Introduction to Hydrology

  • Hydrology - Encompasses the occurrence, distribution, movement, and properties of the waters of the earth.
  • Hydrologic Cycle - global sun-drive process whereby water is transported from the oceans to the atmosphere to the land back to the sea.
  • Major components of hydrologic cycle
    • [P] Precipitation - rain, snow, sleet, or hail that falls to the ground.
    • [I] Infiltration - the process by which water on the ground surface enters the soil.
    • [E] Evaporation - the process that changes liquid water to gaseous water
    • [T] Transpiration - the process of water vapor being released from plants and soil.
    • [R] Surface Runoff - travels over the ground surface and through surface channels to leave a catchment area called a drainage basin or watershed
    • [G] Ground Water Flow - movement of water underground.
    • [ET] Evapotranspiration - the sum of all processes by which water moves from the land surface to the atmosphere via evaporation and transpiration. (Special component for calculation purposes).
    • \

 The Hydrologic Cycle.

 Distribution of Precipitation input

  • Hydrologic Budget - Accounting of the inflow, outflow, and storage of water in a designated hydrologic system.