UPPSC 2023 Prelims GS Paper-I · Question 8 of 150

Correct — D, Watershed. A watershed (also called a catchment or drainage basin) is the geographical unit of land that receives and collects precipitation, stores it in the soil, vegetation and groundwater, and releases it slowly through a common outlet such as a stream or river. This 'collect-store-release' hydrological function is exactly why watershed development is the basic unit of soil and water conservation.

• (a)Wet land — A wetland is a water-saturated ecosystem (marsh, swamp, mangrove). It holds water and supports biodiversity, but it is not defined as the land unit that collects rainfall and releases it through a common outlet.
• (b)Waste land — Wasteland is degraded or unproductive land — a land-use / land-quality category, not a hydrological unit that regulates water.
• (c)Water reserve — Not a standard geographical term for this function. A reservoir stores water, but it is not the surrounding land unit that collects and releases it.

A watershed is a geo-hydrological unit: all the land whose runoff drains to a single common outlet. Its boundary is the water divide (the ridge line separating adjacent basins). Rain falling anywhere within it is collected, part is stored in soil and groundwater, and the rest is released through the drainage network. Managing water at this natural unit is the basis of watershed development.

'Wetland' is the tempting distractor because wetlands also 'store' water — but the question stresses a land unit that collects and then releases water through an outlet, which is the catchment/watershed function, not a specific water-logged ecosystem.

• Watershed = area of land draining to a common outlet; also called catchment or drainage basin.
• The boundary of a watershed is the water divide (a ridge separating two basins).
• Watershed development (contour bunding, check dams, afforestation) cuts runoff and recharges groundwater.
• In India it is implemented via the Watershed Development Component of PMKSY (earlier the Integrated Watershed Management Programme).

• Confusing the watershed (the catchment area) with the water divide (the ridge separating two catchments).
• Confusing a wetland (an ecosystem) with a watershed (a drainage/land unit).

Definition-matching ('a unit that collects, stores and releases water = watershed'), or scheme-based (benefits/objectives of watershed development).

No directly related past PYQ was found.

• practice — not a real PYQ

  The line of high ground that separates two adjacent watersheds or drainage basins is called the:

  • (a)Water divide
  • (b)Thalweg
  • (c)Confluence
  • (d)Meander

  Answer(a) Water divide — the ridge marking a watershed's boundary.

• practice — not a real PYQ

  Watershed development programmes primarily aim to:

  • (a)Link perennial and seasonal rivers
  • (b)Conserve soil and recharge groundwater
  • (c)Build large multipurpose dams
  • (d)Desalinate seawater

  Answer(b) Conserve soil and recharge groundwater.