Question

Write the name of any four sources of surface water.

Hint:

For exam answers, first list four names (Rivers, Lakes, Reservoirs, Ponds) to secure marks, then add 1–2 lines on seasonality/quality or an example for extra credit.

Answer 1

Definition: Surface water refers to water that collects on the earth's surface in natural or artificial water bodies and flows along channels exposed to the atmosphere.
It contrasts with groundwater stored in aquifers below the surface.
Major sources of surface water (with notes and examples):
1.\; Rivers & streams: Flowing water systems fed by rainfall, snowmelt and springs; may be perennial (e.g., Ganga, Brahmaputra) or seasonal/ephemeral (monsoon streams). Provide irrigation, hydropower, navigation and municipal supply.
2.\; Lakes (natural): Tectonic, volcanic, glacial and ox-bow lakes store large volumes, regulate floods and support fisheries (e.g., Wular, Chilika—lagoon, Vembanad—backwater).
3.\; Reservoirs/Dams (artificial lakes): Created by impounding rivers—multi-purpose (irrigation, hydropower, flood control, water supply); examples include Bhakra, Hirakud.
4.\; Ponds/Tanks: Small impoundments common in villages and towns; vital for local drinking water, livestock, aquaculture and micro-irrigation; often community-managed traditional systems.
5.\; Wetlands/Marshes/Backwaters: Swamps, floodplains and estuarine wetlands act as sponges—store monsoon water, recharge groundwater, filter pollutants and support biodiversity.
6.\; Glaciers & snowmelt (as surface run-off source): Mountain snowfields and glaciers release meltwater seasonally, feeding rivers and high-altitude lakes; critical in dry seasons for snow-fed rivers.
7.\; Canals: Though man-made conveyance, canal networks carry and store surface water for irrigation and sometimes supply (distributaries, minors, field channels).
8.\; Lagoons/Estuaries (brackish): Semi-enclosed coastal water bodies; limited use for direct drinking but important for fisheries, salt-tolerant agriculture and industry cooling water.
Water quality characteristics (why treatment is needed):
- Physical: Turbidity, colour, suspended solids rise during monsoon due to runoff and erosion.
- Chemical: Nutrients (nitrate, phosphate), dissolved salts, organic pollutants (BOD/COD), heavy metals may increase from agriculture/industry.
- Biological: Pathogens (bacteria, viruses, protozoa) common in unprotected sources; hence filtration + disinfection (chlorination/UV/ozonation) are essential for potable supply.
Advantages vs limitations:
- Pros: Generally cheaper to abstract than deep groundwater; high yields; renewable with seasonal recharge; suitable for hydropower and navigation.
- Cons: High seasonal variability; higher pollution vulnerability; evaporation losses; conflicts among users and ecological flow needs.
Conservation & management:
- Watershed management: afforestation, contour bunding, check dams to reduce runoff peaks and enhance baseflow.
- Pollution control: sewage treatment, effluent standards, buffer zones, solid-waste management.
- Demand management: leakage control, efficient irrigation (drip/sprinkler), tiered tariffs, water reuse.
- Ecosystem protection: maintain environmental flows, protect wetlands as RAMSAR-type sites, regulate sand mining.
Answer to "any four sources" (names):
\[ \boxed{\text{Rivers, Lakes, Reservoirs (Dams), Ponds/Tanks}} \]
(Other acceptable sources include wetlands/backwaters, canals (as storage/conveyance), and snowmelt-fed surface run-off.)