Threshold changes in storm runoff generation at a till-mantled headwater catchment

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dc.contributor.authorDetty, J. M.en
dc.contributor.authorMcGuire, Kevin J.en
dc.contributor.departmentForest Resources and Environmental Conservationen
dc.contributor.departmentVirginia Water Resources Research Centeren
dc.date.accessioned2017-01-12T01:35:00Zen
dc.date.available2017-01-12T01:35:00Zen
dc.date.issued2010-07-20en
dc.description.abstractA small research watershed in the Hubbard Brook Experimental Forest in New Hampshire was equipped with a spatially distributed instrument network designed to continuously monitor hydrometric responses in the shallow subsurface. We analyzed rainfall events during seasonal wet up from late summer through autumn to investigate the mechanisms of runoff generation and the patterns of rainfall!runoff response at the catchment outlet. Our results show that storm quick flow depths displayed a threshold relationship with two independently measured soil moisture indices: a maximum water table height index and the sum of gross precipitation and antecedent soil moisture. Quick flow depths during events with below!threshold criteria were not significantly correlated with either index, while quick flow depths during events with above!threshold criteria were strongly correlated with both indices (r ! 0.98). The effective runoff contributing area (estimated by event runoff ratios) also changed significantly between above! and below!threshold conditions, as did the synchronicity between groundwater fluctuations and streamflow. Below the threshold, we inferred that catchment runoff was generated primarily in the near!stream zones, while above the threshold the contributing area likely expanded laterally onto neighboring hillslopes. Our results show that the effective saturated hydraulic conductivity appeared to increase significantly during runoff events with above!threshold conditions, possibly owing to water tables rising into highly transmissive near!surface soils. We believe the observed threshold pattern may partially be explained as a transmissivity feedback mechanism and/or preferential flows through macropore networks which allowed for a rapid expansion of the runoff contributing area onto hillslopes, resulting in increased runoff yields. continuously monitor hydrometric responses in the shallow subsurface. We analyzed rainfall events during seasonal wet up from late summer through autumn to investigate the mechanisms of runoff generation and the patterns of rainfall!runoff response at the catchment outlet. Our results show that storm quick flow depths displayed a threshold relationship with two independently measured soil moisture indices: a maximum water table height index and the sum of gross precipitation and antecedent soil moisture. Quick flow depths during events with below!threshold criteria were not significantly correlated with either index, while quick flow depths during events with above!threshold criteria were strongly correlated with both indices (r ! 0.98). The effective runoff contributing area (estimated by event runoff ratios) also changed significantly between above! and below!threshold conditions, as did the synchronicity between groundwater fluctuations and streamflow. Below the threshold, we inferred that catchment runoff was generated primarily in the near!stream zones, while above the threshold the contributing area likely expanded laterally onto neighboring hillslopes. Our results show that the effective saturated hydraulic conductivity appeared to increase significantly during runoff events with above!threshold conditions, possibly owing to water tables rising into highly transmissive near!surface soils. We believe the observed threshold pattern may partially be explained as a transmissivity feedback mechanism and/or preferential flows through macropore networks which allowed for a rapid expansion of the runoff contributing area onto hillslopes, resulting in increased runoff yields.en
dc.description.versionPublished versionen
dc.format.extent? - ? (15) page(s)en
dc.identifier.doihttps://doi.org/10.1029/2009WR008102en
dc.identifier.issn0043-1397en
dc.identifier.orcidMcGuire, Kevin J. [0000-0001-5751-3956]en
dc.identifier.urihttp://hdl.handle.net/10919/74265en
dc.identifier.volume46en
dc.languageEnglishen
dc.publisherAmerican Geophysical Unionen
dc.relation.urihttp://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000280339700001&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=930d57c9ac61a043676db62af60056c1en
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectEnvironmental Sciencesen
dc.subjectLimnologyen
dc.subjectWater Resourcesen
dc.subjectEnvironmental Sciences & Ecologyen
dc.subjectMarine & Freshwater Biologyen
dc.subjectNORTHERN HARDWOOD FORESTen
dc.subjectOLD WATERen
dc.subjectSTREAMFLOW GENERATIONen
dc.subjectHILLSLOPE SCALEen
dc.subjectDOUBLE PARADOXen
dc.subjectLATERAL FLOWen
dc.subjectNEW-ZEALANDen
dc.subjectSOILen
dc.subjectECOSYSTEMen
dc.subjectMODELen
dc.titleThreshold changes in storm runoff generation at a till-mantled headwater catchmenten
dc.title.serialWater Resources Researchen
dc.typeArticle - Refereeden
pubs.organisational-group/Virginia Techen
pubs.organisational-group/Virginia Tech/All T&R Facultyen
pubs.organisational-group/Virginia Tech/Natural Resources & Environmenten
pubs.organisational-group/Virginia Tech/Natural Resources & Environment/CNRE T&R Facultyen
pubs.organisational-group/Virginia Tech/Natural Resources & Environment/Water Resources Research Centeren

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