Lecture 9: Water Cycle

Water cycle

• Continuous movement of water on, above, and below earth’s surface

• while on the move, water is changing states between liquid, vapor, and solid

• happening in the blink of an eye and over millions of years

• closed system

  • amount of water is constant

  • no water is created or destroyed

  • only transforms/moves between different resivors/environments

  • Benefits of closed system

    • accounting of fluxes

    • mass balance (water budget)

    • climate change evalutation

Fluxes of the hydrologic cycle

• evaporation

• precipitation

• runoff

• infiltration

• What energy drives the movement of these fluxes

  • sun = heat energy

    • evaporation

    • earths revolution, rotation, and tilt

    • temp and pressure gradients

  • wind energy

    • temp and pressure gradients

    • earths revolution, rotation, and tilt

  • colling with altitude

    • condensation/precipitation/rainfall/snow

  • gravity

    • precipiation falls on surface

  • gradient in temp and gradient in pressure drives the flow

Reservoirs of water cycles

• temp storage locations

• three main Reservoirs of water cycle

  • atmosphere (clouds)

    • evaporation brings water to atmosphere through vapor, which then condenses

    • clouds then move and transports water

    • water comes down as precipitation

  • surface (rivers, lakes, oceans, glaciers, wetlands)

    • evaporation takes away

    • precipitation brings water back

    • runoff carries water to a different surface

  • subsurface (soils and aquifers)

    • soils:

      • water seeps as infiltration, precolates

      • recharges aquifers

    • Aquifers:

      • can recharge surface water through base flow

      • which then is recharged by more surface water

      • discharged into ocean