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Define hydrological cycle, runoff, water balance, catchment

Short answer

The hydrologic cycle is the endless circulation of water among ocean, atmosphere, and land; runoff is the precipitated water flowing over land to streams; water balance equation, P−R−G−ET=ΔS, accounts for inputs, outputs, and storage change; a catchment is the drainage area bounded by ridges.

Define the following terms: hydrological cycle, runoff, water balance and catchment.

  • Hydrological cycle: The continuous circulation of water from oceans to atmosphere, to land and back to the oceans through evaporation, condensation, precipitation, infiltration and runoff, driven by solar energy and gravity.
  • Runoff: The part of precipitation that flows over the land surface and in channels to reach a stream, lake or sea. It includes surface runoff, interflow and base flow, and is usually expressed as discharge (m³/s) or depth (mm) over the catchment.
  • Water balance: The accounting of inflows, outflows and storage change of a region over a given time, based on conservation of mass: P−R−G−E−T=ΔSP - R - G - E - T = \Delta S.
  • Catchment (watershed or drainage basin): The area of land that drains to a given point on a stream, bounded by a ridge line called the water divide. All rain falling inside it (apart from losses) flows to that outlet.

✓ Answer checked by Claude Sonnet 5.5

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