# Baseflow

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Stream flow between precipitation events

**Baseflow** (also called **drought flow**, **groundwater recession flow**, **low flow**, **low-water flow**, **low-water discharge** and **sustained** or **fair-weather runoff**) is the portion of the [streamflow](/source/Streamflow) that is sustained between precipitation events, fed to streams by delayed pathways. It should not be confused with [groundwater flow](/source/Groundwater_flow). Fair weather flow is also called base flow.[1]

## Importance

Baseflow is important for sustaining human [centers of population](/source/Center_of_population) and [ecosystems](/source/Ecosystem). This is especially true for [watersheds](/source/Drainage_basin) that do not rely on [snowmelt](/source/Snowmelt). Different ecological processes will occur at different parts of the [hydrograph](/source/Hydrograph). During the baseflow ascending limb, there is frequently more [stream](/source/Stream) area and [habitat](/source/Habitat) available for water-dependent species, spawning [salmon](/source/Salmon) for example. During the recession limb, there is increasingly less stream area, and [indigenous](/source/Indigenous_(ecology)) species are more adept at surviving in low flow conditions than [introduced species](/source/Introduced_species).

## Geology

Baseflow is derived from [bedrock](/source/Bedrock) [water storage](/source/Water_storage) near surface [valley](/source/Valley) [soils](/source/Soil) and [riparian zones](/source/Riparian_zone). Water [percolates](/source/Percolation) to [groundwater](/source/Groundwater) and then flows to a [body of water](/source/Body_of_water). Baseflow depletion curve is the declining of baseflow/groundwater and soil reserves.[2] The volume and rate of water moving as baseflow can be affected by [macropores](/source/Macropore), [micropores](/source/Micropores), and other fractured conditions in the soil and shallow [geomorphic](/source/Geomorphology) features. Infiltration to recharge subsurface storage increases baseflow. Evapotranspiration reduces baseflow because trees absorb water from the ground. In the fall baseflow can increase before it starts to rain because the trees drop their leaves and stop drinking as much water.[3] [River incision](/source/River_incision) can decrease the baseflow by lowering the [water table](/source/Water_table) and [aquifer](/source/Aquifer).[4]

Good baseflow is connected to surface water that is located in permeable, soluble, or highly fractured bedrock. Bad baseflow is in [crystalline](/source/Crystal) or massive bedrock with minor fracturing and doesn't store water. Losing reaches is when the water flow decreases as it travels downstream and is fracturing deeper than surface water or in karst geology because limestone and dolomite high storage. Gaining reaches is when flow increases as it travels downstream. Gaining reaches are common in humid mountainous regions where the water table is above the surface water and the water flows from high head to low head following [Darcy's law](/source/Darcy's_law).[4]

## Measurement

Methods for identifying baseflow sources and residence/transit time include using [solutes](/source/Solutes) and [tracers](/source/Flow_tracer). Solutes that originate in distinct areas of the watershed can be used to source baseflow-geochemical signatures. Tracers may be inserted into different parts of the watershed to identify flow paths and transit times.[5]

Methods for summarizing baseflow from an existing streamflow record include event based low flow statistics,[6] flow duration curve,[7] metrics that explain proportioning of baseflow to total flow,[8] and the baseflow recession curve which can be used on ungauged streams based on empirical relationship between watershed characteristics and baseflow at gauged sites.[9]

Certain parameters of baseflow, such as the [mean residence time](/source/Mean_baseflow_residence_time) and the baseflow recession curve, can be useful in describing the mixing of waters (such as from precipitation and groundwater) and the level of groundwater contribution to streamflow in catchments.[10]

## Anthropogenic effects

[Anthropogenic](/source/Human_impact_on_the_environment) effects to baseflow include [forestry](/source/Forestry), [urbanization](/source/Urbanization), and [agriculture](/source/Agriculture). [Forest cover](/source/Forest_cover) has high infiltration and recharge because of tree roots. Removal of forest cover can cause a short-term increase in mean flow and baseflow because there is less interception and [evapotranspiration](/source/Evapotranspiration).[11] Urbanization includes a re-organization of surface and subsurface pathways so that water is flushed through catchments because of reduced hydraulic resistance, [Manning's n](/source/Manning's_n), channels and impervious surfaces which decreases infiltration. In urban areas water is often imported from outside the watershed from deep wells and [reservoirs](/source/Reservoir). The pipes that transport the water often leak 20-25% to the subsurface which can actually increase baseflow. Agriculture can lower baseflow if water diverted from stream for irrigation, or can raise baseflow if water is used from a different watershed. Pastures can increase compaction and reduce organic matter with reduces infiltration and baseflow.[11]

## See also

- [Baseflow residence time](/source/Baseflow_residence_time)

- [Hydrograph](/source/Hydrograph)

- [Time of concentration](/source/Time_of_concentration)

## References

1. **[^](#cite_ref-1)** Kendall and McDonnell (1998). [*Isotope Tracers in Catchment Hydrology*](https://web.archive.org/web/20080705040054/http://www.cof.orst.edu/cof/fe/watershd/research_publications_book.php). Elsevier. Archived from [the original](http://www.cof.orst.edu/cof/fe/watershd/research_publications_book.php) on July 5, 2008. Retrieved July 10, 2009.

