady minimum flow in the river.
Hindi me samjhein
लैगून समुद्र तट के पास बालू की रोक से बनी झील होती है, जैसे चिलिका। खारी झीलें शुष्क क्षेत्रों में बनती हैं क्योंकि पानी बाहर नहीं निकल पाता और वाष्पीकरण से नमक जमा हो जाता है।
Exam me kaise aata hai
- India's largest freshwater lake — Wular
- Jog falls is on which river — Sharavati
- Sambhar salt lake is in — Rajasthan
- Ganga Action Plan was launched in — 1985
UPSC/State PSC ke liye
- Chilika is a brackish lagoon whose salinity changes with the season and with the opening of its sea mouth.
- Cleaning a river needs both effluent treatment and an assured environmental flow; treatment alone does not work.
Yahan confuse hote hain
✗ Chilika is a freshwater lake | Chilika is a brackish lagoon | ✓
✗ Jog falls is on the Kaveri | Jog falls is on the Sharavati | ✓
✗ Sambhar is in Gujarat | Sambhar is in Rajasthan | ✓
Ek nazar me
- Lakes: glacial, oxbow, lagoon, salt and artificial.
- Wular is the largest freshwater lake; Chilika the largest lagoon.
- Jog falls on the Sharavati, Dhuandhar on the Narmada.
- Ganga Action Plan 1985, then the National River Conservation Plan.
Ab practice karein
Is chapter ke facts yaad hue ya nahi — ye ExamAtlas ke mock test se check karein. Drainage ke questions har exam me aate hain.