Influence of lowland aquifers and anthropogenic impacts on the isotope hydrology of contrasting mesoscale catchments

Scott James McGrane, Doerthe Tetzlaff, Chris Soulsby

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

We examined the isotope hydrology of eight, contrasting mesoscale (104–488 km2) catchments characterized by a systematic change in the relative importance of upland and lowland areas that reflects the relative distribution of metamorphic and sedimentary rocks. Precipitation and stream water were monitored over a 12-month period, and stable isotopes were used to examine spatial variations in the hydrometric and tracer dynamics of the catchments. Isotopic tracers were used to examine the temporal dynamics of different runoff sources, and geochemical tracers (alkalinity) were used to identify the geographic sources of runoff. Input–output relationships of isotopic tracers were explored using a gamma function to fit a transit time distribution, which was used to test the hypothesis that the length of mean transit times increased systematically with the cover of sandstone aquifers in the catchments. However, in three catchments, the increased influence of anthropogenic factors, notably reservoir storage, urban runoff and agricultural abstraction for irrigation, prevented reliable transit time estimation. For sites where tentative mean transit time estimates were possible, these varied from around 1.6 years in upland catchments dominated by metamorphic rocks (>75%) and responsive soils to around 4 years in catchments with 34% sandstone cover and freely draining soils. These preliminary results were consistent with inferences of geochemical tracers on the increased role of sedimentary aquifers as runoff sources in lowland areas, but observation from a larger number of sites is needed to confirm this.
LanguageEnglish
Pages793-808
Number of pages16
JournalHydrological Processes
Volume28
Issue number3
Early online date21 Nov 2012
DOIs
Publication statusPublished - 30 Jan 2014

Fingerprint

hydrology
aquifer
isotope
catchment
tracer
runoff
metamorphic rock
sandstone
alkalinity
sedimentary rock
stable isotope
spatial variation
soil
irrigation
water
distribution

Keywords

  • tracers
  • stable isotopes
  • transit times
  • Lowlands

Cite this

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abstract = "We examined the isotope hydrology of eight, contrasting mesoscale (104–488 km2) catchments characterized by a systematic change in the relative importance of upland and lowland areas that reflects the relative distribution of metamorphic and sedimentary rocks. Precipitation and stream water were monitored over a 12-month period, and stable isotopes were used to examine spatial variations in the hydrometric and tracer dynamics of the catchments. Isotopic tracers were used to examine the temporal dynamics of different runoff sources, and geochemical tracers (alkalinity) were used to identify the geographic sources of runoff. Input–output relationships of isotopic tracers were explored using a gamma function to fit a transit time distribution, which was used to test the hypothesis that the length of mean transit times increased systematically with the cover of sandstone aquifers in the catchments. However, in three catchments, the increased influence of anthropogenic factors, notably reservoir storage, urban runoff and agricultural abstraction for irrigation, prevented reliable transit time estimation. For sites where tentative mean transit time estimates were possible, these varied from around 1.6 years in upland catchments dominated by metamorphic rocks (>75{\%}) and responsive soils to around 4 years in catchments with 34{\%} sandstone cover and freely draining soils. These preliminary results were consistent with inferences of geochemical tracers on the increased role of sedimentary aquifers as runoff sources in lowland areas, but observation from a larger number of sites is needed to confirm this.",
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Influence of lowland aquifers and anthropogenic impacts on the isotope hydrology of contrasting mesoscale catchments. / McGrane, Scott James; Tetzlaff, Doerthe; Soulsby, Chris.

In: Hydrological Processes, Vol. 28, No. 3, 30.01.2014, p. 793-808.

Research output: Contribution to journalArticle

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