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| Titel |
Impacts of Extreme Flood Inundation on Bank Filtration Water Quality |
| VerfasserIn |
Matthew Ascott, Daniel Lapworth, Daren Gooddy, Robert Sage, Ilias Karapanos, Robert Ward |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250102227
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| Publikation (Nr.) |
 EGU/EGU2015-1534.pdf |
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| Zusammenfassung |
| Bank filtration systems are a significant component of global water supply and considered to
be vulnerable to climate change. Understanding the resilience and water quality recovery of
these systems following severe flooding is critical for effective water resources
planning and management under potential future climate change. We provide the first
systematic assessment of the recovery in water quality following extreme inundation at a
bank filtration site following an extreme (1 in 17 year, duration > 70 days) flood
event. During the inundation event, bank filtrate water quality is dominated by rapid
direct recharge and floodwater infiltration (fraction of surface water, fSW ≈ 1,
high DOC > 140% steady state values (SS), > 1 log increase in micro-organic
contaminants, microbial detects and turbidity, low SEC < 90% SS, low nitrate,
high DO > 500% SS). A rapid recovery is observed in water quality with most
floodwater impacts only observed for 2 - 3 weeks after the flooding event and a
return to normal groundwater conditions within 6 weeks (fSW ≈ 0.2 – 0.5, higher
nitrate and SEC, lower DOC, organic and microbial detects, DO). Recovery rates are
constrained by the hydrogeological setting of the site, the abstraction regime and the
water quality trends at site boundary conditions. In this case, increased abstraction
rates and a high transmissivity aquifer facilitate rapid water quality recoveries,
with longer term trends controlled by background river and groundwater qualities.
Temporary reductions in abstraction rates appear to slow water quality recoveries.
Water resources planners and managers should consider flexible operating regimes
such as the one implemented at this study site if riverbank filtration systems are to
be resilient to future inundation events under climate change. Development of a
conceptual understanding of hydrochemical boundaries and site hydrogeology through
monitoring is required to assess the suitability of a prospective bank filtration site
against a background of climate change and uncertainty in water resource security. |
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