1. **[^](#cite_ref-2)** Ward, Andy; Trimble, Stanley (2003). *Environmental Hydrology, Second Edition*. CRC Press. [ISBN](/source/ISBN_(identifier)) [978-1-4200-5661-7](https://en.wikipedia.org/wiki/Special:BookSources/978-1-4200-5661-7).

1. **[^](#cite_ref-3)** Bierman, Paul R. (2013-12-27). *Key concepts in geomorphology*. Montgomery, David R. New York, NY: University of Vermont University of Washington. [ISBN](/source/ISBN_(identifier)) [9781429238601](https://en.wikipedia.org/wiki/Special:BookSources/9781429238601). [OCLC](/source/OCLC_(identifier)) [868029499](https://search.worldcat.org/oclc/868029499).

1. ^ [***a***](#cite_ref-:1_4-0) [***b***](#cite_ref-:1_4-1) Mount, Jeffrey F. (1995). *California rivers and streams : the conflict between fluvial process and land use*. Berkeley: University of California Press. [ISBN](/source/ISBN_(identifier)) [9780520916937](https://en.wikipedia.org/wiki/Special:BookSources/9780520916937). [OCLC](/source/OCLC_(identifier)) [42330977](https://search.worldcat.org/oclc/42330977).

1. **[^](#cite_ref-5)** Glynn, Pierre D.; Plummer, L. Niel (2005-03-01). "Geochemistry and the understanding of ground-water systems". *Hydrogeology Journal*. **13** (1): 263–287. [Bibcode](/source/Bibcode_(identifier)):[2005HydJ...13..263G](https://ui.adsabs.harvard.edu/abs/2005HydJ...13..263G). [doi](/source/Doi_(identifier)):[10.1007/s10040-004-0429-y](https://doi.org/10.1007%2Fs10040-004-0429-y). [ISSN](/source/ISSN_(identifier)) [1431-2174](https://search.worldcat.org/issn/1431-2174). [S2CID](/source/S2CID_(identifier)) [129716764](https://api.semanticscholar.org/CorpusID:129716764).

1. **[^](#cite_ref-6)** O'Keeffe, Jay (2009). "Sustaining river ecosystems: balancing use and protection". *Progress in Physical Geography: Earth and Environment*. **33** (3): 339–357. [Bibcode](/source/Bibcode_(identifier)):[2009PrPG...33..339O](https://ui.adsabs.harvard.edu/abs/2009PrPG...33..339O). [doi](/source/Doi_(identifier)):[10.1177/0309133309342645](https://doi.org/10.1177%2F0309133309342645). [S2CID](/source/S2CID_(identifier)) [131587514](https://api.semanticscholar.org/CorpusID:131587514).

1. **[^](#cite_ref-7)** Stedinger, JR; Vogel, RM; Foufoula-Georgiou, E (1993). *Handbook of Hydrology*. McGraw-Hill.

1. **[^](#cite_ref-8)** Bloomfield, J.P.; Allen, D.J.; Griffiths, K.J. (2009-06-30). ["Examining geological controls on baseflow index (BFI) using regression analysis: An illustration from the Thames Basin, UK"](http://nora.nerc.ac.uk/id/eprint/7510/1/Bloomfield%20Allen%20Griffiths%202009.pdf) (PDF). *Journal of Hydrology*. **373** (1–2): 164–176. [Bibcode](/source/Bibcode_(identifier)):[2009JHyd..373..164B](https://ui.adsabs.harvard.edu/abs/2009JHyd..373..164B). [doi](/source/Doi_(identifier)):[10.1016/j.jhydrol.2009.04.025](https://doi.org/10.1016%2Fj.jhydrol.2009.04.025). [ISSN](/source/ISSN_(identifier)) [0022-1694](https://search.worldcat.org/issn/0022-1694).

1. **[^](#cite_ref-9)** Posavec, Kristijan; Bacani, Andrea; Nakic, Zoran (2006-05-26). "A Visual Basic Spreadsheet Macro for Recession Curve Analysis". *Ground Water*. **44** (5): 060526082055001––. [Bibcode](/source/Bibcode_(identifier)):[2006GrWat..44..764P](https://ui.adsabs.harvard.edu/abs/2006GrWat..44..764P). [doi](/source/Doi_(identifier)):[10.1111/j.1745-6584.2006.00226.x](https://doi.org/10.1111%2Fj.1745-6584.2006.00226.x). [ISSN](/source/ISSN_(identifier)) [0017-467X](https://search.worldcat.org/issn/0017-467X). [PMID](/source/PMID_(identifier)) [16961500](https://pubmed.ncbi.nlm.nih.gov/16961500). [S2CID](/source/S2CID_(identifier)) [12485813](https://api.semanticscholar.org/CorpusID:12485813).

