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| Titel |
Modelling hyporheic processes for regulated rivers under transient hydrological and hydrogeological conditions |
| VerfasserIn |
D. Siergieiev, L. Ehlert, T. Reimann, A. Lundberg, R. Liedl |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 19, no. 1 ; Nr. 19, no. 1 (2015-01-16), S.329-340 |
| Datensatznummer |
250120595
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| Publikation (Nr.) |
 copernicus.org/hess-19-329-2015.pdf |
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| Zusammenfassung |
| Understanding the effects of major hydrogeological controls on hyporheic
exchange and bank storage is essential for river water management,
groundwater abstraction, restoration and ecosystem sustainability.
Analytical models cannot adequately represent complex settings with, for
example, transient boundary conditions, varying geometry of surface water–groundwater
interface, unsaturated and overland flow, etc. To
understand the influence of parameters such as (1) sloping river banks, (2)
varying hydraulic conductivity of the riverbed and (3) different river
discharge wave scenarios on hyporheic exchange characteristics such as (a)
bank storage, (b) return flows and (c) residence time, a 2-D hydrogeological
conceptual model and, subsequently, an adequate numerical model were
developed. The numerical model was calibrated against observations in the
aquifer adjacent to the hydropower-regulated Lule River, northern Sweden,
which has predominantly diurnal discharge fluctuations during summer and
long-lasting discharge peaks during autumn and winter. Modelling results
revealed that bank storage increased with river wave amplitude, wave
duration and smaller slope of the river bank, while maximum exchange flux
decreased with wave duration. When a homogeneous clogging layer covered the
entire river–aquifer interface, hydraulic conductivity positively affected
bank storage. The presence of a clogging layer with hydraulic conductivity
< 0.001 m d−1 significantly reduced the exchange flows and
virtually eliminated bank storage. The bank storage return/fill time ratio
was positively related to wave amplitude and the hydraulic conductivity of
the interface and negatively to wave duration and bank slope. Discharge
oscillations with short duration and small amplitude decreased bank storage
and, therefore, the hyporheic exchange, which has implications for solute
fluxes, redox conditions and the potential of riverbeds as fish-spawning
locations. Based on these results, river regulation strategies can be
improved by considering the effect of certain wave event configurations on
hyporheic exchange to ensure harmonious hydrogeochemical functioning of the
river–aquifer interfaces and related ecosystems. |
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