Baseflow: Difference between revisions

Revision as of 13:40, 15 January 2021

Revision as of 18:51, 15 February 2021

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== Importance ==

Baseflow is important for sustaining human [[Center of population|centers of population]] and [[ecosystem]]s.<ref name=":0">{{Cite journal|last=Price|first=Katie|date=2011|title=Effects of watershed topography, soils, land use, and climate on baseflow hydrology in humid regions: A review|journal=Progress in Physical Geography|volume=35|issue=4|pages=465–492|doi=10.1177/0309133311402714|s2cid=7544941}}</ref> This is especially true for [[Drainage basin|watersheds]] that do not rely on [[snowmelt]]. Different ecological processes will occur at different parts of the [[hydrograph]]. During the baseflow ascending limb there is frequently more [[stream]] area and [[habitat]] available for water dependent species, spawning [[salmon]] for example. During the recession limb which in California is from May to October there is increasingly less stream area, [[indigenous (ecology)|indigenous]] species are more adapt at surviving in low flow conditions than [[introduced species]].

== Geology ==

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== Measurement ==

Methods for identifying baseflow sources and residence/transit time include using [[Solution|solutes]] and [[Flow tracer|tracer]]s. 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.<ref>{{Cite journal|lastlast1=Glynn|firstfirst1=Pierre D.|last2=Plummer|first2=L. Niel|date=2005-03-01|title=Geochemistry and the understanding of ground-water systems|journal=Hydrogeology Journal|language=en|volume=13|issue=1|pages=263–287|doi=10.1007/s10040-004-0429-y|bibcode=2005HydJ...13..263G|s2cid=129716764|issn=1431-2174}}</ref>

Methods for summarizing baseflow from an existing streamflow record include event based low flow statistics,<ref>{{Cite journal|last=O'Keeffe|first=Jay|date=2009|title=Sustaining river ecosystems: balancing use and protection|journal=Progress in Physical Geography: Earth and Environment|volume=33|issue=3|pages=339–357|doi=10.1177/0309133309342645|s2cid=131587514}}</ref> flow duration curve,<ref>{{Cite book|title=Handbook of Hydrology|last=Stedinger, JR, Vogel, RM, and Foufoula-Georgiou, E|publisher=McGraw-Hill|year=1993}}</ref> metrics that explain proportioning of baseflow to total flow,<ref>{{Cite journal|date=2009-06-30|title=Examining geological controls on baseflow index (BFI) using regression analysis: An illustration from the Thames Basin, UK|journal=Journal of Hydrology|language=en|volume=373|issue=1–2|pages=164–176|doi=10.1016/j.jhydrol.2009.04.025|issn=0022-1694|last1=Bloomfield|first1=J.P.|last2=Allen|first2=D.J.|last3=Griffiths|first3=K.J.|bibcode=2009JHyd..373..164B|url=http://nora.nerc.ac.uk/id/eprint/7510/1/Bloomfield%20Allen%20Griffiths%202009.pdf}}</ref> and the baseflow recession curve which can be used on ungauged streams based on empirical relationship between watershed characteristics and baseflow at gauged sites.<ref>{{Cite journal|lastlast1=Posavec|firstfirst1=Kristijan|last2=Bacani|first2=Andrea|last3=Nakic|first3=Zoran|date=2006-05-26|title=A Visual Basic Spreadsheet Macro for Recession Curve Analysis|journal=Ground Water|language=en|volume=0|issue=5|pages=060526082055001––|doi=10.1111/j.1745-6584.2006.00226.x|pmid=16961500|issn=0017-467X}}</ref>

Certain parameters of baseflow, such as the [[Mean baseflow residence time|mean 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.<ref>{{cite journal|author=Vitvar|display-authors=etal|year=2002|title=Estimation of baseflow residence times in watersheds from the runoff hydrograph recession: method and application in the Neversink watershed, Catskill Mountains, New York|url=http://www.cof.orst.edu/cof/fe/watershd/pdf/2002/Vitvar_et_al_2002.pdf|journal=Hydrol. Processes|volume=16|issue=9|pages=1871–1877|doi=10.1002/hyp.5027|bibcode=2002HyPr...16.1871V}}</ref>

Baseflow separation is often used to determine what portion of a streamflow [[hydrograph]] occurs from baseflow, and what portion occurs from [[overland flow]]. Common methods include using [[Isotope hydrology|isotope tracing]] and the software program [https://water.usgs.gov/software/HYSEP/ HYSEP], among others.