1. **[^](#cite_ref-10)** Vitvar; et al. (2002). ["Estimation of baseflow residence times in watersheds from the runoff hydrograph recession: method and application in the Neversink watershed, Catskill Mountains, New York"](https://web.archive.org/web/20160303185145/http://www.cof.orst.edu/cof/fe/watershd/pdf/2002/Vitvar_et_al_2002.pdf) (PDF). *Hydrol. Processes*. **16** (9): 1871–1877. [Bibcode](/source/Bibcode_(identifier)):[2002HyPr...16.1871V](https://ui.adsabs.harvard.edu/abs/2002HyPr...16.1871V). [doi](/source/Doi_(identifier)):[10.1002/hyp.5027](https://doi.org/10.1002%2Fhyp.5027). [S2CID](/source/S2CID_(identifier)) [28833693](https://api.semanticscholar.org/CorpusID:28833693). Archived from [the original](http://www.cof.orst.edu/cof/fe/watershd/pdf/2002/Vitvar_et_al_2002.pdf) (PDF) on 2016-03-03. Retrieved 2009-07-10.

1. ^ [***a***](#cite_ref-:0_11-0) [***b***](#cite_ref-:0_11-1) Price, Katie (2011). "Effects of watershed topography, soils, land use, and climate on baseflow hydrology in humid regions: A review". *Progress in Physical Geography*. **35** (4): 465–492. [Bibcode](/source/Bibcode_(identifier)):[2011PrPG...35..465P](https://ui.adsabs.harvard.edu/abs/2011PrPG...35..465P). [doi](/source/Doi_(identifier)):[10.1177/0309133311402714](https://doi.org/10.1177%2F0309133311402714). [S2CID](/source/S2CID_(identifier)) [7544941](https://api.semanticscholar.org/CorpusID:7544941).

v t e Rivers, streams and springs Rivers (lists) Alluvial river Braided river Blackwater river Channel Channel pattern Channel types Confluence Distributary Drainage basin Mountain river Subterranean river River bifurcation River ecosystem River source Tributary Streams Arroyo Beck Bourne Burn Chalk stream Coulee Current Stream bed Stream channel Streamflow Stream gradient Stream pool Perennial stream Winterbourne Springs (list) Estavelle/Inversac Geyser Holy well Hot spring list list in the US Karst spring list Mineral spring Ponor Rhythmic spring Spring horizon Sedimentary processes and erosion Abrasion Anabranch Aggradation Armor Bed load Bed material load Granular flow Debris flow Deposition Dissolved load Downcutting Erosion Headward erosion Knickpoint Palaeochannel Progradation Retrogradation Saltation Secondary flow Sediment transport Suspended load Wash load Water gap Fluvial landforms Ait Alluvial fan Antecedent drainage stream Avulsion Bank Bar Bayou Billabong Canyon Chine Cut bank Estuary Floating island Fluvial terrace Gill Gulch Gully Glen Meander scar Mouth bar Oxbow lake Riffle-pool sequence Point bar Ravine Rill River island Rock-cut basin Sedimentary basin Sedimentary structures Strath Thalweg River valley Wadi Fluvial flow Helicoidal flow International scale of river difficulty Log jam Meander Plunge pool Rapids Riffle Shoal Stream capture Waterfall list of waterfalls Whitewater Surface runoff Agricultural wastewater First flush Urban runoff Floods and stormwater 100-year flood Crevasse splay Flash flood Flood Urban flooding Non-water flood Flood barrier Flood control Flood forecasting Flood-meadow Floodplain Flood pulse concept Flooded grasslands and savannas Inundation Storm Water Management Model Return period Point source pollution Effluent Industrial wastewater Sewage River measurement and modelling Baer's law Baseflow Bradshaw model Discharge (hydrology) Drainage density Exner equation Groundwater model Hack's law Hjulström curve Hydrograph Hydrological model Hydrological transport model Infiltration (hydrology) Main stem Playfair's law Relief ratio River Continuum Concept Rouse number Runoff curve number Runoff model (reservoir) Stream gauge WAFLEX Wetted perimeter Volumetric flow rate River engineering Aqueduct Balancing lake Canal Check dam Dam Drop structure Daylighting Detention basin Erosion control Fish ladder Floodplain restoration Flume Infiltration basin Leat Levee River morphology Retention basin Revetment Riparian-zone restoration Stream restoration Weir River sports Canyoning Fly fishing Rafting River surfing Riverboarding Stone skipping Triathlon Whitewater canoeing Whitewater kayaking Whitewater slalom Related Aquifer Aquatic toxicology Body of water Hydraulic civilization Limnology Riparian zone River valley civilization River cruise Sacred waters Surface water Wild river Rivers by length Rivers by discharge rate Drainage basins Whitewater rivers Flash floods River name etymologies Countries without rivers

Authority control databases International GND Other Yale LUX

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Adapted from the Wikipedia article [Baseflow](https://en.wikipedia.org/wiki/Baseflow) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Baseflow?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.