Catchment hydrology: Difference between revisions

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Catchment hydrology is the study of 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 due to 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.^[1]

Water Sources

Catchment zones collect water from various sources such as surface runoff from snow cover and glaciers, and subsurface flow from groundwater, precipitation, and aquifers.^[2] Deposition from fog and clouds is another source of water for catchment zones.^[2] These sources of water collect together in a catchment area; which could provide drinking water for a nearby population.

Quantification

Precipitation in catchment areas is measured through rain gauges. A graduated ruler is used to measure the amount of snowfall. These measurements are taken in a specific location within the catchment and can be used to calculate water balance within the entire catchment area. The best studied catchments cover small areas because of the difficulty of these measurements.^[2] Water lost due to interception followed by evaporation represents a large portion of water loss. These measurements are used to obtain the change in water storage over time using the equation of continuity.^[2]

Topography

The surrounding topography of a catchment zone influences the flow vectors and direction that the water flows.^[3] Water flows from areas of high potential energy to low potential energy under the influence of gravity. The geometry of the slope leading to the catchment area influences the amount of water the catchment will contain.^[3]

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:

$P-R=ET$ .^[4]

(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:

References

^ Bren, Leon (2015), Bren, Leon (ed.), "The Basics of Catchment Hydrology", Forest Hydrology and Catchment Management: An Australian Perspective, Dordrecht: Springer Netherlands, pp. 1–21, doi:10.1007/978-94-017-9337-7_1, ISBN 978-94-017-9337-7
^ ^a ^b ^c ^d Buttle, James M. (1998), "Fundamentals of Small Catchment Hydrology", Isotope Tracers in Catchment Hydrology, Elsevier, ISBN 978-0-444-81546-0
^ ^a ^b Bren, Leon (2014), "Impacts of Native Forest Management on Catchment Hydrology", Forest Hydrology and Catchment Management, Dordrecht: Springer Netherlands, pp. 117–148, ISBN 978-94-017-9336-0
^ Kendall and McDonnell, 1998. Isotope Tracers in Catchment Hydrology. Elsevier

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 }}
 [[File:Nattai River aerial.jpg|thumb|350x350px|Catchment zone in Nattai, Australia containing drinking water.]]
+[[File:UpperSholayarDam Catchment area(part).jpg|thumb|350x350px|Catchment area near the Sholayar Dam]]
 '''Catchment hydrology''' is the study of [[hydrology]] in [[drainage basin]]s. Catchments are areas of land where [[Runoff (hydrology)|runoff]] collects to a specific zone. This movement is caused by water moving from areas of high energy to low energy due to 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.<ref>{{Citation|last=Bren|first=Leon|title=The Basics of Catchment Hydrology|date=2015|url=https://doi.org/10.1007/978-94-017-9337-7_1|work=Forest Hydrology and Catchment Management: An Australian Perspective|pages=1–21|editor-last=Bren|editor-first=Leon|place=Dordrecht|publisher=Springer Netherlands|language=en|doi=10.1007/978-94-017-9337-7_1|isbn=978-94-017-9337-7|access-date=}}</ref>
+==== Water Sources ====
+[[Drainage basin|Catchment]] zones collect water from various sources such as surface [[Surface runoff|runoff]] from [[Snow|snow cover]] and [[Glacier|glaciers]], and [[subsurface flow]] from [[groundwater]], [[precipitation]], and [[Aquifer|aquifers]].<ref name=":0">{{Citation|last=Buttle|first=James M.|title=Fundamentals of Small Catchment Hydrology|date=1998|url=http://dx.doi.org/10.1016/b978-0-444-81546-0.50008-2|work=Isotope Tracers in Catchment Hydrology|pages=|publisher=Elsevier|isbn=978-0-444-81546-0|access-date=}}</ref> Deposition from [[fog]] and [[Cloud|clouds]] is another source of water for catchment zones.<ref name=":0" /> These sources of water collect together in a catchment area; which could provide drinking water for a nearby population.
+[[File:Nattai_River_aerial.jpg|thumb|350x350px|Catchment zone in Nattai, Australia that contains drinking water.]]
+==== Quantification ====
+Precipitation in catchment areas is measured through [[Rain gauge|rain gauges]]. A graduated ruler is used to measure the amount of snowfall. These measurements are taken in a specific location within the catchment and can be used to calculate water balance within the entire catchment area. The best studied catchments cover small areas because of the difficulty of these measurements.<ref name=":0" /> Water lost due to [[Interception (water)|interception]] followed by [[evaporation]] represents a large portion of water loss. These measurements are used to obtain the change in water storage over time using the [[equation of continuity]].<ref name=":0" />
+[[File:UpperSholayarDam_Catchment_area(part).jpg|thumb|325x325px|Catchment area near the [[Sholayar Dam]]]]
+==== Topography ====
+The surrounding [[topography]] of a catchment zone influences the flow vectors and direction that the water flows.<ref name=":1">{{Citation|last=Bren|first=Leon|title=Impacts of Native Forest Management on Catchment Hydrology|date=2014|url=http://dx.doi.org/10.1007/978-94-017-9337-7_6|work=Forest Hydrology and Catchment Management|pages=117–148|place=Dordrecht|publisher=Springer Netherlands|isbn=978-94-017-9336-0|access-date=}}</ref> Water flows from areas of high [[potential energy]] to low potential energy under the influence of gravity. The geometry of the slope leading to the catchment area influences the amount of water the catchment will contain.<ref name=":1" />
 == Water balance ==