Catchment hydrology

Catchment hydrology is the study of the hydrology in drainage basins. Catchments are areas of land where runoff collects to a specific zone. This movement is caused by water moving from areas of high energy to low energy to due the influence of gravity. Catchments often do not last for long periods of time as the water evaporates, drains into the soil, or is consumed by animals.

Water balance

Main article: Water balance

Catchment hydrology is based on the principal of continuity, which is used to perform a water balance on a catchment:

$I-O=dS/dt$,

where $I$ = inputs (P, precipitation + OW, occult water), $O$ = outputs (ET, evapotranspiration + R, runoff), and $dS/dt$ = the change in catchment storage over time.

Neglecting the minor inputs of occult water, the water balance can be revised to

$P-R-ET=dS/dt$.

Finally, considering a catchment on a long time scale, typically a year or more, removes the storage component from the equation:

$P-R=ET$.

(For more information see water balance)

Terminology

There are many terms involved with and related to catchment hydrology. These basic ones are taken from the glossary of terms in Kendall and McDonnell, 1998:

• aquifer
• baseflow
• catchment
• drainage divide
• evaporation
• evapotranspiration
• event water
• groundwater flow
• Horton flow
• hydrograph
• infiltration
• intensity
• interception
• overland flow
• pre-event water
• subsurface runoff
• subsurface stormflow
• surface runoff
• time of concentration
• transpiration

See also

• hydrology
• isotope hydrology
• hydrogeology
• groundwater
• agricultural hydrology
• Water quality
• Surface water
• Drinking water