Spatial aggregation of time-variant stream water ages in urbanizing catchments

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Abstract

We calibrated an integrated flow–tracer model to simulate spatially distributed isotope time series in stream water in a 7.9-km2 catchment with an urban area of 13%. The model used flux tracking to estimate the time-varying age of stream water at the outlet and both urbanized (1.7 km2) and non-urban (4.5 km2) sub-catchments over a 2.5-year period. This included extended wet and dry spells where precipitation equated to >10-year return periods. Modelling indicated that stream water draining the most urbanized tributary was youngest with a mean transit time (MTT) of 171 days compared with 456 days in the non-urban tributary. For the larger catchment, the MTT was 280 days. Here, the response of urban contributing areas dominated smaller and more moderate runoff events, but rural contributions dominated during the wettest periods, giving a bi-modal distribution of water ages. Whilst the approach needs refining for sub-daily time steps, it provides a basis for projecting the effects of urbanization on stream water transit times and their spatial aggregation. This offers a novel approach for understanding the cumulative impacts of urbanization on stream water quantity and quality, which can contribute to more sustainable management.
Original languageEnglish
Pages (from-to)3038-3050
Number of pages13
JournalHydrological Processes
Volume29
Issue number13
Early online date22 May 2015
DOIs
Publication statusPublished - 30 Jun 2015

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catchment
water
tributary
urbanization
urban area
return period
isotope
time series
runoff
modeling

Keywords

  • isotopes
  • transit times
  • conceptual models
  • non-stationarity
  • urban hydrology

Cite this

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title = "Spatial aggregation of time-variant stream water ages in urbanizing catchments",
abstract = "We calibrated an integrated flow–tracer model to simulate spatially distributed isotope time series in stream water in a 7.9-km2 catchment with an urban area of 13{\%}. The model used flux tracking to estimate the time-varying age of stream water at the outlet and both urbanized (1.7 km2) and non-urban (4.5 km2) sub-catchments over a 2.5-year period. This included extended wet and dry spells where precipitation equated to >10-year return periods. Modelling indicated that stream water draining the most urbanized tributary was youngest with a mean transit time (MTT) of 171 days compared with 456 days in the non-urban tributary. For the larger catchment, the MTT was 280 days. Here, the response of urban contributing areas dominated smaller and more moderate runoff events, but rural contributions dominated during the wettest periods, giving a bi-modal distribution of water ages. Whilst the approach needs refining for sub-daily time steps, it provides a basis for projecting the effects of urbanization on stream water transit times and their spatial aggregation. This offers a novel approach for understanding the cumulative impacts of urbanization on stream water quantity and quality, which can contribute to more sustainable management.",
keywords = "isotopes, transit times, conceptual models, non-stationarity, urban hydrology",
author = "Christopher Soulsby and Christian Birkel and Josie Geris and Doerthe Tetzlaff",
note = "Date of Acceptance: 25/03/2015 Acknowledgements The help of Clara F. Soulsby with the sampling is gratefully acknowledged.",
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T1 - Spatial aggregation of time-variant stream water ages in urbanizing catchments

AU - Soulsby, Christopher

AU - Birkel, Christian

AU - Geris, Josie

AU - Tetzlaff, Doerthe

N1 - Date of Acceptance: 25/03/2015 Acknowledgements The help of Clara F. Soulsby with the sampling is gratefully acknowledged.

PY - 2015/6/30

Y1 - 2015/6/30

N2 - We calibrated an integrated flow–tracer model to simulate spatially distributed isotope time series in stream water in a 7.9-km2 catchment with an urban area of 13%. The model used flux tracking to estimate the time-varying age of stream water at the outlet and both urbanized (1.7 km2) and non-urban (4.5 km2) sub-catchments over a 2.5-year period. This included extended wet and dry spells where precipitation equated to >10-year return periods. Modelling indicated that stream water draining the most urbanized tributary was youngest with a mean transit time (MTT) of 171 days compared with 456 days in the non-urban tributary. For the larger catchment, the MTT was 280 days. Here, the response of urban contributing areas dominated smaller and more moderate runoff events, but rural contributions dominated during the wettest periods, giving a bi-modal distribution of water ages. Whilst the approach needs refining for sub-daily time steps, it provides a basis for projecting the effects of urbanization on stream water transit times and their spatial aggregation. This offers a novel approach for understanding the cumulative impacts of urbanization on stream water quantity and quality, which can contribute to more sustainable management.

AB - We calibrated an integrated flow–tracer model to simulate spatially distributed isotope time series in stream water in a 7.9-km2 catchment with an urban area of 13%. The model used flux tracking to estimate the time-varying age of stream water at the outlet and both urbanized (1.7 km2) and non-urban (4.5 km2) sub-catchments over a 2.5-year period. This included extended wet and dry spells where precipitation equated to >10-year return periods. Modelling indicated that stream water draining the most urbanized tributary was youngest with a mean transit time (MTT) of 171 days compared with 456 days in the non-urban tributary. For the larger catchment, the MTT was 280 days. Here, the response of urban contributing areas dominated smaller and more moderate runoff events, but rural contributions dominated during the wettest periods, giving a bi-modal distribution of water ages. Whilst the approach needs refining for sub-daily time steps, it provides a basis for projecting the effects of urbanization on stream water transit times and their spatial aggregation. This offers a novel approach for understanding the cumulative impacts of urbanization on stream water quantity and quality, which can contribute to more sustainable management.

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KW - transit times

KW - conceptual models

KW - non-stationarity

KW - urban hydrology

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SN - 0885-6087

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ER -